WO2021174742A1 - 一种动物的制备方法 - Google Patents

一种动物的制备方法 Download PDF

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WO2021174742A1
WO2021174742A1 PCT/CN2020/101681 CN2020101681W WO2021174742A1 WO 2021174742 A1 WO2021174742 A1 WO 2021174742A1 CN 2020101681 W CN2020101681 W CN 2020101681W WO 2021174742 A1 WO2021174742 A1 WO 2021174742A1
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animal
sequence
cell
mice
human
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French (fr)
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吴光明
陈捷凯
吴凯昕
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Bioisland Laboratory
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Bioisland Laboratory
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Priority to JP2022553625A priority patent/JP7578306B2/ja
Priority to US17/909,294 priority patent/US20240263194A1/en
Publication of WO2021174742A1 publication Critical patent/WO2021174742A1/zh
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Definitions

  • the present disclosure belongs to the field of biomedicine, and relates to a preparation method of animals.
  • mice mice, rats, guinea pigs, hamsters (hamsters), rabbits, dogs, monkeys, pigs and fish.
  • hamsters hamsters
  • rabbits dogs, monkeys, pigs and fish.
  • human and animal genes and protein sequences Many human proteins cannot be combined with animal homologous proteins to produce biological activity. As a result, the results of many clinical trials are also inconsistent with the results of animal experiments.
  • human cells or genes are used to replace or replace the endogenous cells or genes of animals in order to establish biological systems or disease models closer to humans, and to establish humanized experimental animal models (humanized experimental animal models). animal model), which has provided an important tool for new clinical treatment methods or means.
  • the gene humanized animal model is the use of genetic genetic manipulation technology to replace the human normal or mutant gene with the same animal gene, and the normal or mutant that is closer to the human can be established in the animal. Due to the presence of human gene fragments, animals can express or partially express proteins containing human functions, which greatly reduces the difference in clinical trials between humans and animals, and provides the possibility for drug screening at the animal level.
  • 2019-nCoV uses Angiotensin-converting enzyme 2 (ACE2) as a key target for human infection.
  • ACE2 Angiotensin-converting enzyme 2
  • 2019-nCoV can also infect a variety of mammals such as monkeys. , Pigs, rabbits, ferrets, orangutans, etc., except for mice and rats.
  • Monkeys, pigs, and rabbits are used as animal models to infect 2019-nCoV for drug screening. They have a long growth cycle and large body size, which is difficult to operate in large quantities, while mouse models that are relatively easy to operate in large quantities are not easy to operate on 2019-nCoV. feel.
  • Tetraploid refers to the number of chromosomes contained in a cell that is four times the minimum number of chromosomes, that is, a biological individual or cell with four complete chromosomes in the cell. Under natural conditions, the incidence of mammalian tetraploid embryos is extremely low and generally cannot develop into a single individual normally.
  • ES cells and tetraploid embryos are chimerized.
  • ES cells and tetraploid embryos are not randomly distributed, that is, the tetraploid embryo part only participates in the yolk sac.
  • extra-embryonic tissues such as endoderm and placental trophoblast cells (such as chorionic ectoderm, trophoblast cells, etc.)
  • ES cells are widely involved in embryonic body, allantoic, amniotic membrane, yolk sac mesoderm and chorionic mesoderm Part of the production, without participating in the production of yolk sac endoderm and placental trophoblast cell lineages, that is, the developmental potential of the two are complementary. This phenomenon is called tetraploid complementation technology.
  • the individual animals cloned by this technology are entirely derived from ES cells, and we call them ES animals.
  • the birth rate of the fetus after the cloned embryos prepared by the nuclear transfer method is transferred to the surrogate mother is extremely low, only 1-2%, and through the tetraploid compensation technology, the ESC cell line is injected into the blastocyst stage tetraploid embryo carrier , Can increase the birth rate of the fetus to 20-30%, significantly improving the efficiency of animal cloning.
  • many scientists at home and abroad have studied this technology in depth and have achieved many creative research results.
  • the animal models generated by the tetraploid compensation technology have very common applications, such as determining lineage-specific gene functions, analyzing gene functions of extraembryonic and embryonic tissues, identifying spontaneous and non-spontaneous gene functions of cells, and distinguishing between primary and secondary Defects, promote phenotypic analysis, etc.
  • the application of embryonic chimerism is not limited to the study of early embryonic development, but can also be applied to the study of fetal development and body function after birth.
  • chimeras are used in combination with molecular tools, such molecular tools can modify genetic activity in cells in a time- and lineage-specific manner, facilitating precise, in-depth, and large-scale analysis of gene functions.
  • ES cells mainly focuses on the study of cell differentiation in vitro and the analysis of transcriptional activity of molecular markers reflecting the pluripotency of cells.
  • a unique feature of embryonic chimerism is that foreign cells can be chimerized into the embryo, and the cells can fully stimulate their differentiation potential during embryonic development. Cells are tested on a comprehensive cell lineage, which can reveal the true degree of pluripotency. Chimera is the most comprehensive and rigorous tool for in vivo evaluation of mammalian pluripotency cells.
  • the present disclosure provides a preparation method that can increase the birth rate of animals.
  • the present disclosure provides an animal tetraploid compensation or complementation method (tetraploid embryo complementation).
  • the present disclosure provides a method for preparing an animal, the method comprising polymerizing a tetraploid embryo with embryonic stem cells to form a new reconstructed embryo or chimeric embryo; the tetraploid embryo is in Tetraploid embryos at the 2-cell stage.
  • the embryonic stem cells are embryonic stem cells whose passage number is within p15.
  • the embryonic stem cells are embryonic stem cells with generation number p12-p15.
  • the method uses a tetraploid compensation method or a tetraploid embryo complementation method (tetraploid embryo complementation).
  • the method includes the following steps: (1) Obtaining animal 2-cell embryos; (2) Putting the 2-cell embryos described in step (1) into a fusion solution for fusion to obtain a tetraploid Embryos; (3) Put the tetraploid embryos in step (2) into culture medium; (4) Aggregate the tetraploid embryos that developed to the 2-cell stage in step (3) with embryonic stem cells to form a mosaic Zygote embryo; (5) implant the chimera embryo in step (4) into the uterus of a pseudopregnant animal, and the embryo develops to full pregnancy, thereby obtaining an animal.
  • the culture time in step (3) is 8-24 hours.
  • the medium in step (3) is KSOM medium.
  • the non-human animal derived from the recipient embryo can be any animal other than humans, such as pigs, rats, mice, hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens , Cats, horses, dogs, orangutans, monkeys.
  • the mammal used as the original source of the cells transplanted into the recipient may be a human or a mammal other than humans, such as strains, rats, mice, cattle, sheep, goats, horses, dogs, and baboons. , Chimpanzees, gorillas, orangutans, monkeys, marmosets, and bonobos.
  • the animal is a mammal.
  • the animal is a non-human mammal.
  • the animal is selected from pigs, rats, mice, hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens, cats, horses, dogs, orangutans, and monkeys.
  • the animal is selected from mice. In some embodiments, the animal is selected from adult mice. In some embodiments, the animal is selected from fetal mice.
  • mice early studies found that mouse tetraploid embryos cannot develop normally and can only form placental trophoblasts and extraembryonic endoderm (Tarkowski et al., 1977), while embryonic stem cells can form entire fetuses. It itself, as well as the mesoderm of the yolk sac, amniotic membrane, allantoic, umbilical cord, etc., but the formation of trophoblast and yolk sac endoderm is very limited (Beddington et al., 1989). The tetraploid compensation technology is based on this perfect complementary relationship. In the most extreme case, using the best quality embryonic stem cells with pure genetic background, the fetal birth rate can reach up to 15%, but these mice All died soon after birth (Nagy et al., 1990).
  • mice birth rate of mice is 0-7%, mostly 0% (Boland et al., 2009), among which Zhou Qi is in The birth rate published in the international journal NATURE is only between 0-3% (Zhao et al., 2009).
  • the present disclosure provides a method of preparing a gene-edited animal, using the method of preparing the animal.
  • the animal is a genetically humanized animal.
  • the animal is a mammal.
  • the animal is a non-human mammal.
  • the animal is selected from pigs, rats, mice, hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens, cats, horses, dogs, orangutans, and monkeys.
  • the rodent is a mouse.
  • the animal is an adult mouse.
  • the animal is a fetal mouse.
  • Gene-edited mice are usually obtained in the following ways: blastocyst injection of pluripotent stem cells; direct editing of fertilized egg injection; somatic cell nuclear transfer; tetraploid compensation technology, etc.
  • the injection of pluripotent stem cell blastocysts requires germline transmission of chimeric mice and then intergenerational reproduction to obtain homozygous mice. It takes more than 5 months; fertilized egg injection is generally used for gene knockout editing, and gene editing strategies are subject to It is limited and technically difficult to operate.
  • the subsequent identification of born mice may not directly obtain the target mouse; somatic cell nuclear transfer and tetraploid compensation technology can directly obtain homozygous gene-edited mice, but the two methods survive The rate is very low, below 10%, generally around 1%.
  • somatic cell nucleus transfer is difficult, and the microinjection causes greater damage to the embryo, and the tetraploid compensation method does not cause direct damage to the embryo.
  • the tetraploid compensation technology is simpler and more efficient than somatic cell nuclear transfer. It takes a short time to obtain gene-edited animals, and it is relatively easy to perform gene editing on pluripotent stem cells.
  • a method for preparing genetic mice includes the following steps: (1) obtaining mouse 2-cell embryos; (2) placing the 2-cell embryos described in step (1) Into the fusion solution, fusion is performed to obtain tetraploid embryos; (3) Put the tetraploid embryos in step (2) into culture medium; (4) develop to the 2-cell stage in step (3) The tetraploid embryo and embryonic stem cells aggregate to form a chimeric embryo; (5) The chimeric embryo in step (4) is implanted into the uterus of a pseudopregnant mouse, and the embryo develops to full pregnancy, thereby obtaining a gene-edited mouse .
  • the method includes polymerizing embryonic stem cells and tetraploid embryos to form new reconstructed embryos.
  • the embryonic stem cells can be ordinary embryonic stem cells, or gene-edited embryonic stem cells, such as humanized gene animal embryonic stem cells, etc., and the details are not limited.
  • a method for preparing animal chimeric embryos comprising polymerizing tetraploid embryos with embryonic stem cells to form new reconstructed embryos or chimeric embryos; the tetraploid embryos are in Tetraploid embryos at the 2-cell stage.
  • the method uses a tetraploid compensation method or a tetraploid embryo complementation method.
  • the method includes the following steps: (1) Obtaining animal 2-cell embryos; (2) Putting the 2-cell embryos described in step (1) into a fusion solution for fusion to obtain a tetraploid Embryos; (3) Put the tetraploid embryos in step (2) into culture medium; (4) Aggregate the tetraploid embryos that developed to the 2-cell stage in step (3) with embryonic stem cells to form a mosaic Zygote embryo.
  • the culture time in step (3) is 8-24 hours.
  • the medium in step (3) is KSOM medium.
  • the animal is a mammal. In some embodiments, the animal is a non-human mammal.
  • the animal is selected from pigs, rats, mice, hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens, cats, horses, dogs, orangutans, and monkeys. In some embodiments, the animal is selected from mice. In some embodiments, the animal is selected from adult mice. In some embodiments, the animal is selected from fetal mice.
  • the method includes polymerizing a tetraploid embryo that has developed to the 2-cell stage with embryonic stem cells to obtain a chimeric embryo.
  • the inventor also unexpectedly discovered that the use of 2-cell stage tetraploid embryos and embryonic stem cells to polymerize greatly improved the efficiency and stability of tetraploid compensation technology for making mice, and the efficiency of embryonic stem cells from pure-line mice Due to the low problem, the birth rate of mice has been qualitatively improved, which is close to normal embryo transfer. At the same time, it overcomes the limitations of the current most advanced gene editing method Cas9.
  • mice can be directly produced from stem cells for phenotypic research, saving mice
  • the large amount of time, manpower and material resources required for reproduction completely solved the practical problem of the tetraploid compensation technology used to make transgenic mice and reached the level of commercialization.
  • a composition in the method of preparing animals, a composition is used, and the ingredients include mannitol, MgSO 4 , CaCl 2 and bovine serum albumin; the mass ratio of mannitol, MgSO 4 , CaCl 2 and bovine serum albumin It is 9 to 53: 0.015 to 0.241: 0.013 to 0.23: 0.01 to 5.
  • the method uses a composition including mannitol, MgSO 4 , CaCl 2 and bovine serum albumin; the quality of the mannitol, MgSO 4 , CaCl 2 and bovine serum albumin The ratio is 9 to 53: 0.015 to 0.241: 0.013 to 0.23: 0.01 to 5.
  • the mass ratio of mannitol, MgSO 4 , CaCl 2 and bovine serum albumin in the composition is 18-52:0.018-0.241:0.016-0.23:0.01-4.
  • the mass ratio of mannitol, MgSO 4 , CaCl 2 and bovine serum albumin in the composition is 27-52:0.018-0.12:0.016-0.1:1-3.5.
  • the composition includes the following ingredients: mannitol 0.05-0.29M, MgSO 4 0.12-2 mM, CaCl 2 0.12-2 mM, and bovine serum albumin 0.01-5 mg/mL.
  • the composition includes the following ingredients: mannitol 0.1-0.28M, MgSO 4 0.15-2 mM, CaCl 2 0.15-2 mM, and bovine serum albumin 0.01-4 mg/mL.
  • the composition includes the following ingredients: mannitol 0.15-0.28M, MgSO 4 0.15-1 mM, CaCl 2 0.15-1 mM, and bovine serum albumin 1-3.5 mg/mL.
  • the composition includes the following ingredients: mannitol 0.18-0.28M, MgSO 4 0.15-0.5 mM, CaCl 2 0.15-0.5 mM, and bovine serum albumin 2-3.5 mg/mL.
  • the composition includes the following ingredients: mannitol 0.2-0.28M, MgSO 4 0.15-0.3 mM, CaCl 2 0.15-0.3 mM, and bovine serum albumin 2-3 mg/mL.
  • the composition includes the following ingredients: mannitol 0.27M, MgSO 4 0.2 mM, CaCl 2 0.2 mM, and bovine serum albumin 3 mg/mL.
  • the composition can be used as a mother liquor and then formulated into a working solution of the desired concentration.
  • the composition can be a working fluid, and can be used directly without preparation.
  • the present disclosure provides the application of the composition in the preparation of gene-edited animal embryo cells or gene-edited animals.
  • the composition is used to prepare animal tetraploid embryos.
  • the method uses a fusion fluid containing mannitol, bovine serum albumin, Mg 2+ and Ca 2+ , and the fusion fluid has an increased concentration of Mg 2+ and Ca 2+ ; or, the Mg 2+ and Ca 2+ concentrations of the fusion solution are 0.12-2 mM and 0.12-2 mM, respectively.
  • the concentrations of mannitol and bovine serum albumin in the fusion liquid are 0.05-0.29M and 0.01-5 mg/mL, respectively.
  • the Mg 2+ and Ca 2+ are derived from MgSO 4 and CaCl 2, respectively .
  • the fusion solution is used to prepare tetraploid embryos.
  • the methods for obtaining tetraploid include biological method, chemical method and physical method. Injecting two diploid embryonic nuclei into the cytoplasm of a 1-cell stage embryo by micromanipulation requires high technical requirements, and at the same time, micromanipulation is more harmful to the embryo; use cytochalasin B or colchicine to inhibit The division of blastomere cells to prepare tetraploid will have adverse effects on embryonic development, and even delay embryonic development; in addition, Sendai virus, polyethylene glycol, direct current shock and other methods can be used for cell fusion.
  • Sendai virus is pathogenic Polyethylene glycol residual toxicity, while the electrofusion method only produces reversible electroporation in a short time, which overcomes the toxicity of chemical reagents and the pathogenicity of viruses. It is the most commonly used and most efficient method for making tetraploid embryos. method. However, the existing tetraploid compensation technology still has the problem that the embryo electrofusion efficiency cannot reach 100%, the efficiency and stability of making mice are poor, and the efficiency of embryonic stem cells derived from pure mice is low. In the process of research, the inventor unexpectedly discovered that the fusion efficiency of the improved electrofusion fluid of the present disclosure can be increased from 80-90% to 100%, which has great practical significance.
  • the present disclosure provides animals prepared by the described methods.
  • the animal is a mammal. In some embodiments, the animal is a non-human mammal. In some embodiments, the animal is selected from pigs, rats, mice, hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens, cats, horses, dogs, orangutans, and monkeys. In some embodiments, the animal is selected from mice. In some embodiments, the animal is selected from adult mice. In some embodiments, the animal is selected from fetal mice. In some embodiments, the animal is selected from gene-edited animals. In some embodiments, the animal is selected from genetically humanized animals. In some embodiments, the gene is ACE2.
  • the present disclosure provides a fusion solution containing mannitol, bovine serum albumin, Mg 2+ and Ca 2+ , the fusion solution having an increased concentration of Mg 2+ and Ca 2+ ; or, The concentrations of Mg 2+ and Ca 2+ in the fusion solution are 0.12-2 mM and 0.12-2 mM, respectively.
  • the concentrations of mannitol and bovine serum albumin in the fusion liquid are 0.05-0.29M and 0.01-5 mg/mL, respectively.
  • the Mg 2+ and Ca 2+ are derived from MgSO 4 and CaCl 2, respectively .
  • the method of preparing an animal uses the fusion fluid.
  • the present disclosure provides a tissue, body fluid, cell, nucleus, and their fragments or extracts of a gene-edited animal or its descendants, and the animal is constructed using the above method.
  • the animal is a mammal.
  • the animal is a non-human mammal.
  • the animal is selected from pigs, rats, mice, hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens, cats, horses, dogs, orangutans, and monkeys.
  • the animal is selected from mice.
  • the animal is selected from adult mice.
  • the animal is selected from fetal mice.
  • human ACE2 and murine ACE2 have certain differences in gene sequence, it is reported in the literature that after virus infection, human ACE2 is more sensitive to SARS-CoV than murine ACE2, and the pathological symptoms are more obvious. The current clinical research urgently needs better animal models.
  • hACE2 transgenic mice can be infected with 2019-nCoV and show typical pathogenic characteristics of lung tissue (https://www.biorxiv.org/content/10.1101/2020.02.07.939389v3#disqus_thread).
  • the hACE2 transgenic mouse is a mouse model that overexpresses hACE2 systemically, and it cannot simulate the spatiotemporal tissue expression characteristics of ACE2.
  • the present disclosure will prepare 2019-nCoV-susceptible mouse humanized ACE2 animal models in large quantities by expressing humanized ACE2 at the mouse ACE2 site to conduct drug screening and disease research on 2019-nCoV And other applications.
  • the present disclosure provides a specific RNA fragment sequence.
  • the RNA fragment sequence is an isolated RNA fragment sequence.
  • the present disclosure provides a specific sgRNA sequence targeting the ACE2 gene.
  • the sgRNA sequence is an isolated sgRNA sequence.
  • the present disclosure provides a targeting vector that specifically targets the ACE2 gene.
  • the targeting vector is an isolated targeting vector.
  • the present disclosure provides a humanized cell line of the ACE2 gene.
  • the present disclosure provides a method for preparing a humanized cell line of ACE2 gene.
  • the present disclosure provides a humanized animal with an ACE2 gene.
  • the present disclosure provides a method for preparing a genetically humanized animal.
  • the present disclosure provides a mouse embryonic stem cell model humanized with the ACE2 gene.
  • the present disclosure provides a primer combination, the primer combination comprising at least 85% or at least 90% or at least 91% or at least 92% or at least 93% of the sequence shown in SEQ ID NO: 19 % Or at least 94% or at least 95% or at least 96% or at least 97% or at least 98% or at least 99% or 100% identical upstream primers and at least 85% of the sequence shown in SEQ ID NO: 20 Or at least 90% or at least 91% or at least 92% or at least 93% or at least 94% or at least 95% or at least 96% or at least 97% or at least 98% or at least 99% or 100% identical downstream primers.
  • the aforementioned primers are isolated primers.
  • the primer combination further includes a combination of at least 85%, or at least 90%, or at least 91%, or at least 92%, or at least 93%, or at least 94%, or at least 95% of the sequence shown in SEQ ID NO: 21 % Or at least 96% or at least 97% or at least 98% or at least 99%, or 100% identical upstream primers and at least 85% or at least 90% or at least 91% with the sequence shown in SEQ ID NO: 22 Or at least 92% or at least 93% or at least 94% or at least 95% or at least 96% or at least 97% or at least 98% or at least 99%, or a downstream primer that is 100% identical.
  • the aforementioned primers are isolated primers.
  • the primer combination further includes a combination of at least 85%, or at least 90%, or at least 91%, or at least 92%, or at least 93%, or at least 94%, or at least the sequence shown in SEQ ID NO: 23 95% or at least 96% or at least 97% or at least 98% or at least 99%, or 100% identical upstream primers and at least 85% or at least 90% or at least 91 with the sequence shown in SEQ ID NO: 24 % Or at least 92% or at least 93% or at least 94% or at least 95% or at least 96% or at least 97% or at least 98% or at least 99%, or 100% identical downstream primers.
  • the aforementioned primers are isolated primers.
  • the primer combination further comprises at least 85% or at least 90% or at least 91% or at least 92% or at least 93% or at least 94% or at least 95% of the sequence shown in SEQ ID NO: 25 % Or at least 96% or at least 97% or at least 98% or at least 99%, or 100% identical upstream primers and at least 85% or at least 90% or at least 91% with the sequence shown in SEQ ID NO: 26 Or at least 92% or at least 93% or at least 94% or at least 95% or at least 96% or at least 97% or at least 98% or at least 99%, or a downstream primer that is 100% identical.
  • the aforementioned primers are isolated primers.
  • the present disclosure provides the application of the primer combination in the preparation of cell lines or cell lines or non-human animals.
  • the aforementioned cells are isolated cells.
  • the animal is a mammal. In some embodiments, the animal is selected from pigs, rats, mice, hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens, cats, horses, dogs, orangutans, or monkeys. In some embodiments, the mammal is a rodent. In some embodiments, the animal is a mouse. In some embodiments, the animal is selected from adult mice. In some embodiments, the animal is selected from fetal mice.
  • the animal is a genetically humanized animal.
  • the gene is ACE2.
  • the present disclosure provides the application of the primer combination in the preparation of targeting vectors.
  • the present disclosure provides a targeting vector, comprising a 5'homology arm sequence, a human ACE2 gene fragment, and a SV40 polyA sequence linked together; the 5'homology arm is linked to the target genome The 5'homology arm where the 5'target sequence at the locus is homologous.
  • the aforementioned targeting vector is an isolated targeting vector.
  • the targeting vector connects the 5'homology arm sequence, the human ACE2 gene fragment and the SV40 polyA sequence by using the primer combination.
  • the targeting vector is used to insert the CDS sequence of the human ACE2 gene into the promoter and 5'UTR region sequence of the animal gene, and then use the animal target gene promoter to promote the expression of the human target gene.
  • the 5'homology arm sequence has at least 85%, or at least 90%, or at least 91%, or at least 92%, or at least 93%, or at least 94%, or the sequence shown in SEQ ID NO: 15 At least 95% or at least 96% or at least 97% or at least 98% or at least 99%, or 100% identity.
  • the CDS sequence of the ACE2 gene has at least 85% or at least 90% or at least 91% or at least 92% or at least 93% or at least 94% or at least the sequence shown in SEQ ID NO: 12 95% or at least 96% or at least 97% or at least 98% or at least 99%, or 100% identity.
  • the SV40 polyA sequence and the sequence shown in SEQ ID NO: 14 have at least 85% or at least 90% or at least 91% or at least 92% or at least 93% or at least 94% or at least 95% Or at least 96% or at least 97% or at least 98% or at least 99%, or 100% identity.
  • the SV40 polyA sequence is located after the CDS sequence.
  • the targeting vector further comprises a 3'homology arm, which is a 3'homology arm that is homologous to the 3'target sequence at the target genomic locus.
  • the targeting vector further comprises at least 85%, or at least 90%, or at least 91%, or at least 92%, or at least 93%, or at least 94%, or at least 95% of the sequence shown in SEQ ID NO: 17. % Or at least 96% or at least 97% or at least 98% or at least 99%, or 100% identity screening marker PGK-Puro.
  • the targeting vector further comprises at least 85%, or at least 90%, or at least 91%, or at least 92%, or at least 93%, or at least 94%, or at least 95% of the sequence shown in SEQ ID NO: 18. % Or at least 96% or at least 97% or at least 98% or at least 99%, or 100% identical Frt sequence.
  • sequence of connection of each sequence fragment of the targeting vector is 5'homology arm sequence, human ACE2 gene fragment, SV40 polyA sequence, frt sequence, PGK-Puro sequence, frt sequence and 3'homology. Arm sequence.
  • the animal is a mammal. In some embodiments, the animal is selected from pigs, rats, mice, hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens, cats, horses, dogs, orangutans, and monkeys. In some embodiments, the mammal is a rodent. In some embodiments, the animal is a mouse. In some embodiments, the animal is selected from adult mice. In some embodiments, the animal is selected from fetal mice.
  • the animal is a genetically humanized animal.
  • the gene is ACE2.
  • the present disclosure provides the application of the targeting vector in the preparation of genetically humanized animal models.
  • the humanized ACE2 mouse model is the original mouse ACE2 site-specific expression hACE2 mouse model, which can simulate the original mACE2 expression characteristics, has tissue specificity, and more rigorously simulates the pathogenesis of human infection 2019-nCoV.
  • the animal is a mammal. In some embodiments, the animal is selected from pigs, rats, mice, hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens, cats, horses, dogs, orangutans, and monkeys. In some embodiments, the mammal is a rodent. In some embodiments, the animal is a mouse. In some embodiments, the animal is selected from adult mice. In some embodiments, the animal is selected from fetal mice.
  • the animal is a genetically humanized animal.
  • the gene is ACE2.
  • the present disclosure provides a method for preparing the targeting vector, which includes the following steps: the 5'homology arms of the product fragments obtained by PCR amplification, human ACE2 CDS and SV40 polyA are PCR into a bridge PCR method. Continuous segment 5arm-hACE-SV40.
  • the PCR reaction system is: 2 ⁇ Phanta Max Buffer is about 25 ⁇ L; dNTP Mix is about 1 ⁇ L; 10 ⁇ M upstream primer is about 2 ⁇ L; 10 ⁇ M downstream primer is about 2 ⁇ L; DNA Polymerase is about 1 ⁇ L; template strand
  • the 5'homology arm, human ACE2 CDS, and SV40 polyA fragments are each about 20-200ng; H 2 O is supplemented to 50 ⁇ L; PCR amplification reaction conditions are about 62-68 °C starting, and each cycle is reduced to about 0.2-0.5 °C.
  • the primers used to amplify the 5'homology arm fragments include at least 85% or at least 90% or at least 91% or at least 92% or at least 93% of the sequence shown in SEQ ID NO: 19. % Or at least 94% or at least 95% or at least 96% or at least 97% or at least 98% or at least 99% or 100% identical upstream primers and at least 85% of the sequence shown in SEQ ID NO: 20 Or at least 90% or at least 91% or at least 92% or at least 93% or at least 94% or at least 95% or at least 96% or at least 97% or at least 98% or at least 99% or 100% identical downstream primers.
  • the primer is an isolated primer.
  • the primers used to amplify the human ACE2 gene fragment include those having at least 85% or at least 90% or at least 91% or at least 92% or at least 93% with the sequence shown in SEQ ID NO: 21 Or at least 94%, or at least 95%, or at least 96%, or at least 97%, or at least 98%, or at least 99%, or an upstream primer that is 100% identical to the sequence shown in SEQ ID NO: 22 and has at least 85% or A downstream primer that is at least 90% or at least 91% or at least 92% or at least 93% or at least 94% or at least 95% or at least 96% or at least 97% or at least 98% or at least 99% or 100% identical.
  • the primer is an isolated primer.
  • the primer used in the SV40 polyA sequence includes a primer that is at least 85% or at least 90% or at least 91% or at least 92% or at least 93% or at least 94% with the sequence shown in SEQ ID NO: 23. Or at least 95%, or at least 96%, or at least 97%, or at least 98%, or at least 99%, or 100% identical upstream primers and at least 85% or at least 90% with the sequence shown in SEQ ID NO: 24 or A downstream primer that is at least 91% or at least 92% or at least 93% or at least 94% or at least 95% or at least 96% or at least 97% or at least 98% or at least 99%, or 100% identical.
  • the primer is an isolated primer.
  • the method further includes the following steps: the 5arm-hACE-SV40 fragment is subjected to double digestion with AgeI+MluI; the 3'homology arm fragment is subjected to double digestion with AscI+HindIII and then connected by digestion. Connect it up, so you have to hit the target carrier.
  • the primers used in the 3'homology arm fragments include at least 85% or at least 90% or at least 91% or at least 92% or at least 93% or the sequence shown in SEQ ID NO: 25 At least 94%, or at least 95%, or at least 96%, or at least 97%, or at least 98%, or at least 99%, or 100% identical upstream primers and at least 85% or at least with the sequence shown in SEQ ID NO: 26
  • a downstream primer that is 90% or at least 91% or at least 92% or at least 93% or at least 94% or at least 95% or at least 96% or at least 97% or at least 98% or at least 99%, or 100% identical.
  • the primer is an isolated primer.
  • the present disclosure provides a method for preparing a humanized animal cell line, in which the primer combination is used.
  • the method includes the use of the targeting vector.
  • the method includes introducing a human-derived gene of interest into an animal cell, so that the gene of interest expresses the CDS of the human-derived gene of interest in the animal cell.
  • the gene of interest is ACE2.
  • the animal is a mammal. In some embodiments, the animal is a rodent. In some embodiments, the animal is a mouse.
  • the cell is an embryonic stem cell.
  • the preparation method includes the following steps: (1) preparing the targeting vector; (2) introducing the prepared targeting vector and the sgRNA-linked vector into animal-derived embryonic stem cells; (3) adding The embryonic stem cells in step (2) are cultured into clones, and then obtained.
  • the sgRNA includes at least 85% or at least 90% or at least 91% or at least 92% or at least 93% or at least 94 % Or at least 95% or at least 96% or at least 97% or at least 98% or at least 99%, or 100% identical sgRNA.
  • the animal is a mammal. In some embodiments, the animal is selected from pigs, rats, mice, hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens, cats, horses, dogs, orangutans, and monkeys. In some embodiments, the mammal is a rodent. In some embodiments, the rodent is a mouse. In some embodiments, the animal is selected from adult mice. In some embodiments, the animal is selected from fetal mice. In some embodiments, the animal is a genetically humanized animal.
  • the gene is ACE2.
  • the present disclosure provides a humanized animal cell line or cell line of ACE2 gene prepared by the method.
  • the cell is a humanized mouse embryonic stem cell.
  • the present disclosure provides a method for preparing a non-human animal, including quoting the above-mentioned primer combination.
  • the preparation method uses the targeting vector.
  • it includes injecting the cells into the animal body.
  • the animal is a mammal. In some embodiments, the animal is selected from pigs, rats, mice, hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens, cats, horses, dogs, orangutans, and monkeys. In some embodiments, the mammal is a rodent. In some embodiments, the rodent is a mouse. In some embodiments, the animal is selected from adult mice. In some embodiments, the animal is selected from fetal mice. In some embodiments, the animal is a genetically humanized animal.
  • the gene is ACE2.
  • the present disclosure provides a non-human animal prepared by the above method.
  • the animal is a mammal. In some embodiments, the animal is selected from pigs, rats, mice, hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens, cats, horses, dogs, orangutans, and monkeys. In some embodiments, the mammal is a rodent. In some embodiments, the rodent is a mouse. In some embodiments, the animal is selected from adult mice. In some embodiments, the animal is selected from fetal mice. In some embodiments, the animal is a genetically humanized animal.
  • the gene is ACE2.
  • the humanized mouse embryonic stem cells include the human ACE2 gene, and the humanized mouse embryonic stem cells can express human full-length ACE2 protein after being specifically differentiated or prepared into a mouse model. Source ACE2 protein expression decreased or disappeared.
  • the present disclosure provides a tissue, body fluid, cell, and fragments or extracts of a humanized mouse or its descendants, and the humanized mouse is prepared by the above-mentioned method.
  • the present disclosure provides a humanized animal model derived from the preparation method or its progeny in the manufacture of human antibodies, or as a model system for pharmacology, immunology, microbiology, and medical research.
  • Figure 1 is a plasmid map of pX330.
  • Figure 2 shows the results of pX330-sgRNA1 construction and sequencing.
  • Figure 3 shows the results of pX330-sgRNA2 construction and sequencing.
  • Figure 4 shows the verification results of pX330-sgRNA1-3 cleavage efficiency.
  • Figure 5 shows the results of pX330-sgRNA3 construction and sequencing.
  • Figure 6 is a schematic diagram of humanized ACE2 targeting strategy.
  • Figure 7 shows the sequencing results of the humanized ACE2 targeting vector.
  • FIG. 8 is a PCR identification diagram of the three-fragment ligation in Comparative Example 1.
  • FIG. Figure 9 is a graph showing the results of PCR identification of humanized ACE2 mouse embryonic stem cell genotypes.
  • Figure 10 is a graph showing the results of PCR identification of the genotype of humanized ACE2 mouse embryonic stem cells after PGK-Puro has been deleted.
  • Figure 11 is a schematic diagram of the humanized ACE2 gene.
  • Figure 12 is a picture of the humanized ACE2 genetically modified mouse formed in Example 8.
  • Figure 13 shows the expression of hACE2 in humanized ACE2 mice detected by qPCR. The results show that humanized ACE2 mice specifically express hACE2, while wild-type mice do not express hACE2.
  • Figure 14 shows the expression of mACE2 in humanized ACE2 mice detected by qPCR. The results show that the expression of mACE2 in hACE2 mice is lacking.
  • FIG. 15 shows the expression of hACE2 protein in the intestinal tissues of hACE2 mice and wild-type ACE2 mice by western blotting. The results show that hACE2 mice express hACE2 protein at the protein level.
  • Figure 16 is a flow chart for preparing mice in Example 10, Test Example 1, Example 11, and Test Example 2.
  • Figure 17 is a flow chart for preparing mice in Example 12, Test Example 3, Example 13, and Test Example 4.
  • Figure 18 is a graph showing the results of the birth rate of mice in Examples 10-13.
  • Fig. 19 is a graph showing the results of the birth rate of mice in Test Example 1-4.
  • CDS is an abbreviation for coding sequence
  • coding sequence refers to any nucleotide sequence used to encode the polypeptide product of a gene.
  • non-coding sequence refers to any nucleotide sequence that does not encode the polypeptide product of a gene.
  • fragment will be understood to mean a nucleotide sequence that is shorter in length than the reference nucleic acid and contains the same nucleotide sequence as the reference nucleic acid in a common part. If appropriate, such nucleic acid fragments according to the present disclosure may be included in a larger polynucleotide, which fragment is a constituent of the larger polynucleotide. Such fragments include at least 6, 8, 9, 10, 12, 15, 18, 20, 21, 22, 23, 24, 25, 30, 39, 40, 42, 45, 48, of the nucleic acid of the present disclosure in length.
  • Corresponding means: (a) a polynucleotide has a nucleotide sequence that is substantially the same or complementary to all or part of the reference nucleotide sequence, or a polynucleotide encoding a peptide or protein The amino acid sequence is exactly the same as the amino acid sequence; or (b) a peptide or polypeptide has an amino acid sequence which is basically the same as the amino acid sequence in the reference peptide or protein.
  • downstream refers to the nucleotide sequence located at the 3'end of the reference nucleotide sequence.
  • the downstream nucleotide sequence usually relates to the sequence after the transcription start point.
  • the translation initiation codon of a gene is located downstream of the transcription initiation site.
  • upstream refers to the nucleotide sequence located at the 5'end of the reference nucleotide sequence.
  • the upstream nucleotide usually refers to a sequence located on the 5'side of the coding sequence or the transcription start point. For example, most promoters are located upstream of the transcription start site.
  • Promoter refers to a DNA sequence capable of controlling the expression of a coding sequence or functional RNA. Generally, the coding sequence is located at the 3'end of the promoter sequence. Promoters can be derived entirely from natural genes, or composed of different elements derived from different promoters found in nature, or even include synthetic DNA fragments. Those skilled in the art should understand that different promoters can direct genes to be expressed in different tissues or cell types, or at different stages of development, or in response to different environmental or physiological conditions.
  • Promoters that cause genes to be expressed most of the time in most cell types are often called “constitutive promoters.” Promoters that cause genes to be expressed in a specific cell type are often referred to as “cell-specific promoters” or “tissue-specific promoters.” Promoters that cause genes to be expressed at a specific stage of development or cell differentiation are usually called “development-specific promoters” or “cell differentiation-specific promoters.” After exposing cells to agents, biomolecules, chemicals, ligands, light, or the like that induce promoters, or treating cells with these substances, promoters that are induced and cause genes to be expressed are often referred to as “ “Inducible promoter” or “regulatory promoter”. It should also be recognized that, because in most cases, the precise boundaries of regulatory sequences have not been fully defined, DNA fragments of different lengths may have the same promoter activity.
  • 5' UTR or "5' non-coding sequence” or “5' untranslated region (UTR)” refers to a DNA sequence located upstream (5') of a coding sequence.
  • restriction endonuclease and “restriction enzyme” refer to enzymes that bind and cleave specific nucleotide sequences within double-stranded DNA.
  • vector means a nucleic acid molecule that can transfer the nucleic acid molecule to which it has been linked.
  • plasmid refers to a circular double-stranded DNA loop into which other DNA segments can be ligated.
  • viral vector in which other DNA segments can be ligated into the viral genome.
  • Certain vectors are capable of self-replication in the host cell into which these vectors are introduced (such as bacterial vectors with a bacterial replication origin and episomal mammalian vectors).
  • Other vectors (such as non-episomal mammalian vectors) can integrate into the genome of the host cell after being introduced into the host cell, and therefore replicate with the host genome.
  • certain vectors can direct the expression of their operatively linked genes.
  • vectors are referred to as "recombinant expression vectors" (or simply “expression vectors") in the present disclosure, and refer to vectors, plasmids, or vectors that are designed so that the inserted nucleic acid sequence can be expressed after being transformed into a host.
  • expression vectors used in recombinant DNA technology are often in the form of plasmids.
  • plasmid and vector are used interchangeably, because plasmid is the most commonly used form of vector.
  • the present disclosure is intended to include other forms of such expression vectors, such as viral vectors (such as replication-defective retroviruses, adenoviruses, and adeno-associated viruses), which serve equivalent functions.
  • Plasmid refers to extrachromosomal elements that often carry genes that are not part of the cell's central metabolism, and are often in the form of circular double-stranded DNA molecules.
  • Such elements can be autonomously replicating sequences, genomic integration sequences, phage or nucleotide sequences from any source, linear, circular or supercoiled, single-stranded or double-stranded DNA or RNA, many of which have been Ligation or recombination into a unique structure that can introduce the promoter fragment and DNA sequence for the selected gene product and the appropriate 3'-end untranslated sequence into the cell.
  • a “targeting vector” or “targeting vector” is a DNA construct containing a sequence "homologous” to the endogenous chromosomal nucleic acid sequence adjacent to the desired genetic modification.
  • the flanking homologous sequence (referred to as “homologous arm”) uses the homology existing between the homologous arm and the corresponding endogenous sequence to direct the targeting vector to a specific chromosomal position in the genome , And introduce the required genetic modification through a process called “homologous recombination”.
  • “Targeting vector” and “targeting vector” can sometimes be used in common.
  • the targeting vector includes the insert nucleic acid and further includes a 5'homology arm and a 3'homology arm, which flanks the insert nucleic acid.
  • the homology arm flanking the inserted nucleic acid corresponds to the nucleic acid in rat, eukaryotic, non-rat eukaryotic, mammal, non-human mammal, human, rodent, non-rat rodent, mouse, or hamster. The region within the target locus.
  • the targeting vector may comprise a first insert nucleic acid flanked by a first homology arm and a second homology arm that are complementary to the first target site and the second target site.
  • the targeting vector thus facilitates the integration of the inserted nucleic acid into rat, eukaryotic, and non-rat true via homologous recombination events that occur between the homologous arm and the complementary target site in the cell's genome.
  • the target locus of the rat, eukaryotic, non-rat eukaryotic, mammal, non-human mammal, human, rodent, non-rat rodent, mouse or hamster nucleic acid comprises A first nucleic acid sequence complementary to the 5'homology arm and a second nucleic acid sequence complementary to the 3'homology arm.
  • the vector can be introduced into the desired host cell by methods known in the art, such as transfection, electroporation, microinjection, transduction, cell fusion, DEAE dextran, calcium phosphate precipitation, lipofection (lysosomal fusion), Use gene gun or DNA carrier transporter (see, for example, Wu et al., 1992, J. Biol. Chem. 267: 963-967; Wu and Wu, 1988, J. Biol. Chem. 263: 14621-14624; and Hartmut et al., Canadian patent application 2,012,311 filed on March 15, 1990).
  • methods known in the art such as transfection, electroporation, microinjection, transduction, cell fusion, DEAE dextran, calcium phosphate precipitation, lipofection (lysosomal fusion), Use gene gun or DNA carrier transporter (see, for example, Wu et al., 1992, J. Biol. Chem. 267: 963-967; Wu and Wu, 1988, J. Biol. Chem
  • transfection refers to the uptake of foreign or heterologous RNA or DNA by a cell.
  • foreign or heterologous RNA or DNA has been introduced into a cell, the cell is “transfected” with such RNA or DNA.
  • the transfected RNA or DNA affects phenotypic changes, the cell is "transformed” by foreign or heterologous RNA or DNA.
  • the transforming RNA or DNA can be integrated (covalently linked into) the chromosomal DNA that constitutes the genome of the cell.
  • homologous means that two sequences of sequences, such as nucleotide or amino acid sequences, have at least about 75% of nucleotides or amino acids, and at least about 80% of nuclei after being optimally aligned and compared.
  • the nucleotides or amino acids, at least about 90-95% of the nucleotides or amino acids, for example, more than 97% of the nucleotides or amino acids are identical.
  • the targeting construct should contain arms that are homologous to the endogenous DNA sequence (ie, "homology arms”); Homologous recombination occurs between the targeted endogenous sequences.
  • homology arms and target sites are complementary to each other when two regions share a sufficient level of sequence identity with each other, thereby serving as substrates for homologous recombination reactions.
  • "Homology” refers to the identity or consensus sequence identity of a DNA sequence with a corresponding or “complementary” sequence.
  • the sequence identity between a given target site and the corresponding homology arm found on the targeting vector can be any degree of sequence identity that allows homologous recombination to occur.
  • the amount of sequence identity shared by the homology arms (or fragments thereof) of the targeting vector and the target site (or fragments thereof) can be at least 51%, 53%, 57%, 60%, 65%, 70% , 75%, 80%, 83%, 85%, 87%, 89%, 91%, 93%, 95%, 97%, 98%, 99% or 100% sequence identity, so the sequence undergoes homology Reorganization.
  • the complementary region of homology between the homology arm and the complementary target site can have any length sufficient to promote homologous recombination at the recognition site of cleavage. Therefore, the homology arm has sufficient homology to the corresponding target site in the cell's genome to perform homologous recombination.
  • the homology arms are referred to herein as 5'homology arms and 3'homology arms. The term relates to the relative position of the homology arm and the inserted nucleic acid in the targeting vector.
  • the homology arm of the targeting vector may have any length sufficient to promote homologous recombination events with the corresponding target site, including, for example, at least 5-10 kb, 5-15 kb, 10-20 kb, 20-30 kb. , 30-40kb, 40-50kb, 50-60kb, 60-70kb, 70-80kb, 80-90kb, 90-100kb, 100-110kb, 110-120kb, 120-130kb, 130-140kb, 140-150kb, 150 -160kb, 160-170kb, 170-180kb, 180-190kb, 190-200kb long or longer.
  • the targeting vector can employ a larger length targeting arm.
  • the sum of the 5'homology arm and the 3'homology arm is at least 10 kb or the sum of the 5'homology arm and the 3'homology arm is at least about 16 kb to about 100 kb or about 30 kb to about 100 kb
  • the total size of the 5'homology arm and the 3'homology arm of the ACE2 is about 10 kb to about 150 kb, about 10 kb to about 100 kb, about 10 kb to about 75 kb, and about 20 kb to about 150 kb.
  • Certain embodiments herein relate to a humanized gene-edited mammal whose genome includes a polyribonucleic acid encoding a human full-length ACE2 protein.
  • the polyribonucleic acid is operably linked to a promoter polyribonucleic acid.
  • the humanized gene-edited mammal does not express all or part of the polyribonucleic acid encoding the endogenous ACE2 protein of the humanized gene-edited mammal, and the polyribonucleic acid encoding the human ACE2 protein
  • the ribonucleic acid includes the modification of the human ACE2 protein gene.
  • the cell is a pluripotent cell, a non-pluripotent cell, a mammalian cell, a human cell, a non-human mammalian cell, a rodent cell, a mouse cell, a hamster cell, a non-human pluripotent cell, or a human multipotent cell.
  • the cell is a primary cell or an immortalized cell.
  • the rodent pluripotent cells are mouse or rat embryonic stem (ES) cells.
  • the animal cell or the human cell is a primary cell or an immortalized cell. In some of the above methods, the animal cell or the human cell is a pluripotent cell. In some of the above methods, the animal pluripotent cells are mouse embryonic stem (ES) cells. In some of the above methods, the human pluripotent cell is a human embryonic stem (ES) cell, a human adult stem cell, a developmentally restricted human progenitor cell, or a human induced pluripotent stem (iPS) cell.
  • ES mouse embryonic stem
  • iPS human induced pluripotent stem
  • certain embodiments herein provide humanized gene-edited cells, especially isolated human and non-human totipotent or pluripotent stem cells, especially mouse embryonic stem cells, which can be used in one or After a variety of continuous genetic modifications in vitro, pluripotency is maintained and the targeted genetic modification can be transmitted to the offspring through the germline.
  • embryo-derived totipotent or pluripotent cells that are capable of promoting the development of any tissue of the embryo after being introduced into the embryo.
  • pluripotent cell as used herein includes undifferentiated cells that have the ability to develop into more than one type of differentiated cell.
  • non-pluripotent cell includes cells that are not pluripotent cells.
  • the targeted gene editing also includes deleting an endogenous nucleic acid sequence at the target genomic locus or inserting the nucleic acid at the target genomic locus.
  • the genetic modification or gene editing includes modification of cells (e.g., eukaryotic cells, non-rat eukaryotic cells, mammalian cells, cell-like cells, non-human mammalian cells, pluripotent cells, non-pluripotent cells).
  • cells e.g., eukaryotic cells, non-rat eukaryotic cells, mammalian cells, cell-like cells, non-human mammalian cells, pluripotent cells, non-pluripotent cells.
  • Two or more modifications independently performed on mouse cells, hamster cells, fibroblasts, or Chinese hamster ovary (CHO) cells.
  • the first modification can be achieved by electroporation or any other method known in the art.
  • an appropriate second nucleic acid construct is used to perform a second modification on the genome of the same cell.
  • the third modification can be achieved by a second electroporation or any other method known in the art.
  • continuous electroporation or any other suitable method known in the art continuously can be used to achieve the third genetic modification, the fourth genetic modification and the fourth genetic modification.
  • Genetic modification, fifth genetic modification, sixth genetic modification, etc. one genetic modification followed by another genetic modification).
  • the present disclosure is a method of homologous recombination of targeting vectors for gene editing, inserting exogenous nucleic acid into the endogenous genome.
  • the inserted nucleic acid comprises inserting a homologous or orthologous human nucleic acid sequence or replacing it with a eukaryotic, non-rat eukaryotic, mammalian, human, or non-human mammalian nucleic acid sequence.
  • the given inserted polynucleotide may be from any organism, including, for example, rodents, non-rat rodents, rats, mice, hamsters, mammals, non-human mammals, eukaryotes , Non-rat eukaryotes, humans, agricultural animals or domestic animals.
  • the insert nucleic acid may comprise a rat-derived nucleic acid, which may comprise fragments of genomic DNA, cDNA, regulatory regions, or any part or combination thereof.
  • the inserted nucleic acid may include those derived from eukaryotes, non-rat eukaryotes, mammals, humans, non-human mammals, rodents, non-rat rodents, humans, rats, and mice. , Hamsters, rabbits, pigs, cows, deer, sheep, goats, chickens, cats, dogs, white melt, primates (for example, marmosets, rhesus monkeys), domestic mammals or agricultural mammals or any other The nucleic acid of the target organism.
  • the insert nucleic acid employed in various methods and compositions can cause the "humanization" of the target locus of interest.
  • the genetic modification is the addition of a nucleic acid sequence.
  • the insert nucleic acid comprises a genetic modification in the coding sequence.
  • the genetic modification includes a deletion mutation of the coding sequence.
  • the genetic modification includes the fusion of two endogenous coding sequences.
  • the insert nucleic acid comprises inserting a homologous or orthologous human nucleic acid sequence or replacing it with a eukaryotic, non-rat eukaryotic, mammalian, human, or non-human mammalian nucleic acid sequence.
  • the inserted nucleic acid comprises inserting a homologous or orthologous human nucleic acid sequence or replacing a mouse DNA sequence with the coding region of an endogenous mouse gene containing a corresponding mouse DNA sequence. In some embodiments, the inserted nucleic acid comprises inserting a homologous or orthologous human nucleic acid sequence or replacing a mouse DNA sequence with the coding region of an endogenous mouse gene containing a corresponding mouse DNA sequence. In some embodiments, a targeting vector is used to target the mouse ACE2 site, and the hACE2 sequence is inserted at the EXON1 CDS start ATG site next to the MACE2.
  • the nucleic acid sequence of the targeting vector may comprise a genetically modified polynucleotide that will generate a region of the ACE2 locus of mammals, humans, or non-human mammals when integrated into the genome, wherein the ACE2 gene Genetic modification at the seat causes a decrease in ACE2 activity, an increase in ACE2 activity, or an adjustment in ACE2 activity.
  • the gene producing ACE2 is completely replaced.
  • the insert nucleic acid may comprise regulatory elements, including, for example, a promoter, enhancer, or transcription.
  • the corresponding replacement region of a given inserted polynucleotide and/or mammalian, human cell, or non-human mammalian locus can be a coding region, an intron, an exon, an untranslated region, and a regulatory region. , Promoter or enhancer or any combination thereof.
  • Target polynucleotides into a target locus, as outlined above, introduction of sequences, resulting in gene-edited cells.
  • “Introduction” presents the sequence into the cell (polypeptide or polynucleotide) in such a way that the sequence enters the interior of the cell.
  • the cells are derived from eukaryotes, non-rat eukaryotes, mammals, non-human mammals, humans, rodents, non-rat rodents, rats, mice, or hamsters.
  • the cell is a eukaryotic cell, a non-rat eukaryotic cell, a pluripotent cell, a non-pluripotent cell, a non-human pluripotent cell, a non-human mammalian cell, a human pluripotent cell, or a human ES Cells, human adult stem cells, growth-restricted human progenitor cells, human induced pluripotent cells (iPS) cells, mammalian cells, human cells, fibroblasts, rodent cells, non-rat rodent cells, rat cells , Mouse cells, mouse ES cells, hamster cells or CHO cells.
  • iPS human induced pluripotent cells
  • the cell employed in the method has a DNA construct stably incorporated into its locus.
  • "Stably incorporated” or “stably introduced” refers to the introduction of a polynucleotide into a cell so that the nucleotide sequence is integrated into the cell's genome and can be inherited by its progeny.
  • the introduction of one or more polynucleotides into the cell is performed by electroporation, intracytoplasmic injection, viral infection, adenovirus, lentivirus, retrovirus, transfection, lipid-mediated transfection Dye-mediated, or mediated by NucleofectionTM.
  • the expression construct is introduced with the introduced nucleic acid.
  • the introduction of the one or more polynucleotides into the cell may be performed multiple times over a period of time. In some embodiments, the introduction of the one or more polynucleotides into the cell can be performed at least twice over a period of time, performed at least three times over a period of time, performed at least four times over a period of time, and performed over a period of time. At least five times, at least six times over a period of time, at least seven times over a period of time, at least eight times over a period of time, at least nine times over a period of time, at least ten times over a period of time, and at least ten times over a period of time.
  • execute at least 12 times over a period of time execute at least 13 times over a period of time, execute at least 14 times over a period of time, execute at least 15 times over a period of time, execute at least 16 times over a period of time, and execute at least 16 times over a period of time. It should be executed at least 17 times over a period of time, at least 18 times over a period of time, at least 19 times over a period of time or at least 20 times over a period of time.
  • the targeting vector (containing the introduced nucleic acid) and the expression vector (containing sgRNA) are introduced into the cell at the same time.
  • a method for manufacturing a humanized non-human animal which comprises: (a) modifying the genome of a pluripotent cell with a targeting vector comprising an inserted nucleic acid to form a donor cell, the inserted nucleic acid Comprising a human nucleic acid sequence; (b) introducing the donor cell into a host embryo; and (c) gestating the host embryo in a surrogate mother, wherein the surrogate mother produces offspring comprising the human nucleic acid sequence.
  • the donor cell is introduced into a host embryo at the blastocyst segment or at the pre-morula stage (ie, 4-cell stage or 8-cell stage).
  • the genetic modification can be transmitted via the germline.
  • a method for producing a humanized mouse comprising: (a) introducing a targeting vector containing ACE2 gene fragments and an expression vector linked to sgRNA into mouse embryonic cells , Forming a gene-edited donor cell; (b) introducing the donor cell into a mouse embryo; and (c) gestating the mouse embryo in a surrogate mother, wherein the surrogate mother produces the human ACE2 The descendants of the sequence.
  • tetraploid complementation technology and “tetraploid embryo compensation technology” or “tetraploid embryo complementation method” or “tetraploid embryo complementation method” can be equivalent, which refers to the combination of a certain number of embryonic stem cells (ES) cells are chimerized with tetraploid embryos.
  • ES embryonic stem cells
  • ES cells and tetraploid embryos are not randomly distributed, that is, the tetraploid embryo part only participates in the yolk sac endoderm and placental trophoblast Cells (such as chorionic ectoderm, trophoblast cells, etc.) and other extra-embryonic tissues, while ES cells are widely involved in the formation of embryonic bodies, allantoic, amniotic membrane, yolk sac mesoderm and chorionic mesoderm. Participate in the generation of yolk sac endoderm and placental trophoblast cell lineages, that is, the developmental potential of the two are complementary. This phenomenon is called tetraploid complementation technology.
  • embryo refers to tissues and cells derived from an animal subject at any time before birth or from an animal subject at any time before birth.
  • embryo is used to describe a fertilized oocyte that is transplanted into the uterus before becoming a fetus eight weeks after fertilization.
  • the fertilized oocyte before transplantation is usually called pre-embryo.
  • pre-embryo the fertilized oocyte before transplantation.
  • embryo which includes the pre-embryonic stage. Therefore, it includes all developmental stages from oocyte fertilization to morula, blastocyst stage incubation and implantation.
  • the embryo is approximately spherical and consists of one or more cells (blastomeres) surrounded by a gelatin-like shell.
  • the acellular matrix is called the zona pellucida.
  • the zona pellucida performs multiple functions until the embryo hatches, and the zona pellucida is a good mark for embryo evaluation.
  • the band is spherical and translucent, and should be clearly distinguished from cell debris.
  • the mammalian pre-implantation embryos have a diameter of about 90-120 microns, and the outer bread has clearly visible zona pellucida composed of glycoproteins. On one side of the fertilized egg, 1-2 polar bodies formed during meiosis can be seen.
  • the cells of 2-cell stage embryos are nearly elliptical and basically the same size.
  • two blastomeres can fuse into a quadruploid cell, and then develop into a quadruploid embryo.
  • the fertilized egg is divided into two to form two blastomeres, namely the 2-cell stage.
  • the two blastomeres are divided into two to form 4, namely the 4-cell stage; and then divided into two into 8 blastomeres.
  • the 8-cell stage after 5 divisions to 32 cells, a "morula is formed.
  • 4 blastomeres can be seen in a staggered arrangement.
  • the 8-cell stage blastomeres are arranged in a staggered arrangement. Divided into upper and lower layers, as tight junctions are formed, densification begins to appear.
  • the 16-cell stage is called morula, and the inner cell mass and trophoblast differentiation appear.
  • 72 hours after fertilization the embryo develops to the 32-cell stage and cleavage There are gaps between the balls, which enlarge to form a complete blastocyst cavity.
  • One side of the cavity is concentrated with a group of cells, which is the inner cell group.
  • a layer of flat cells around the blastocyst cavity is called the trophoblast.
  • the blastocyst is also called the blastocyst.
  • the late blastocyst expands and extrudes the zona pellucida, which is the hatching blastocyst.
  • embryo is used to refer to the following stages-fertilized oocyte, zygote, 2-cell, 4-cell, 8-cell, 16-cell, morula, blastocyst, expanded blastocyst, and hatch The blastocyst, and all the stages in between (e.g. 3-cell or 5-cell).
  • chimera blastocyst or “chimera embryo” as used herein refers to a blastocyst or embryo in a chimeric state containing embryonic stem cells.
  • chimeric blastocysts or embryos by injection methods, they can also be produced using, for example, the so-called “aggregation method", in which embryo + embryo or embryo + cells are made close to each other in a petri dish Adhesion to produce chimeric blastocysts.
  • the relationship between the recipient blastocyst or embryo and the cell to be transplanted in the present disclosure may be an allogeneic relationship or a xenogeneic relationship.
  • administration refers to a method or way of placing cells in a subject by locating cells at least partially at a desired site to produce a desired effect.
  • sgRNA1 sequence (SEQ ID NO:1): 5’-tactgctcagtccctcaccgagg-3’
  • the BbsI restriction site was introduced to synthesize the upstream and downstream annealing primers of sgRNA for subsequent annealing experiments.
  • the sequence of the upstream and downstream single-stranded primers for synthesizing sgRNA1 is as follows:
  • Source of pX330 plasmid pX330 vector map, see Figure 1.
  • the plasmid skeleton comes from Miaoling Plasmid Platform, catalog number P0123.
  • the above-mentioned sgRNA annealing primers were annealed and then respectively connected to the pX330 plasmid (the plasmid was linearized with BbsI first) to obtain the expression vector pX330-sgRNA1.
  • reaction conditions are: ligate at 16°C for more than 30 minutes, transform into 30 ⁇ L of TOP10 competent cells, then take 200 ⁇ L to spread on Amp resistant plates, incubate at 37°C for at least 12 hours, select 2 clones to inoculate Amp resistant LB culture In base (5mL), shake culture at 37°C and 250rpm for at least 12 hours.
  • the randomly selected clones were sent to a sequencing company for sequencing verification.
  • the sequencing results are shown in Figure 2.
  • the correct expression vector pX330-sgRNA1 was selected for subsequent experiments.
  • sgRNA2-sequence (SEQ ID NO: 2): 5’-cttggcattttcctcggtgaggg-3’
  • the BbsI restriction site was introduced to synthesize the upstream and downstream annealing primers of sgRNA for subsequent annealing experiments.
  • the sequence of the upstream and downstream single-stranded primers for synthesizing sgRNA2 is as follows:
  • Source of pX330 plasmid pX330 vector map, see Figure 1.
  • the plasmid skeleton comes from Miaoling Plasmid Platform, catalog number P0123.
  • the above-mentioned sgRNA annealing primers After annealing the above-mentioned sgRNA annealing primers, they were respectively connected to the pX330 plasmid (the plasmid was linearized with BbsI first) to obtain the expression vector pX330-sgRNA2.
  • reaction conditions are: ligate at 16°C for more than 30 minutes, transform into 30 ⁇ L of TOP10 competent cells, then take 200 ⁇ L to spread on Amp resistant plates, incubate at 37°C for at least 12 hours, select 2 clones to inoculate Amp resistant LB culture In base (5mL), shake culture at 37°C and 250rpm for at least 12 hours.
  • the randomly selected clones were sent to a sequencing company for sequencing verification.
  • the sequencing results are shown in Figure 3.
  • the correct expression vector pX330-sgRNA2 was selected for subsequent experiments.
  • Example 2 ⁇ g of pX330-sgRNA plasmids prepared in Example 1 and Example 2 were transfected into mouse embryonic stem cells using the Lipofectamine 3000 (Invitrogen, catalog number L3000001) method.
  • Lipofectamine 3000 Invitrogen, catalog number L3000001
  • the mouse embryonic stem cells after two days of transfection were collected, and the genome was extracted with the cell genome extraction kit (Tiangen, DP304-02).
  • the PCR upstream and downstream primers were designed on both sides of the genome cutting site, and the upstream primer (5arm-sgF: ggttttgatttggccataaaatgttagc (SEQ ID NO: 10)) and the downstream primer (3arm-sgR: attcccaggtccagtttcacctaag (SEQ ID NO: 11)) were paired to extract the result.
  • Genome PCR reaction using Novozan Phanta Max Super-Fidelity DNA Polymerase).
  • T7 endonuclease I (Biolabs, M0302L) to verify the cutting efficiency of pX330-sgRNA, the principle T7 endonuclease I can recognize and cut incompletely matched DNA.
  • the genome was extracted from the cells transfected with pX330-sgRNA1 and pX330-sgRNA2, and the PCR products amplified by 5arm-sgF+3arm-sgR were recovered (Tiangen, DP214-02), and 1 ⁇ g was taken for annealing reaction. As follows:
  • PCR product 1 ⁇ g Buffer 2 2 ⁇ L H 2 O Make up to 20 ⁇ L Reaction conditions Boil in a water bath for 10 minutes and then cool down naturally
  • the cutting bands of sgRNA1 and sgRNA2 of Example 1 and Example 2 are brighter (sgRNA1 can be cut into two bands of about 376bp and 581bp, and sgRNA2 can be cut into two bands of about 371bp and 586bp), and have high cutting efficiency.
  • sequences of the upstream and downstream single-stranded primers for the synthesis of sgRNA3 are as follows:
  • Example 2 The remaining steps are the same as in Example 1.
  • the clones were randomly selected and sent to a sequencing company for sequencing verification.
  • the sequencing results are shown in Figure 5.
  • the correct expression vector pX330-sgRNA3 was selected for subsequent experiments.
  • the human ACE2 gene (Gene ID: ID: 59272) CDS protein coding sequence (based on the transcript with NCBI accession number NM_001371415.1 ⁇ NP_001358344.1, the CDS sequence (hACE2-CDS) is shown in SEQ ID NO: 12.
  • the protein sequence hACE2-protein is shown in SEQ ID NO: 13
  • the mouse Ace2 promoter is used to promote human ACE2 gene expression.
  • the inserted human ACE2 CDS sequence is followed by the SV40 polyA sequence signal (SV40-polyA sequence is shown in SEQ ID NO: 14) termination signal to strengthen human ACE2 mRNA transcription stop.
  • the inventors further designed the targeting scheme shown in Figure 6 and a vector containing a 5'homology arm (5arm), a human ACE2 gene fragment, and a 3'homology arm (3arm).
  • the 5'homology arm is the 125683-126652 nucleotides of the NCBI accession number AC091606.8 (the 5'homology arm sequence is shown in SEQ ID NO: 15)
  • the 3'homology arm is the NCBI accession number Nucleotides 126796-127766 of AC091606.8 (the sequence of the 3'homology arm is shown in SEQ ID NO: 16).
  • the PGK-puromycin heterogeneous gene package is also inserted into the vector for screening.
  • the puromycin resistance gene (PGK-puro, SEQ ID NO: 17) expression box is designed with a pair of frt sites in the same direction ( SEQ ID NO: 18), therefore, FLP recombinase can be used to remove to solve the safety problem caused by transgene.
  • the constructed vector was subjected to complete sequence verification. Before targeting, the vector is linearized by AgeI (a schematic diagram of a targeting vector and a schematic diagram of a targeting strategy are shown in Figure 6).
  • the vector construction process is as follows:
  • an upstream primer (5arm-pcrF: tcgcacacattccacatccaccggtccctatggagtggagaagagtctta (SEQ ID NO: 19)) to amplify the bridge fragment of the 5'homology arm and a matching downstream primer
  • an upstream primer (5arm-pcrF: tcgcacacattccacatccaccggtccctatggagtggagaagagtctta (SEQ ID NO: 19)
  • a matching downstream primer (5arm-pcrR: gaaggagccaggaagagcttgacatctttccccgtgcgccaagagcttgacatctttccgtg20gcca ID NO: 19);
  • hACE2-F ggatcttggcgcacggggaaagatgtcaagctcttcctggctctttc (SEQ ID NO: 21)
  • hACE2-R cattataagctgcaataaacaagttctaaNO:22ggtctga ID
  • an upstream primer (SV40-F: gatgatgttcagacctccttttagaacttgtttattgcagcttataatg (SEQ ID NO: 23)) to amplify the bridge fragment of SV40 polyA and a matching downstream primer (SV40-R: AGAGAATAGGAACTTCGCACGCGTtaagatacattgatgatgagt;
  • an upstream primer (3arm-pcrF: tacgaagttatGtcgacgcGGCGCGCCgaattataatactaacattactg (SEQ ID NO: 25)) for amplifying the 3'homology arm fragment and a matching downstream primer (3arm-pcrR: tatgaccatgattacgccaagcttaagaccaaactattagattacgccaagcttaagaccaaactatta:cgcagtta ID 26).
  • the amplification template of the 5'homology arm and the 3'homology arm is C57BL6/J mouse genome
  • the amplification template of human ACE2 is human lung cell cDNA.
  • the PCR reaction system (using Novozan Phanta Max Super-Fidelity DNA Polymerase) and conditions are shown in Table 4:
  • the 5arm-hACE-SV40 fragment was digested with AgeI+MluI double digestion; the 3'homology arm fragment was digested with AscI+HindIII double digestion and then connected by restriction digestion and ligation respectively, so as to obtain the targeting vector.
  • the obtained positive targeting vector will be sent for sequencing and identification.
  • the sequencing company has verified that the sequence is correct (as shown in Figure 7), thus successfully obtaining the humanized ACE2 targeting vector.
  • the entire targeting vector sequence is as SEQ ID NO: 27 Shown.
  • the 5'homology arm of the product fragments amplified by PCR, human ACE2 CDS, and SV40 polyA were PCR into a continuous fragment 5arm-hACE-SV40 using the overlap PCR method.
  • the PCR reaction conditions are shown in Table 5, and the rest of the conditions are the same. Example 4.
  • the humanized ACE2 mouse embryonic stem cells can be obtained according to the following method:
  • C57BL6/J mouse embryonic stem cells (the embryonic stem cells are derived from established embryonic stem cell lines) are recovered from the liquid nitrogen cryopreserved cell bank, especially using mouse embryonic stem cells within the passage number of p10, cultured at 6 cm Culture and grow in a dish for 3 days.
  • the puromycin-resistant mouse embryonic stem cells were cloned and cultured in 96-well plates by using a glass puller to draw a single clone.
  • the single clone was trypsinized and divided into two parts.
  • One part of the cells was separately lysed in 10 ⁇ L of NP 40 lysis buffer at 56° C. for 60 minutes, and then at 95° C. for 10 minutes.
  • mouse embryonic stem cell culture prepare feeder layer feeder cells one day in advance, spread them in different well plates as required, and culture them overnight to form a monolayer.
  • the feeder cells are mouse embryonic fibroblasts prepared by the mitomycin C (MMC) method.
  • MMC mitomycin C
  • the density is about 300,000 centimeter plates and 100,000 per hole for 6-well plates.
  • composition of mES+LIF+2i medium is: Knockout DMEM(1 ⁇ ,gibco)+15%FBS(FRONT BIOMEDICAL,0.22 ⁇ m Millipore filter filtration)+GlutaMAX(100 ⁇ ,gibco)+NEAA(100 ⁇ ,gibco)+P /S(P:50units,S:50mg/ml,Hyclone)+ ⁇ -mercaptoethanol(gibco, use concentration 0.1mM)+LIF(1000units/ml,Millipore)+CHIR99021(GSK3 ⁇ inhibitor, use concentration 3 ⁇ M)+PD0325901( MEK inhibitor, used at a concentration of 1 ⁇ M).
  • composition of NP40 lysate is: 10mL TE (20mM Tris pH8.0, 150mM NaCl, 2mM EDTA) + 0.5% NP40 + 10 ⁇ L proteinase K (10mg/mL).
  • pX330-sgRNA1 is replaced with pX330-sgRNA2 or pX330-sgRNA3, and the other steps are the same as pX330-sgRNA1.
  • Table 6 shows the targeting effects of pX330-sgRNA1, pX330-sgRNA2 and pX330-sgRNA3 with targeting vectors.
  • the cell lysate finally obtained in Example 6 was used as a template for PCR screening for genotyping.
  • Phanta Max Super-Fidelity DNA Polymerase reagent Nolegin
  • PCR screening was carried out according to the manufacturer's instructions.
  • PCR analysis was used for the HDR with 5'homology arm and 3'homology arm for targeted insertion into the mouse Ace2 site. Since the ACE2 gene is located on the X chromosome and the mouse embryonic stem cells used are XY males, there is no biallelic targeting.
  • the upstream of the targeted insertion primer is located inside the puromycin resistance (Puro-F: aacctccccttctacgagc (SEQ ID NO: 28)), and the downstream of the primer paired with it is located on the outer side of the 3'homology arm (3arm-outR: tacagccaggatctggatgtcagc (SEQ ID NO:29)). If the insertion position of the recombinant vector is correct, a band with a length of 1504bp should appear. At this time, the genome sequence of the mouse embryonic stem cell Ace2 locus was replaced with SEQ ID NO: 30.
  • the PCR identification results are shown in Figure 9. A total of 14 clones were identified, of which the positive clones marked with *, and the PCR products matched the sequencing results.
  • the mouse embryonic stem cell with a positive PCR result was cloned into a successfully edited humanized mouse embryonic stem cell model, but it still retains the PGK-Puro screening mark. Because the two ends of PGK-Puro have a pair of frt sites in the same direction, Therefore, FLP recombinase can be used to remove to solve the safety problem caused by transgene.
  • the method for deleting the PGK-Puro screening flag is as follows:
  • mice embryonic stem cells with positive PCR results to a 6cm plate, and use the Nucleofector TM IIs/2b electroporator and Mouse ES Cell Kit (Lonza, VPH-1001) mouse embryonic stem cell electroporation kit, using A023 program, about 2 ⁇ 10 6 cells were electroporated, and the electroporation process contained 100 ⁇ L electroporation buffer of pPGK-FLPo plasmid (Addgene, 13793) In liquid.
  • the transfected cells were planted into 6 wells of a 12-well plate. After 3 days, the mouse embryonic stem cell clones were picked up by a glass puller to draw a single clone and cultured in a 96-well plate.
  • Clones corresponding to puromycin intolerance can use upstream primers (hACE2-F: tgatagtggttggcattgt (SEQ ID NO: 31)) and downstream primers (3arm-outR: tacagccaggatctggatgtcagc (SEQ ID NO: 29)) for genomic genotyping PCR Identification.
  • the length of the PCR product is 1532 bp
  • the length of the PCR product before PGK-Puro is deleted is 2863 bp.
  • the genotype identification results are shown in Fig. 9.
  • the 1500bp band in the gel running band is the clone after successfully deleting PGK-puro
  • the band at 3000bp is the clone before deletion.
  • the clone corresponding to puromycin intolerance is the mouse embryonic stem cell that was finally successfully edited to target humanized ACE2, that is, the mouse embryonic stem cell finally obtained the humanized ACE2 gene as shown in Figure 10.
  • the genomic sequence of the mouse embryonic stem cell Ace2 locus was replaced with the sequence shown in SEQ ID NO:32.
  • Example 8 The formation of humanized ACE2 genetically modified mice
  • mice 4. Cultured overnight in a CO 2 incubator, transplanted into the uterus of E2.5-day pseudo-pregnant mice. After 17 days, the surrogate mice were euthanized by cervical dislocation and then subjected to laparotomy. The surviving and breathing newborn mice were put into the baby cage Within 21 days, weaned and obtained transgenic mice completely derived from embryonic stem cells, namely humanized ACE2 genetically modified mice ( Figure 12).
  • Newborn humanized ACE2 mice and wild-type mice were dissected, the lungs, kidneys, and intestines were taken out, and they were lysed with Trizol, and then RNA was extracted with the cell/tissue total RNA extraction kit (Novizan, RC101-01 ) And reverse with HiScript II Q RT SuperMix for qPCR reagents (Novizan, R222-01).
  • hACE2 specific primers hACE2-qF: TGATAGTGGTTGGCATTGT, hACE2-qR: CGATGGAGGCATAAGGATT
  • mACE2 specific primers mACE2-qF: GGTTGGCATCATCATCCT; mACE2-qR: GTCTGAGCATCATCACTGT
  • the mouse embryonic stem cells used in this example are the puromycin intolerant humanized ACE2-targeted mouse embryonic stem cells obtained in the above examples 6 and 7. In the specific experiment, it was recovered from the cryopreserved cell bank in liquid nitrogen, especially using embryonic stem cells within the generation number of p15, and cultured and grown in a 6cm culture dish for 3 days. In this example, embryonic stem cells of passage 12 are used.
  • Electrofusion fluid formula (electrofusion fluid with increased Mg 2+ and Ca 2+ concentration)
  • mice were euthanized by cervical dislocation.
  • the mice's abdomen was disinfected with 70% alcohol, and the abdominal skin and muscle layer were cut with excipient forceps and ophthalmic scissors to open the abdominal cavity.
  • Grasp the upper part of a uterine horn with forceps use scissors to make a small opening in the membrane near the fallopian tube, cut off the junction between the fallopian tube and the ovary, move the fallopian tube and the attached uterus to a 35mm petri dish, and fix the fallopian tube fimbria with the forceps
  • a flushing needle filled with M2 culture medium Hogan, 1994
  • wash the oviduct with 0.1 mL of M2 culture medium
  • the tetraploid embryo develops to the 2-cell stage, the zona pellucida is removed with acid Tyrode's solution, and the small clusters of embryonic stem cells digested with 0.25% trypsin are aggregated, and then cultured for 24 hours to form a chimeric embryo.
  • the chimeric embryos are transferred to the uterus of pseudo-pregnant mice at 2.5 days of pregnancy, and full-term newborn mice can be obtained after 17 days.
  • tetraploid embryos can only effectively form extra-embryonic tissues such as placenta, newborn mice obtained from chimeras of tetraploid embryos and embryonic stem cells are entirely derived from embryonic stem cells.
  • FIG. 16 The schematic diagram of the process of preparing mice in this example is shown in FIG. 16.
  • the results of the mouse birth rate are shown in Figure 18. It can be seen from Figure 18 that the survival rate of the mice prepared by the method of Example 10 reached 25% (10/40).
  • mouse embryonic stem cells are ordinary embryonic stem cells that have not been genetically modified.
  • the acquisition is carried out as follows: C57BL6/J mouse embryonic stem cells are recovered from the cryopreserved cell bank in liquid nitrogen, and mice with generation number p12 are used Embryonic stem cells were cultured and grown in a 6cm petri dish for 3 days.
  • FIG. 16 A schematic diagram of the process of preparing mice is shown in FIG. 16. The results of the mouse birth rate are shown in Fig. 19, and it can be seen from Fig. 19 that the survival rate of the mice prepared by the method of Test Example 1 reached 33.3% (48/144).
  • the mouse embryonic stem cells used in this example are the puromycin intolerant humanized ACE2-targeted mouse embryonic stem cells obtained in the above examples 6 and 7. In the specific experiment, it was recovered from the cryopreserved cell bank in liquid nitrogen, especially using embryonic stem cells within the generation number of p15, and cultured and grown in a 6cm culture dish for 3 days. In this example, embryonic stem cells of passage 12 are used.
  • the KSOM medium and M2 medium are the same as in Example 10.
  • Tetraploid embryos develop to the 2-cell stage, remove the zona pellucida with acid Tyrode's solution, aggregate with small clusters of embryonic stem cells digested with 0.25% trypsin, and then culture for 24 hours to form chimeric embryos, or culture for 48 hours
  • embryonic stem cells are injected into the blastocyst cavity through micromanipulation (Nagy et al., 1993).
  • FIG. 16 A schematic diagram of the process of preparing mice is shown in FIG. 16. The results of the birth rate of mice in this implementation are shown in FIG. 18. It can be seen from Figure 18 that the survival rate of mice was 14.2% (15/106).
  • Example 11 Except that the acquisition of embryonic stem cells is different from that in Example 11, the other operations are the same as in Example 11.
  • mouse embryonic stem cells are ordinary embryonic stem cells that have not been genetically modified.
  • the acquisition is carried out as follows: C57BL6/J mouse embryonic stem cells are recovered from the cryopreserved cell bank in liquid nitrogen, and mice with generation number p12 are used Embryonic stem cells were cultured and grown in a 6cm petri dish for 3 days.
  • FIG. 16 A schematic diagram of the process of preparing mice is shown in FIG. 16.
  • the result of the mouse birth rate is shown in Fig. 19, and it can be seen from Fig. 19 that the survival rate of the mouse is 21.1% (32/152).
  • Example 12 Preparation method of mice (4-cell stage/electrofusion solution group with increased Mg 2+ and Ca 2+ concentrations)
  • the mouse embryonic stem cells used in this example are the puromycin intolerant humanized ACE2-targeted mouse embryonic stem cells obtained in the above examples 6 and 7. In the specific experiment, it was recovered from the cryopreserved cell bank in liquid nitrogen, especially using embryonic stem cells within the generation number of p15, and cultured and grown in a 6cm culture dish for 3 days. In this example, embryonic stem cells of passage 12 are used.
  • the KSOM medium and M2 medium are the same as in Example 10.
  • the pregnant mouse will be euthanized by cervical dislocation.
  • the abdomen of the mouse will be sterilized with 70% alcohol, and the abdominal skin and muscle layer will be cut with excipient forceps and ophthalmic scissors to open the abdominal cavity.
  • Grasp the upper part of a uterine horn with forceps use scissors to make a small opening in the membrane near the fallopian tube, cut off the junction between the fallopian tube and the ovary, move the fallopian tube and the attached uterus to a 35mm petri dish, and fix the fallopian tube fimbria with the forceps
  • a flushing needle filled with M2 culture medium Hogan, 1994
  • wash the fallopian tube with 0.1ml of M2 culture medium collect the flushed embryos with a pipette and wash them with M2 3 times to collect E1.
  • Tetraploid embryos develop to the 4-cell stage, remove the zona pellucida with acid Tyrode's solution, aggregate with small clusters of embryonic stem cells digested with 0.25% trypsin, and then culture for 24 hours to form chimeric embryos, or culture for 48 hours
  • embryonic stem cells are injected into the blastocyst cavity through micromanipulation (Nagy et al., 1993).
  • Electrofusion fluid formula (electrofusion fluid with increased Mg2+ and Ca2+ concentration)
  • FIG. 17 A schematic diagram of the process of preparing mice is shown in FIG. 17.
  • Example 12 Except that the acquisition of embryonic stem cells is different from that in Example 12, the other operations are the same as in Example 12.
  • mouse embryonic stem cells are ordinary embryonic stem cells that have not been genetically modified.
  • the acquisition is carried out as follows: C57BL6/J mouse embryonic stem cells are recovered from the cryopreserved cell bank in liquid nitrogen, and mice with generation number p12 are used Embryonic stem cells were cultured and grown in a 6cm petri dish for 3 days.
  • FIG. 17 A schematic diagram of the process of preparing mice is shown in FIG. 17.
  • the results of the birth rate of mice are shown in Fig. 19, and it can be seen from Fig. 19 that the survival rate of mice is 7.5% (9/120).
  • the mouse embryonic stem cells used in this example are the puromycin intolerant humanized ACE2-targeted mouse embryonic stem cells obtained in the above examples 6 and 7. In the specific experiment, it was recovered from the cryopreserved cell bank in liquid nitrogen, especially using embryonic stem cells within the generation number of p15, and cultured and grown in a 6cm culture dish for 3 days. In this example, embryonic stem cells of passage 12 are used.
  • the KSOM medium and M2 medium are the same as in Example 10.
  • the pregnant mouse will be euthanized by cervical dislocation.
  • the abdomen of the mouse will be sterilized with 70% alcohol, and the abdominal skin and muscle layer will be cut with excipient forceps and ophthalmic scissors to open the abdominal cavity.
  • Grasp the upper part of a uterine horn with forceps use scissors to make a small opening in the membrane near the fallopian tube, cut off the junction between the fallopian tube and the ovary, move the fallopian tube and the attached uterus to a 35mm petri dish, and fix the fallopian tube fimbria with the forceps
  • a flushing needle filled with M2 culture medium Hogan, 1994
  • wash the fallopian tube with 0.1ml of M2 culture medium collect the flushed embryos with a pipette and wash them with M2 3 times to collect E1.
  • Tetraploid embryos develop to the 4-cell stage, remove the zona pellucida with acid Tyrode's solution, aggregate with small clusters of embryonic stem cells digested with 0.25% trypsin, and then culture for 24 hours to form chimeric embryos, or culture for 48 hours
  • embryonic stem cells are injected into the blastocyst cavity through micromanipulation (Nagy et al., 1993).
  • mice The process and results of the preparation of mice in Example 5 are shown in FIG. 17. It can be seen from Figure 17 that the production efficiency of mice is very low. Further, the results of the birth rate of mice are shown in FIG. 18. It can be seen from Figure 18 that the survival rate of mice is only 0.3% (1/350).
  • Example 13 Except that the acquisition of embryonic stem cells is different from that in Example 13, the other operations are the same as in Example 13.
  • mouse embryonic stem cells are ordinary embryonic stem cells that have not been genetically modified.
  • the acquisition is carried out as follows: C57BL6/J mouse embryonic stem cells are recovered from the cryopreserved cell bank in liquid nitrogen, and mice with generation number p12 are used Embryonic stem cells were cultured and grown in a 6cm petri dish for 3 days.
  • FIG. 17 A schematic diagram of the process of preparing mice is shown in FIG. 17.
  • the result of the mouse birth rate is shown in Figure 19, and it can be seen from Figure 19 that the survival rate of the mouse is only 2.5% (4/163).

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Abstract

提供了一种动物的制备方法及应用。该方法包括将四倍体胚胎与胚胎干细胞聚合形成新的重构胚或嵌合体胚胎，该四倍体胚胎为发育到2-细胞期的四倍体胚胎。利用2-细胞期的四倍体胚胎与胚胎干细胞聚合，改善了四倍体补偿技术制作小鼠的效率稳定性差，对来自纯系小鼠的胚胎干细胞效率低下的问题，提升了小鼠出生率，接近正常胚胎移植，且可以从干细胞直接制造出胚胎和成年鼠进行表型研究。

Description

一种动物的制备方法 技术领域
本公开属于生物医药领域，涉及一种动物的制备方法。
背景技术
实验动物疾病模型对于研究人类疾病发生的病因、发病机制、开发防治技术和治疗药物是不可缺少的研究工具。常见的实验动物包括小鼠、大鼠、豚鼠、地鼠(仓鼠)、兔、犬、猴、猪和鱼等。然而，人类和动物的基因和蛋白质序列还是存在不少差异，许多人类蛋白质不能与动物的同源蛋白质结合而产生生物活性，导致许多临床试验的结果也与动物实验的结果不相符。
随着基因工程技术的不断发展和成熟，用人类细胞或基因替代或置换动物的内源性同类细胞或基因，以建立更接近人类的生物体系或疾病模型，建立人源化实验动物模型(humanized animal model)，已经为临床上新的治疗方法或手段提供了重要工具。其中基因人源化动物模型，即利用基因遗传操作技术，用人类正常或突变基因替换动物同类基因，可在动物体内建立更接近人类的正常或突变。由于人类基因片段的存在，动物体内可表达或部分表达含有人类功能的蛋白质，从而大大减少人和动物的临床实验差异，为在动物水平进行药物筛选提供了可能。
2019-nCoV与SARS冠状病毒一样都以血管紧张素转化酶2(Angiotensin-converting enzyme 2,ACE2)作为感染人类的关键靶点，其中2019-nCoV除感染人类外还可感染多种哺乳动物如猴子、猪、兔子、白鼬、猩猩等，但小鼠和大鼠除外。猴子、猪以及兔子等作为动物模型感染2019-nCoV用作药物筛选而言，其生长周期较长且体型较大难以大批量操作，而相对容易大批量操作的小鼠模型却对2019-nCoV不易感。
四倍体是指细胞中含有的染色体是最小染色体组数的四倍，即细胞中具有四个完整的染色体组的生物个体或者细胞。在自然条件下，哺乳动物四倍体胚胎的发生率极低而且普遍不能正常发育成为一个单独个体。
将一定数量的胚胎干细胞(ES)细胞和四倍体胚胎嵌合，在其嵌合体的发育过程中，ES细胞和四倍体胚胎不是随机分布的，即其四倍体胚胎部分仅参与卵黄囊内胚层和胎盘滋养层细胞(如绒毛膜外胚层、滋养层细胞等)等胚外组织的形成，而ES细胞则广泛的参与胚体、尿囊、羊膜、卵黄囊中胚层和绒毛膜中胚层部分的生成，而不参与生成卵黄囊内胚层和胎盘滋养层细胞谱系，即二者的发育潜能具有互补性，这种现象称之为四倍体互补技术。
由这项技术克隆出的动物个体，完全是由ES细胞发育而来，我们称之为ES动物。通过细胞核移植方法制备的克隆胚胎移植到代孕母体后胎儿的出生率极低，仅为1-2％，而通过四倍体补偿技术，即将ESC细胞系注射入囊胚期的四倍体胚胎载体中，可将胎儿的出生率提升至20-30％，显著提升了动物克隆的效率。近年来，国内外众多科学家都深入研究此项技术，并取得了很多创造性的研究成果。四倍体补偿技术所产生的动物模型有着非常普遍的应用，例如确定谱系特异性基因功能，分析胚外组织与胚胎组织的基因功能、识别细胞自发和非自发的基因功能、区分主要与次要缺陷、促进表型分析等。胚胎嵌合体的应用并不局限于早期胚胎发育的研究，也可应用于出生后胎儿发育，身体机能的研究。当嵌合体与分子工具结合使用时，这种分子工具可以在细胞中以时间和谱系特异性方式修饰遗传活性，为基因功能精确、深入和大规模分析提供便利。可以通过与条件性改变基因表达的方式来改变遗传活动(Nagy 2000)或调节基因功能。目前对于ES细胞的发育潜力的评价主要集中在研究细胞体外分化，以及反映细胞多能性分子标记的转录活性的分析。胚胎嵌合体的一个独特特征就是外来细胞可以嵌合入胚胎，细胞可以在胚胎发育过程中充分激发分化潜能。细胞受到全面细胞谱系的测试，这更能揭示多能性的真实程度。嵌合体是对于预测哺乳类动物多能性细胞体内评价最全面和最严格的重要工具。
发明内容
在一些实施方案中，本公开提供了一种可以提高动物出生率的制备方法。
在一些实施方案中，本公开提供了了一种动物四倍体补偿或互补方法(tetraploid embryo complementation)。
在一些实施方案中，本公开提供了一种制备动物的方法，所述方法包括将四倍体胚胎与胚胎干细胞聚合形成新的重构胚或嵌合体胚胎；所述的四倍体胚胎为处于2-细胞期的四倍体胚胎。
一些实施方案中，所述胚胎干细胞为代数为p15代以内的胚胎干细胞。
一些实施方案中，所述胚胎干细胞为代数为p12-p15代的胚胎干细胞。
一些实施方案中，所述方法使用了四倍体补偿法或四倍体胚胎互补法(tetraploid embryo complementation)。
一些实施方案中，所述方法包括以下步骤：(1)获得动物2-细胞胚胎；(2)将步骤(1)所述的2-细胞胚胎放入融合液中，进行融合，获得四倍体胚胎；(3)将步骤(2)中的四倍体胚胎放入培养基中培养；(4)将步骤(3)中发育到2-细胞期的四倍体胚胎与胚胎干细胞聚合，形成嵌合体胚胎；(5)将步骤(4)中的嵌合体胚胎植入假孕的动物子宫中，胚胎发育至足孕，从而获得动物。
一些实施方案中，步骤(3)中的培养时间为8-24小时。
一些实施方案中，步骤(3)中培养基为KSOM培养基。
一些实施方案中，源自该接纳者胚胎的非人类动物可以是除人类之外的任何动物，如猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴。同时，用作被移植入接纳者的细胞原始来源的哺乳动物，可以是人类或除人类之外的哺乳动物，例如，株、大鼠、小鼠、牛、绵羊、山羊、马、狗、狒狒、黑猩猩、大猩猩、猩猩、猴、狨猴、和倭黑猩猩等。
一些实施方案中，所述动物为哺乳动物。
一些实施方案中，所述动物为非人类哺乳动物。
一些实施方案中，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴。
一些实施方案中，所述动物选自鼠。一些实施方案中，所述动物选自成鼠。一些实施方案中，所述动物选自胎鼠。
现有技术表明，目前制备动物的技术难以满足实际应用的要求。例如，对于小鼠的制备中，早期研究发现小鼠四倍体胚胎不能正常发育，只能形成胎盘的滋养层和胚外内胚层(Tarkowski et al.,1977)，而胚胎干细胞可以形成整个胎儿本身，以及卵黄囊的中胚层，羊膜，尿囊，脐带等，但滋养层和卵黄囊内胚层的形成能力十分有限(Beddington et al.,1989)。四倍体补偿技术就是基于这种完美的互补关系而产生出来的，在最极端的情况下，使用最好质量的纯系遗传背景的胚胎干细胞，胎儿出生率最高可以达到15％，但这些小鼠在出生后不久全部死亡(Nagy et al.,1990)。
后来人们发现使用早期传代的F1遗传背景的胚胎干细胞得到的嵌合体胚胎可以足月发育并活到成年，但效率只有3.8％(Nagy et al.,1993)。后来有报道，基因打靶后的F1胚胎干细胞经过再克隆后存活率可以达到5-15％，但纯系胚胎干细胞制造小鼠的存活率仍然只有0-1.4％(Eggan et al.,2001)。2006年Guy S Eakin et al.发表了利用胚胎干细胞与二倍体或四倍体聚集产生小鼠的方法(Eakin and Hadjantonakis,2006)。以及其他方法文献(Gertsenstein,2015；Kang and Gao,2015；Li et al.,2015；Shinozawa et al.,2006；Tanaka et al.,2009；Wen et al.,2014；Yamaguchi et al.,2018；Zhao et al.,2009；Zhao et al.,2010)。2009年Michal J.Boland et al.利用四倍体补偿技术从小鼠诱导多能性干细胞中产生小鼠出生率在0-7％，大多为0％(Boland et al.,2009)，其中周琪在国际期刊NATURE上发表的出生率也仅在0-3％之间(Zhao et al.,2009)。尽管F1背景的胚胎干细胞通过大量细胞株筛选，技术改进，以及再克隆，通过四倍体补偿技术产生小鼠的效率得到提高，但F1不是理想的遗传背景，该技术也仍难以满足实际应用的要求，尤其是用纯系胚胎干细胞通过四倍体补偿技术直接生产转基因鼠仍然面临很大的困难。
一些实施方案中，本公开提供了制备基因编辑动物的方法，使用了所述动物的制备方法。一些实施方案中，所述动物为基因人源化动物。一些实施方案中，所述动物为哺乳动物。一些实施方案中，所述动物为非人类哺乳动物。一些实施方案中，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴。一些实施方案中，所述啮齿类动物为鼠。一些实施方案中，所述动物为成鼠。一些实施方案中，所述动物为胎鼠。
基因编辑小鼠的获得通常有以下几种：多能干细胞的囊胚注射；受精卵注射直接编辑；体细胞核移植；四倍体补偿技术等。其中多能干细胞囊胚注射需要获得生殖系传递的嵌合体小鼠再进行隔代繁殖获得纯合子小鼠，历时需要5个月以上；受精卵注射一般用于基因敲除编辑，基因编辑策略受限且技术操作难度大，后续还需对出生小鼠进行鉴定不一定能直接获得目标小鼠；体细胞核移植与四倍体补偿技术皆能直接获得纯合子基因编辑小鼠，但两种方法存活率都很低，在10％以下，一般在1％左右。而且体细胞核移操作难度大，显微注射对胚胎造成伤害较大，四倍体补偿法不会对胚胎造成直接伤害。对于直接获得基因编辑小鼠而言，四倍体补偿技术相对于体细胞核移植操作简便，效率高，获得基因编辑动物时间短，且在多能干细胞上进行基因编辑相对容易。
一些实施方案中，提供了一种基因小鼠的制备方法，所述方法包括以下步骤：(1)获得小鼠2-细胞胚胎；(2)将步骤(1)所述的2-细胞胚胎放入融合液中，进行融合，获得四倍体胚胎；(3)将步骤(2)中的四倍体胚胎放入培养基中培养；(4)将步骤(3)中发育到2-细胞期的四倍体胚胎与胚胎干细胞聚合，形成嵌合体胚胎；(5)将步骤(4)中的嵌合体胚胎植入假孕的小鼠子宫中，胚胎发育至足孕，从而获得基因编辑小鼠。
一些实施方案中，所述方法包括将将胚胎干细胞和四倍体胚胎聚合形成新的重构胚。其中，所述的胚胎干细胞可以为普通的胚胎干细胞，也可以为基因编辑的胚胎干细胞，例如人源化基因的动物胚胎干细胞等，具体不限。
一些实施方案中，提供了一种动物嵌合体胚胎的制备方法，所述方法包括将四倍体胚胎与胚胎干细胞聚合形成新的重构胚或嵌合体胚胎； 所述的四倍体胚胎为处于2-细胞期的四倍体胚胎。
一些实施方案中，所述方法使用了四倍体补偿法或四倍体胚胎互补法。
一些实施方案中，所述方法包括以下步骤：(1)获得动物2-细胞胚胎；(2)将步骤(1)所述的2-细胞胚胎放入融合液中，进行融合，获得四倍体胚胎；(3)将步骤(2)中的四倍体胚胎放入培养基中培养；(4)将步骤(3)中发育到2-细胞期的四倍体胚胎与胚胎干细胞聚合，形成嵌合体胚胎。一些实施方案中，步骤(3)中的培养时间为8-24小时。一些实施方案中，步骤(3)中培养基为KSOM培养基。一些实施方案中，所述动物为哺乳动物。一些实施方案中，所述动物为非人类哺乳动物。一些实施方案中，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴。一些实施方案中，所述动物选自鼠。一些实施方案中，所述动物选自成鼠。一些实施方案中，所述动物选自胎鼠。
一些实施方案中，所述方法包括将发育到2-细胞期的四倍体胚胎与胚胎干细胞聚合得到嵌合体胚胎。发明人又意外地发现，利用2-细胞期的四倍体胚胎与胚胎干细胞聚合，极大的改善了四倍体补偿技术制作小鼠的效率稳定性差，对来自纯系小鼠的胚胎干细胞效率低下的问题，小鼠出生率有了质的提升，接近正常胚胎移植，同时也克服了目前最先进基因编辑方法Cas9的局限性，可以从干细胞直接制造出胚胎和成年鼠进行表型研究，节省老鼠繁殖需要的大量的时间，人力和物力，彻底解决了四倍体补偿技术用来制作转基因小鼠的实用性问题，达到了商业化的水平。
一些实施方案中，制备动物的方法中，使用了一种组合物，成分包括甘露醇、MgSO 4、CaCl 2和牛血清白蛋白；所述甘露醇、MgSO 4、CaCl 2和牛血清白蛋白的质量比为9～53：0.015～0.241：0.013～0.23：0.01～5。
一些实施方案中，所述方法使用了一种组合物，所述组合物成分包括甘露醇、MgSO 4、CaCl 2和牛血清白蛋白；所述甘露醇、MgSO 4、CaCl 2和牛血清白蛋白的质量比为9～53：0.015～0.241：0.013～0.23：0.01～5。
一些实施方案中，所述组合物中甘露醇、MgSO 4、CaCl 2和牛血清白蛋白的质量比为18～52：0.018～0.241：0.016～0.23：0.01-4。
一些实施方案中，所述组合物中甘露醇、MgSO 4、CaCl 2和牛血清白蛋白的质量比为27～52：0.018～0.12：0.016～0.1：1～3.5。
一些实施方案中，所述组合物包括以下成分：甘露醇0.05-0.29M、MgSO 40.12-2mM、CaCl 20.12-2mM、牛血清白蛋白0.01-5mg/mL。
一些实施方案中，所述组合物包括以下成分：甘露醇0.1-0.28M、MgSO 40.15-2mM、CaCl 20.15-2mM、牛血清白蛋白0.01-4mg/mL。
一些实施方案中，所述组合物包括以下成分：甘露醇0.15-0.28M、MgSO 40.15-1mM、CaCl 20.15-1mM、牛血清白蛋白1-3.5mg/mL。
一些实施方案中，所述组合物包括以下成分：甘露醇0.18-0.28M、MgSO 40.15-0.5mM、CaCl 20.15-0.5mM、牛血清白蛋白2-3.5mg/mL。
一些实施方案中，所述组合物包括以下成分：甘露醇0.2-0.28M、MgSO 40.15-0.3mM、CaCl 20.15-0.3mM、牛血清白蛋白2-3mg/mL。
一些实施方案中，所述组合物包括以下成分：甘露醇0.27M、MgSO 40.2mM、CaCl 20.2mM、牛血清白蛋白3mg/mL。
一些实施方案中，所述组合物可以作为母液，然后配制成所需浓度的工作液。
一些实施方案中，所述组合物可以是工作液，可以无需配制，直接使用。
一些实施方案中，本公开提供了所述组合物在制备基因编辑动物胚胎细胞或基因编辑动物中的应用。
一些实施方案中，所述组合物用于制备动物四倍体胚胎。
一些实施方案中，所述方法使用了一种融合液，所述融合液含有甘露醇、牛血清白蛋、Mg 2+和Ca 2+，所述融合液具有提高了浓度的Mg 2+和Ca 2+；或者，所述融合液Mg 2+和Ca 2+的浓度分别为0.12-2mM、0.12-2mM。
一些实施方案中，所述的融合液体中的甘露醇、牛血清白蛋的浓度分别为0.05-0.29M、0.01-5mg/mL。
一些实施方案中，所述的Mg 2+和Ca 2+分别来源于MgSO 4和CaCl 2。
一些实施方案中，所述融合液用于制备四倍体胚胎。
目前，四倍体的获得方法有生物法、化学法和物理法制备。通过显微操作将两个二倍体胚胎细胞核注射到1个1-细胞期胚胎细胞细胞质中对操作技术要求高，同时显微操作对胚胎损害较大；使用细胞松弛素B或秋水仙素抑制卵裂球细胞的分裂制备四倍体会对胚胎发育造成不良影响，甚至延迟阻滞胚胎发育；另外还可采用仙台病毒、聚乙二醇、直流电击等方法来进行细胞融合，仙台病毒存在致病性，聚乙二醇残存毒性，而电融合方法仅在短时间内发生可逆转的电穿孔，克服了化学试剂的毒害和病毒的致病性，是制作四倍体胚胎最常用和最高效的方法。但是现有的四倍体补偿技术还存在胚胎电融合效率达不到100％，制作小鼠的效率稳定性差，对来自纯系小鼠的胚胎干细胞效率低下的问题。而发明人在研究过程中，意外地发现使用本公开的改进的电融合液的融合效率可从80-90％提高到100％，具有极大地现实意义。
一些实施方案中，本公开提供了所述的方法制备得到的动物。
一些实施方案中，所述动物为哺乳动物。一些实施方案中，所述动物为非人类哺乳动物。一些实施方案中，所述动物选自猪、大鼠、小 鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴。一些实施方案中，所述动物选自鼠。一些实施方案中，所述动物选自成鼠。一些实施方案中，所述动物选自胎鼠。一些实施方案中，所述动物选自基因编辑动物。一些实施方案中，所述动物选自基因人源化动物。一些实施方案中，所述基因为ACE2。
一些实施方案中，本公开提供了一种融合液，含有甘露醇、牛血清白蛋、Mg 2+和Ca 2+，所述融合液具有提高了浓度的Mg 2+和Ca 2+；或者，所述融合液Mg 2+和Ca 2+的浓度分别为0.12-2mM、0.12-2mM。
一些实施方案中，所述的融合液体中的甘露醇、牛血清白蛋的浓度分别为0.05-0.29M、0.01-5mg/mL。
一些实施方案中，所述的Mg 2+和Ca 2+分别来源于MgSO 4和CaCl 2。
一些实施方案中，所述制备动物的方法使用了所述的融合液。
一些实施方案中，本公开提供了一种基因编辑动物或其子孙的组织、体液、细胞、细胞核以及它们的破碎物或提取物，所述的动物是利用上述方法构建的。一些实施方案中，所述动物为哺乳动物。一些实施方案中，所述动物为非人类哺乳动物。一些实施方案中，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴。一些实施方案中，所述动物选自鼠。一些实施方案中，所述动物选自成鼠。一些实施方案中，所述动物选自胎鼠。
由于人源ACE2和鼠源ACE2在基因序列上存在一定差异，有文献报道：病毒感染后，人源ACE2较鼠源ACE2对SARS-CoV的敏感性更强，病理症状更为明显。目前的临床研究急需更好的动物模型。
已有hACE2转基因小鼠被证实可感染2019-nCoV并出现肺部组织典型致病特征(https://www.biorxiv.org/content/10.1101/2020.02.07.939389v3#disqus_thread)。但hACE2转基因小鼠为全身性过表达hACE2小鼠模型，并不能模拟ACE2时空组织表达特征。
在一些实施方案中，本公开将通过在小鼠ACE2位点表达人源化ACE2的方法大批量制备2019-nCoV易感小鼠人源化ACE2动物模型来对2019-nCoV进行药物筛选和疾病研究等应用。
在一些实施方案中，本公开提供了一种特异性的RNA片段序列。
在一些实施方案中，所述的RNA片段序列为分离的RNA片段序列。
在一些实施方案中，本公开提供了一种特异性的靶向ACE2基因的sgRNA序列。
在一些实施方案中，所述的sgRNA序列为分离的sgRNA序列。在一些实施方案中，本公开提供了一种特异性的靶向ACE2基因的靶向载体。
在一些实施方案中，所述的靶向载体为分离的靶向载体。
在一些实施方案中，本公开提供了一种ACE2基因人源化细胞株。
在一些实施方案中，本公开提供了一种ACE2基因人源化细胞株的制备方法。
在一些实施方案中，本公开提供了一种ACE2基因人源化动物。
在一些实施方案中，本公开提供了一种基因人源化动物的制备方法。
在一些实施方案中，本公开提供了一种ACE2基因人源化的小鼠胚胎干细胞模型。
在一些实施方案中，本公开提供了一种引物组合，所述引物组合包括与如SEQ ID NO:19所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:20所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物。
在一些实施方案中，上述引物为分离的引物。
在一些实施方案中，所述引物组合还包括与如SEQ ID NO:21所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:22所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物。
在一些实施方案中，上述引物为分离的引物。
在一些实施方案中，所述引物组合还包括与如如SEQ ID NO:23所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:24所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物。
在一些实施方案中，上述引物为分离的引物。
在一些实施方案中，所述引物组合还包含与如SEQ ID NO:25所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:26所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物。
在一些实施方案中，上述引物为分离的引物。
在一些实施方案中，本公开提供了所述引物组合在制备细胞株或细胞系或非人动物中的应用。
在一些实施方案中，上述细胞为为分离的细胞。
在一些实施方案中，所述动物为哺乳动物。在一些实施方案中，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩或猴。在一些实施方案中，所述哺乳动物为啮齿类动物。在一些实施方案中，所述动物为鼠。在一些实施方案中，所述动物选自成鼠。在一些实施方案中，所述动物选自胎鼠。
在一些实施方案中，所述动物为基因人源化动物。
在一些实施方案中，所述基因为ACE2。
在一些实施方案中，本公开提供了所述引物组合在制备打靶载体中的应用。
在一些实施方案中，本公开提供了一种打靶载体，包含5’同源臂序列、人源ACE2基因片段和SV40 polyA序列连接在一起；所述5’同源臂为与在所述目标基因组基因座处的5’靶序列同源的5’同源臂。
在一些实施方案中，上述打靶载体为分离的打靶载体。
在一些实施方案中，所述打靶载体通过使用所述的引物组合连接5’同源臂序列、人源ACE2基因片段和SV40 polyA序列。
在一些实施方案中，所述打靶载体用于将人源ACE2基因的CDS序列插入到动物基因的启动子和5’UTR区域序列后，利用动物目的基因启动子启动人目的基因表达。
在一些实施方案中，所述5’同源臂序列与如SEQ ID NO:15所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性。
在一些实施方案中，所述ACE2基因的CDS序列与如SEQ ID NO:12所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性。
在一些实施方案中，所述SV40 polyA序列与如SEQ ID NO:14所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性。
在一些实施方案中，所述SV40 polyA序列位于所述的CDS序列之后。
在一些实施方案中，所述打靶载体还包含3’同源臂，所述3’同源臂为与在所述目标基因组基因座处的3’靶序列同源的3’同源臂。
在一些实施方案中，所述打靶载体还包含与如SEQ ID NO:17所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的筛选标志PGK-Puro。
在一些实施方案中，所述打靶载体还包含与如SEQ ID NO:18所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的Frt序列。
在一些实施方案中，所述打靶载体各个序列片段的连接顺序依次为5’同源臂序列、人源ACE2基因片段、SV40 polyA序列、frt序列、PGK-Puro序列、frt序列和3’同源臂序列。
在一些实施方案中，所述动物为哺乳动物。在一些实施方案中，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴。在一些实施方案中，所述哺乳动物为啮齿类动物。在一些实施方案中，所述动物为鼠。在一些实施方案中，所述动物选自成鼠。在一些实施方案中，所述动物选自胎鼠。
在一些实施方案中，所述动物为基因人源化动物。
在一些实施方案中，所述基因为ACE2。
在一些实施方案中，本公开提供了所述的打靶载体在制备基因人源化动物模型中的应用。所述的人源化ACE2小鼠模型为原小鼠ACE2位点特异性表达hACE2小鼠模型，可模拟原mACE2表达特征，具有组织特异性，更为严谨的模拟人感染2019-nCoV发病过程。
在一些实施方案中，所述动物为哺乳动物。在一些实施方案中，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴。在一些实施方案中，所述哺乳动物为啮齿类动物。在一些实施方案中，所述动物为鼠。在一些实施方案中，所述 动物选自成鼠。在一些实施方案中，所述动物选自胎鼠。
在一些实施方案中，所述动物为基因人源化动物。
在一些实施方案中，所述基因为ACE2。
在一些实施方案中，本公开提供了一种制备所述打靶载体的方法，包括以下步骤：将PCR扩增得到的产物片段5’同源臂、人ACE2 CDS和SV40 polyA使用搭桥PCR法PCR成连续片段5arm-hACE-SV40。
在一些实施方案中，所述PCR反应体系为：2×Phanta Max Buffer约为25μL；dNTP Mix约为1μL；10μM上游引物约为2μL；10μM下游引物约为2μL；DNA Polymerase约为1μL；模板链5’同源臂、人ACE2 CDS、SV40 polyA片段各约为20-200ng；H 2O补充至50μL；PCR扩增反应条件约为62-68℃起始，每个循环降约为0.2-0.5℃。
在一些实施方案中，扩增所述5’同源臂片段使用的引物包括与如SEQ ID NO:19所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:20所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物。
在一些实施方案中，所述引物为分离的引物。
在一些实施方案中，扩增所述人源ACE2基因片段使用的引物包括与如SEQ ID NO:21所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:22所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物。
在一些实施方案中，所述引物为分离的引物。
在一些实施方案中，所述SV40 polyA序列使用的引物包括与如SEQ ID NO:23所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:24所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物。
在一些实施方案中，所述引物为分离的引物。
在一些实施方案中，所述方法还包括以下步骤：将5arm-hACE-SV40片段进行AgeI+MluI双酶切；3’同源臂片段进行AscI+HindIII双酶切后分别通过酶切连接的方法连接上去，从而得打靶载体。
在一些实施方案中，所述3’同源臂片段使用的引物包括与如SEQ ID NO:25所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:26所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物。
在一些实施方案中，所述引物为分离的引物。
在一些实施方案中，本公开提供了一种人源化动物细胞株的制备方法，所述方法中使用了所述的引物组合。
在一些实施方案中，所述的方法包括使用了所述的打靶载体。
在一些实施方案中，所述方法包括将人源目的基因导入动物细胞中，使得目的基因在动物细胞内表达人源目的基因的CDS。
在一些实施方案中，所述目的基因为ACE2。
在一些实施方案中，所述动物为哺乳动物。在一些实施方案中，所述动物为啮齿类动物。在一些实施方案中，所述动物为鼠。
在一些实施方案中，所述细胞为胚胎干细胞。
在一些实施方案中，所述制备方法包括以下步骤：(1)制备所述的打靶载体；(2)将制备的打靶载体和连接有sgRNA的载体导入动物来源的胚胎干细胞中；(3)将步骤(2)中的胚胎干细胞培养成克隆，即得。
在一些实施方案中，所述sgRNA包括与如SEQ ID NO：1或SEQ ID NO：2所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的sgRNA。
在一些实施方案中，所述动物为哺乳动物。在一些实施方案中，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴。在一些实施方案中，所述哺乳动物为啮齿类动物。在一些实施方案中，所述啮齿类动物为鼠。在一些实施方案 中，所述动物选自成鼠。在一些实施方案中，所述动物选自胎鼠。在一些实施方案中，所述动物为基因人源化动物。
在一些实施方案中，所述基因为ACE2。
在一些实施方案中，本公开提供了所述的方法制备得到的ACE2基因人源化动物细胞株或细胞系。
在一些实施方案中，所述细胞为人源化小鼠胚胎干细胞。
在一些实施方案中，本公开提供了一种非人动物的制备方法，包括引用了上述引物组合。
在一些实施方案中，所述制备方法使用了所述的打靶载体。
在一些实施方案中，包括将所述的细胞注入动物体内。
在一些实施方案中，所述动物为哺乳动物。在一些实施方案中，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴。在一些实施方案中，所述哺乳动物为啮齿类动物。在一些实施方案中，所述啮齿类动物为鼠。在一些实施方案中，所述动物选自成鼠。在一些实施方案中，所述动物选自胎鼠。在一些实施方案中，所述动物为基因人源化动物。
在一些实施方案中，所述基因为ACE2。
在一些实施方案中，本公开提供了一种非人动物，由上述方法制备得到的。
在一些实施方案中，所述动物为哺乳动物。在一些实施方案中，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴。在一些实施方案中，所述哺乳动物为啮齿类动物。在一些实施方案中，所述啮齿类动物为鼠。在一些实施方案中，所述动物选自成鼠。在一些实施方案中，所述动物选自胎鼠。在一些实施方案中，所述动物为基因人源化动物。
在一些实施方案中，所述基因为ACE2。
在一些实施方案中，所述人源化小鼠胚胎干细胞中包括人ACE2基因，该人源化小鼠胚胎干细胞经特定分化或制备成小鼠模型后可表达人的全长ACE2蛋白，同时内源ACE2蛋白表达降低或消失。
在一些实施方案中，本公开提供了一种人源化鼠或其子孙的组织、体液、细胞、以及它们的破碎物或提取物，所述的人源化鼠是上述的方法制备的。
在一些实施方案中，本公开提供了来源于所述的制备方法得到的人源化动物模型或其后代在制造人类抗体，或者作为药理学、免疫学、微生物学和医学研究的模型系统中的应用，或在生产和利用动物实验疾病模型，用于病原学研究和/或用于开发新的诊断策略和/或治疗策略中的应用，或在筛选、验证、评价或研究ACE2基因功能、ACE2抗体、针对ACE2靶点的药物、药效研究方面的用途。
附图说明
图1为pX330质粒图谱。图2为pX330-sgRNA1构建测序结果图。图3为pX330-sgRNA2构建测序结果图。图4为pX330-sgRNA1-3切割效率验证结果。图5为pX330-sgRNA3构建测序结果图。图6为人源化ACE2打靶策略示意图。图7为人源化ACE2打靶载体测序结果信息。图8为对比例1中的三片段连接的PCR鉴定图。图9为人源化ACE2小鼠胚胎干细胞基因型的PCR鉴定结果图。图10为删除PGK-Puro后人源化ACE2小鼠胚胎干细胞基因型的PCR鉴定结果图。图11为人源化ACE2基因示意图。图12为例8形成的人源化ACE2基因改造小鼠图片。图13为qPCR检测人源化ACE2小鼠hACE2的表达，结果显示人源化ACE2小鼠组织特异表达hACE2，而野生型小鼠不表达hACE2。图14为qPCR检测人源化ACE2小鼠mACE2的表达，结果显示hACE2小鼠其mACE2表达缺失。图15为以免疫印迹实验检测hACE2小鼠以及野生型ACE2小鼠的肠组织中的hACE2蛋白的表达，结果显示hACE2小鼠在蛋白水平上表达hACE2蛋白。图16为例10、试验例1、例11、试验例2制备小鼠的流程图。图17为例12、试验例3、例13、试验例4制备小鼠的流程图。图18为显示例10-13小鼠出生率的结果图。图19为显示试验例1-4小鼠出生率的结果图。
具体实施方式
以下通过具体的实施例进一步说明本公开的技术方案，具体实施例不代表对本公开保护范围的限制。其他人根据本公开理念所做出的一些非本质的修改和调整仍属于本发明的保护范围。
除非另有定义,本文中所使用的所有技术与科学术语的定义与本领域技术人员所熟悉的定义相同。此外,任何与所记载内容相似或均等的方法和材料皆可应用于本公开方法中,具体实施方式中描述了优选的方法和材料。
文中所用的“一”和“一种”指语法上不定冠词的释义,表示“一个”、“一种”或“多个”、“多种"(即“至少一个”、“至少一种”)。例如“一要素”指一种或种要素。
“CDS”是编码序列(Coding sequence)的缩写，“编码序列”是指用于编码基因的多肽产物的任何核苷酸序列。相反，术语“非编码序列”是指不编码基因的多肽产物的任何核苷酸序列。
术语“片段”将被理解为指长度比参考核酸短并且在共同部分包含与参考核酸相同的核苷酸序列的核苷酸序列。如果合适的话，根据本公开的这样的核酸片段可以被包含在更大的多核苷酸中，该片段是该更大的多核苷酸的组成成分。这样的片段包括长度在本公开的核酸的至少6、8、9、10、12、15、18、20、21、22、23、24、25、30、39、40、42、45、48、50、51、54、57、60、63、66、70、75、78、80、90、100、105、120、135、150、200、300、500、720、900、1000或1500个连续核苷酸范围内的寡核苷酸，或可选地由这样的寡核苷酸组成。
在本说明中,除非上下文另有要求，词语"包含"、"包括"将被理解为是指包括所述的步骤或要素或步骤和要素的集合,但并不排除任何其它的步骤或要素或步骤和要素的集合；即开放式限定。
“相对应”是指:(a)一多核苷酸具有与参考核苷酸序列的全部或者部分基本上相同或互补的核苷酸序列,或者一多核苷酸编码与肽或者蛋白质中的氨基酸序列完全相同的氨基酸序列；或(b)一肽或多肽具有一种氨基酸序列,该氨基酸序列基本上与参考肽或蛋白质中的氨基酸序列相同。
术语“下游”是指位于参考核苷酸序列3’端的核苷酸序列。特别地，下游核苷酸序列通常涉及转录起始点之后的序列。例如，基因的翻译起始密码子位于转录起始位点的下游。
术语“上游”是指位于参考核苷酸序列5’端的核苷酸序列。特别地，上游核苷酸通常涉及位于编码序列或转录起始点的5’侧的序列。例如，大部分的启动子位于转录起始位点的上游。
“启动子”是指能够控制编码序列或功能性RNA的表达的DNA序列。一般而言，编码序列位于启动子序列的3’端。启动子可以整体源自天然基因，或由源自天然发现的不同启动子的不同元件组成，或甚至包括合成的DNA片段。本领域技术人员应该理解的是，不同的启动子可以指导基因在不同的组织或细胞类型中，或在发育的不同阶段，或应答于不同的环境或生理条件进行表达。导致基因在大多数细胞类型中在大多数的时间被表达的启动子通常称为“组成型启动子”。导致基因在特定的细胞类型中被表达的启动子通常称为“细胞特异性启动子”或“组织特异性启动子”。导致基因在特定的发育或细胞分化阶段被表达的启动子通常称为“发育特异性启动子”或“细胞分化特异性启动子”。在将细胞暴露于诱导启动子的药剂、生物分子、化学品、配体、光或类似物，或用这些物质对细胞进行处理之后，被诱导并导致基因被表达的启动子通常被称为“诱导型启动子”或“调控型启动子”。还应该认识的是，因为在大多数情况下，调控序列的准确界限还没有完全限定，所以不同长度的DNA片段可能具有相同的启动子活性。
术语“5’UTR”或“5'非编码序列”或“5'非翻译区(UTR)”是指位于编码序列上游(5')的DNA序列。
术语“限制性核酸内切酶”和“限制性酶”是指结合并切割双链DNA内的特定核苷酸序列的酶。
术语“载体”意指核酸分子，其能转移它已连接的核酸分子。一种载体类型是“质粒”，其指环状双链DNA环，其他DNA区段可连接进去。另一类载体是病毒载体，其中其他DNA区段可连接到病毒基因组内。某些载体能在引入了这些载体的宿主细胞中自我复制(如具有细菌的复制起始点的细菌载体以及游离型哺乳动物载体)。其他载体(如非游离型哺乳动物载体)在引入到宿主细胞中后能够整合到宿主细胞的基因组中，因此随宿主基因组复制。此外，某些载体能够指导表达它们操作地连接的基因。
一些载体本公开称为“重组表达载体”(或简称为“表达载体”)是指被设计成使得插入的核酸序列在转化入宿主后能够表达的载体、质粒或媒介。总的来说，重组DNA技术所使用的表达载体经常是质粒形式。本说明书的“质粒”和“载体”交换使用，因为质粒是载体最普遍使用的形式。但是，本公开意包括这种表达载体的其他形式，如病毒载体(如复制缺陷型反转录病毒、腺病毒和腺伴随病毒)，其充当同等作用。
术语“质粒”是指染色体外元件，它们常常携带不是作为细胞的中心代谢的一部分的基因，并且常常是环状双链DNA分子的形式。这样的元件可以是来自任何来源的自主复制序列、基因组整合序列、噬菌体或核苷酸序列，线性、环状或超螺旋的，单链或双链DNA或RNA，其中许多核苷酸序列已经被连接入或重组入独特的结构中，该结构能够将针对所选的基因产物的启动子片段和DNA序列以及合适的3’端非翻译序列导入细胞。
“靶向载体”或“打靶载体”是含有邻接所需遗传修饰的、与内源染色体核酸序列“同源的”序列的DNA构建体。所述侧翼同源序列(称为“同源臂”)借助所述同源臂和相应的内源序列之间存在的同源性，指导所述打靶载体定位于所述基因组中的特定染色体位置，并且通过称为“同源重组”的过程引入所述所需的遗传修饰。“靶向载体”和“打靶载体”某些时候可以通用。采用靶向载体以将插入核酸引入大鼠、真核、非大鼠真核、哺乳动物、非人类哺乳动物、人类、啮齿动物、非大鼠啮齿动物、小鼠或仓鼠核酸的靶基因座中。所述靶向载体包含所述插入核酸且进一步包含5’同源臂和3’同源臂，其侧接所述插入核酸。侧接所述插入核酸的同源臂对应于在大鼠、真核、非大鼠真核、哺乳动物、非人类哺乳动物、人类、啮齿动物、非大鼠啮齿动物、小鼠或仓鼠核酸的靶基因座内的区域。为了便于提及，在靶基因组基因座内的相应同源基因组区在本文中称为“靶位点”。例如，靶向载体可包含由与第一靶位点和第二靶位点互补的第一同源臂和第二同源臂侧接的第一插入核酸。因而，所述靶向载 体由此有助于经由在细胞的基因组内的同源臂和互补靶位点之间发生的同源重组事件将插入核酸整合到大鼠、真核、非大鼠真核、哺乳动物、非人类哺乳动物、人类、啮齿动物、非大鼠啮动物、小鼠或仓鼠核酸的靶基因座中。
在一个实施方案中，所述大鼠、真核、非大鼠真核、哺乳动物、非人类哺乳动物、人类、啮齿动物、非大鼠啮齿动物、小鼠或仓鼠核酸的靶基因座包含与5’同源臂互补的第一核酸序列和与3’同源臂互补的第二核酸序列。
载体可以通过本领域已知的方法导入期望的宿主细胞，例如转染、电穿孔、微注射、转导、细胞融合、DEAE葡聚糖、磷酸钙沉淀、脂转染(溶酶体融合)、使用基因枪或DNA载体转运蛋白(参见例如Wu et al.,1992,J.Biol.Chem.267:963-967；Wu和Wu,1988,J.Biol.Chem.263:14621-14624；和Hartmut et al.,1990年3月15日提交的加拿大专利申请2,012,311)。
术语“转染”是指细胞摄取外源或异源RNA或DNA。当外源或异源RNA或DNA已被引入细胞内时，该细胞便被这样的RNA或DNA“转染”。当转染的RNA或DNA影响表型变化时，该细胞便被外源或异源RNA或DNA“转化”。转化RNA或DNA可以被整合入(共价连接入)构成细胞基因组的染色体DNA。
术语“同源性”或“同源的”指序列例如核苷酸或氨基酸序列的两条序列经最佳比对和比较具有至少约75％的核苷酸或氨基酸、至少约80％的核苷酸或氨基酸、至少约90-95％的核苷酸或氨基酸，例如超过97％的核苷酸或氨基酸是相同的。本领域技术人员将理解，对于最佳基因靶向而言，靶向构建体应含有与内源性DNA序列同源的臂(即“同源臂”)；因此，能够在靶向构建体与被靶向的内源性序列之间发生同源重组。
如本文中所用，在两个区彼此共有足够水平的序列同一性时同源臂和靶位点(即同源基因组区)彼此互补，从而充当用于同源重组反应的底物。“同源性”是指DNA序列与相应或“互补”序列相同或共有序列同一性。在给定靶位点和在靶向载体上发现的相应同源臂之间的序列同一性可为允许同源重组发生的任何程度的序列同一性。例如，靶向载体的同源臂(或其片段)与靶位点(或其片段)共有的序列同一性的量可为至少51％、53％、57％、60％、65％、70％、75％、80％、83％、85％、87％、89％、91％、93％、95％、97％、98％、99％或100％序列同一性，因此所述序列经历同源重组。此外，在同源臂和互补靶位点之间同源的互补区可具有足以促进在裂解的识别位点处同源重组的任何长度。因此同源臂与在细胞的基因组内的相应靶位点具有足以进行同源重组的同源性。为了便于提及，同源臂在本文中作为5’同源臂和3’同源臂提到。该术语涉及在靶向载体中同源臂与插入核酸的相对位置。
一些实施方案中，所述靶向载体的同源臂可具有足以促进与相应靶位点的同源重组事件的任何长度，包括例如至少5-10kb、5-15kb、10-20kb、20-30kb、30-40kb、40-50kb、50-60kb、60-70kb、70-80kb、80-90kb、90-100kb、100-110kb、110-120kb、120-130kb、130-140kb、140-150kb、150-160kb、160-170kb、170-180kb、180-190kb、190-200kb长或更长。如下文进一步详细概述，靶向载体可采用更大长度的靶向臂。在一个特定的实施方案中5’同源臂和3’同源臂的总和为至少10kb或5’同源臂和3’同源臂的总和为至少约16kb-约100kb或约30kb-约100kb，在其它实施方案中，所述ACE2的5’同源臂和3’同源臂的总和的尺寸为约10kb-约150kb、约10kb-约100kb、约10kb-约75kb、约20kb-约150kb、约20kb-约100kb、约20kb-约75kb、约30kb-约150kb、约30kb-约100kb、约30kb-约75kb、约40kb-约150kb、约40kb-约100kb、约40kb-约75kb、约50kb-约150kb、约50kb-约100kb、或约50kb-约75kb、约10kb-约30kb、约20kb-约40kb、约40kb-约60kb、约60kb-约80kb、约80kb-约100kb、约100kb-约120kb或约120kb-约150kb。
本文中的某些实施例涉及人源化基因编辑哺乳动物，所述人源化基因编辑哺乳动物的基因组包括编码人的全长ACE2蛋白的多聚核糖核酸。例如，所述多聚核糖核酸可操作地连接至启动子多聚核糖核酸。在一些实施方案中，人源化基因编辑哺乳动物不表达全部的或部分的编码人源化基因编辑哺乳动物的内源性ACE2蛋白的多聚核糖核酸，并且所述编码人ACE2蛋白的多聚核糖核酸包括人ACE2蛋白基因的修饰。
一些实施方案中，所述细胞为多潜能细胞、非多潜能细胞、哺乳动物细胞、人类细胞、非人类哺乳动物细胞、啮齿动物细胞、小鼠细胞、仓鼠细胞、非人类多潜能细胞、人类多潜能细胞、啮齿动物多潜能细胞或成纤维细胞或肺细胞。
在一些上述方法中，所述细胞为原代细胞或永生化细胞。在一些上述方法中,所述啮齿动物多潜能细胞为小鼠或大鼠胚胎干(ES)细胞。
在一些上述方法中，所述动物细胞或所述人类细胞为原代细胞或永生化细胞。在一些上述方法中，所述动物细胞或所述人类细胞为多潜能细胞。在一些上述方法中，所述动物多潜能细胞为小鼠胚胎干(ES)细胞。在一些上述方法中，所述人类多潜能细胞为人类胚胎干(ES)细胞、人类成人干细胞、发育受限的人类祖细胞或人类诱导的多潜能干(iPS)细胞。
一些实施方案中，本文中的某些实施例提供人源化基因编辑的细胞，尤其是还提供分离的人类和非人类全能或多潜能干细胞，尤其是小鼠胚胎干细胞，其能够在一种或多种体外连续基因修饰之后维持多潜能性且能够经由种系将所述靶向基因修饰传递到后代。
本文使用的术语“胚胎干细胞”或"ES细胞”包括在引入胚胎中后能够促进发育胚胎的任何组织的源自胚胎的全能或多潜能细胞。本文使用的术语“多潜能细胞”包括具有发育成多于一种类型的分化细胞的能力的未分化细胞。术语“非多潜能细胞”包括不是多潜能细胞的细胞。
在一些上述方法中，所述靶向基因编辑同时包括在所述目标基因组基因座处缺失内源核酸序列或在所述目标基因组基因座处插入所述核 酸。
一些实施方案中，所述基因修饰或基因编辑包括对细胞(例如，真核细胞、非大鼠真核细胞、哺乳动物细胞、类细胞、非人类哺乳动物细胞、多潜能细胞、非多潜能细胞、非人类多潜能细胞、人类多潜能细胞、人类ES细胞、人类成人干细胞、发育受限的人类祖细胞、人类iPS细胞、人类细胞、啮齿动物细胞、非大鼠啮齿动物细胞、大鼠细胞、小鼠细胞、仓鼠细胞、成纤维细胞或中国仓鼠卵巢(CHO)细胞)独立地实施的两种或多种修饰。第一修饰可通过电穿孔或本领域已知的任何其他方法实现。随后，采用合适的第二核酸构建体对同一细胞基因组进行第二修饰。所述第三修饰可通过第二电穿孔或本领域已知的任何其它方法实现。在各种实施方案中，在同一细胞的第一基因修饰和第二基因修饰之后,可使用例如连续电穿孔或本领域已知的任何其它合适方法(连续地)实现第三基因修饰、第四基因修饰、第五基因修饰、第六基因修饰等连修饰(一种基因修饰跟着另一基因修饰)。
一些实施方案中，本公开是打靶载体同源重组方法进行基因的编辑，将外源核酸插入内源基因组中。
一些实施方案中，所述插入核酸包含插入同源或直系同源人类核酸序列或用其替换真核、非大鼠真核、哺乳动物、人类或非人类哺乳动物核酸序列。
一些实施方案中，所述给定插入的多核苷酸可来自任何生物体，包括例如啮齿动物、非大鼠啮齿动物、大鼠、小鼠、仓鼠、哺乳动物、非人类哺乳动物、真核生物、非大鼠真核生物、人类、农业动物或家养动物。
在特定的实施方案中，所述插入核酸可包含来自大鼠的核酸，其可包含基因组DNA的片段、CDNA、调控区或其任何部分或组合。在其它实施方案中，所述插入核酸可包括来自真核生物、非大鼠真核生物、哺乳动物、人类、非人类哺乳动物、啮齿动物、非大鼠啮齿动物、人类、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、狗、白融、灵长类动物(例如，狨猴、恒河猴)、家养哺乳动物或农业哺乳动物或任何其它目标生物体的核酸。如在本文中更详细地概述，在各种方法和组合物中采用的插入核酸可引起目标靶基因座的“人源化”。
在一些实施方案中，所述基因修饰为添加核酸序列。在一个＝些实施方案中，所述插入核酸包含在编码序列中的基因修饰。在一些实施方案中，所述基因修饰包括编码序列的缺失突变。在一些实施方案中，所述基因修饰包括两种内源编码序列的融合。在一些实施方案中，所述插入核酸包含插入同源或直系同源人类核酸序列或用其替换真核、非大鼠真核、哺乳动物、人类或非人类哺乳动物核酸序列。在一些实施方案中，所述插入核酸包含在包含相应小鼠DNA序列的内源小鼠基因编码区插入同源或直系同源人类核酸序列或用其替换小鼠DNA序列。在一些实施方案中，所述插入核酸包含在包含相应小鼠DNA序列的内源小鼠基因编码区插入同源或直系同源人类核酸序列或用其替换小鼠DNA序列。在一些实施方案中，利用打靶载体，针对小鼠ACE2位点，在紧接mACE2的EXON1 CDS起始ATG位点插入hACE2序列。
在一些实施方案中，所述靶向载体的核酸序列可包含在整合到基因组中时将生成哺乳动物、人类或非人类哺乳动物ACE2基因座的区域的基因修饰的多核苷酸，其中在ACE2基因座处的基因修饰引起ACE2活性减小、ACE2活性增加或ACE2活性调整。在一些实施方案中，产生ACE2基因被完全替换。
在一些实施方案中，所述插入核酸可包含调控元件，包括例如启动子、增强子或转录。
一些实施方案中，给定插入的多核苷酸和/或哺乳动物、人类细胞或非人类哺乳动物基因座的相应替换区可为编码区、内含子、外显子、未转译区、调控区、启动子或增强子或其任何组合。
本文提供允许将一种或多种目标多核苷酸靶向整合到靶基因座中的方法，如上概述，引入序列，由此产生的基因编辑细胞。“引入”以使得序列进入细胞内部的方式而将序列呈递到细胞中(多肽或多核苷酸)。
来自任何生物体的任何细胞都可用于本文提供的方法中。在特定的实施方案中，所述细胞来自真核生物、非大鼠真核生物、哺乳动物、非人类哺乳动物、人类、啮齿动物、非大鼠啮齿动物、大鼠、小鼠或仓鼠。在特定的实施方案中，所述细胞为真核细胞、非大鼠真核细胞、多潜能细胞、非多潜能细胞、非人类多潜能细胞、非人类哺乳动物细胞、人类多潜能细胞、人类ES细胞、人类成人干细胞、发育受限的人类祖细胞、人类诱导的多潜能细胞(iPS)细胞、哺乳动物细胞、人类细胞、成纤维细胞、啮齿动物细胞、非大鼠啮齿动物细胞、大鼠细胞、小鼠细胞、小鼠ES细胞、仓鼠细胞或CHO细胞。
在一些实施方案中，在所述方法中采用的细胞具有稳定地并入其基因座中的DNA构建体。“稳定地并入”或“稳定地引入”是指将多核苷酸引入细胞中，因此核苷酸序列整合到细胞的基因组中且能够由其子代遗传。
在一些实施方案中，向细胞中引入一种或多种多核苷酸通过电穿孔、胞浆内注射、病毒感染、腺病毒、慢病毒、反转录病毒、转染、脂质介导的转染介导，或者经由NucleofectionTM介导。
在一些实施方案中，所述表达构建体与所述被引入的核酸一起引入。
在一些实施方案中，向所述细胞中引入所述一种或多种多核苷酸可经一段时间执行多次。在一些实施方案中，向所述细胞中引入所述一种 或多种多核苷酸可经一段时间执行至少两次，经一段时间执行至少三次，经一段时间执行至少四次，经一段时间执行至少五次，经一段时间执行至少六次，经一段时间执行至少七次，经一段时间执行至少八次，经一段时间执行至少九次，经一段时间执行至少十次，经一段时间执行至少十一次，经一段时间执行至少十二次，经一段时间执行至少十三次，经一段时间执行至少十四次，经一段时间执行至少十五次，经一段时间执行至少十六次，经一段时间执行至少十七次，经一段时间执行至少十八次，经一段时间执行至少十九次或经一段时间执行至少二十次。
在一些实施方案中，所述靶向载体(含有引入核酸)与表达载体(含有sgRNA)同时引入细胞中。
在一些实施方案中，进一步提供用于制造人源化非人类动物的方法，其包括：(a)用包含插入核酸的靶向载体修饰多潜能细胞的基因组以形成供体细胞，所述插入核酸包含人类核酸序列；(b)将所述供体细胞引入宿主胚胎中；和(c)在代孕母体中孕育所述宿主胚胎，其中所述代孕母体生成包含所述人类核酸序列的子代。在一些实施方案中，所述供体细胞引入处于胚泡段或处于前桑椹胚阶段(即，4-细胞阶段或8-细胞阶段)的宿主胚胎中。在更进一步的实施方案中，所述基因修饰能够经由种系传递。
在一些特定实施方案中，提供了用于制造人源化小鼠的方法，所述方法包括：(a)将包含ACE2基因片段的靶向载体与连接有sgRNA的表达载体引入小鼠胚胎细胞中，形成基因编辑的供体细胞；(b)将所述供体细胞引入小鼠胚胎中；和(c)在代孕母体中孕育所述小鼠胚胎，其中所述代孕母体生成包含所述人类ACE2序列的子代。
本文中，关于“四倍体互补技术”与“四倍体胚胎补偿技术”或“四倍体互补方法”或“四倍体胚胎互补方法”可以等同，其指的是将一定数量的胚胎干细胞(ES)细胞和四倍体胚胎嵌合，在其嵌合体的发育过程中，ES细胞和四倍体胚胎不是随机分布的，即其四倍体胚胎部分仅参与卵黄囊内胚层和胎盘滋养层细胞(如绒毛膜外胚层、滋养层细胞等)等胚外组织的形成，而ES细胞则广泛的参与胚体、尿囊、羊膜、卵黄囊中胚层和绒毛膜中胚层部分的生成，而不参与生成卵黄囊内胚层和胎盘滋养层细胞谱系，即二者的发育潜能具有互补性，这种现象称之为四倍体互补技术。
在一些情况中，术语“胚胎”是指来源于出生前任意时间的动物受试者或来源于出生前任意时间的动物受试者体内的组织和细胞。
在一些情况中，“胚胎”被用于描述在受精后八周变成胎儿前移植入子宫后的受精卵母细胞。根据该定义，受精的卵母细胞在进行移植前通常被称为胚前期(pre-embryo)。然而，贯穿该专利申请，我们将使用更宽的术语胚胎定义，其包括胚前期阶段。因此其包括从卵母细胞受精到桑葚胚、胚泡期孵化和植入的所有发育阶段。
胚胎近似球形并且由一个或多个由明胶样外壳包围的细胞(卵裂球)组成，无细胞的基质被称为透明带。透明带执行多种功能，直到胚胎孵化为止，并且透明带是用于胚胎评价的好标志。该带是球状且半透明的，并且应当清晰地区别于细胞碎片。
哺乳动物着床前胚胎，直径约90～120微米，外面包有清晰可见的由糖蛋白组成的透明带。在受精卵的一侧，可见1-2个减数分裂时形成的极体。
在受精后23-43.5小时之间卵子经过第一次有丝分裂后形成的具有2个卵裂球的胚胎。2-细胞期胚胎的细胞近椭圆形，大小基本相等，经电击后2个卵裂球可以融合成一个4倍体细胞，进而发育成4倍体胚胎。受精卵一分为二形成2个卵裂球即2-细胞期，进一步地，2个卵裂球再一分为二形成4个，即4-细胞期；再一分为二为8个，即8-细胞期，经过5次分裂到32个细胞的时候，即形成了“桑椹胚。在4-细胞期，可以看到4个卵裂球呈交错排列。8-细胞期卵裂球排列分成上下两层，随着紧密连接的形成开始出现致密化。16-细胞期开始被称为桑葚胚，出现内细胞团与滋养层分化。受精后72小时胚胎发育到32-细胞期，卵裂球之间出现缝隙，增大后形成完整的囊胚腔，腔的一侧集中有一团细胞，此即为内细胞团。围绕囊胚腔四周的一层扁平细胞，称为滋养层。此时囊胚也称为胚泡。晚期胚泡膨胀并挤出透明带，即为孵化胚泡。
术语胚胎被用来表示以下的各个阶段——受精卵母细胞、受精卵(zygote)、2-细胞、4-细胞、8-细胞、16-细胞、桑葚胚、胚泡、扩张胚泡和孵化胚泡，以及位于其间的所有阶段(例如3-细胞或5-细胞)。
本文中使用的术语“嵌合体囊胚”或“嵌合体胚胎”指的是包含胚胎干细胞的处于嵌合体状态的囊胚或胚胎。该嵌合体囊胚或胚胎除了通过注射方法生产以外，还可使用例如所谓“聚集方法”生产，在该“聚集方法”中，令胚胎+胚胎、或胚胎+细胞在有盖培养皿中彼此紧密粘附，以生产嵌合体囊胚。再者，本公开中的接纳者囊胚或胚胎与待移植的细胞之间的关系可以是同种异体关系或异种异体关系。
本文使用的术语“给予”或“移植”是指通过使细胞至少部分定位于期望位点从而产生期望效果的方法或途径，将细胞放置于受试者中。
例1 ACE2基因sgRNA1及pX330-sgRNA质粒构建
合成识别靶位点的sgRNA1序列。
sgRNA1序列(SEQ ID NO:1)：5’-tactgctcagtccctcaccgagg-3’
针对sgRNA位点引入BbsI酶切位点合成sgRNA的上下游退火引物进行后续退火实验。合成sgRNA1的上下游单链引物序列如下：
上游：5’-caccgcttggcattttcctcggtga-3’(SEQ ID NO:4)
下游：5’-aaactcaccgaggaaaatgccaagc-3’(SEQ ID NO:5)
pX330质粒来源：pX330载体图谱，参见图1。该质粒骨架来源淼灵质粒平台，货号P0123。
将上述sgRNA退火引物经退火后分别连接至pX330质粒(质粒先用BbsI线性化)，获得表达载体pX330-sgRNA1。
具体的连接反应体系如表1所示。
表1连接反应体系
sgRNA退火产物 1μL(0.5μM)
pX330-sgRNA载体 1μL(20ng)
T4 DNA Ligase 1μL(5U)
10×T4 DNA Ligase buffer 1μL
H 2O 补至10μL
反应条件为：16℃连接30min以上，转化至30μL TOP10感受态细胞中，然后取200μL涂布于Amp抗性的平板，37℃培养至少12小时后挑选2个克隆接种含有Amp抗性的LB培养基(5mL)中，37℃，250rpm摇培至少12小时。
随机挑选的克隆送测序公司进行测序验证，测序结果如图2所示，选择连接正确的表达载体pX330-sgRNA1进行后续实验。
例2 ACE2基因sgRNA2及pX330-sgRNA2质粒构建
合成识别靶位点的sgRNA2序列。
sgRNA2-序列(SEQ ID NO:2)：5’-cttggcattttcctcggtgaggg-3’
针对sgRNA位点引入BbsI酶切位点合成sgRNA的上下游退火引物进行后续退火实验。合成sgRNA2的上下游单链引物序列如下：
上游：5’-caccgtactgctcagtccctcaccg-3’(SEQ ID NO:6)
下游：5’-aaaccggtgagggactgagcagtac-3’(SEQ ID NO:7)
pX330质粒来源：pX330载体图谱，参见图1。该质粒骨架来源淼灵质粒平台，货号P0123。
将上述sgRNA退火引物经退火后分别连接至pX330质粒(质粒先用BbsI线性化)，获得表达载体pX330-sgRNA2。
具体的连接反应体系如表2所示。
表2连接反应体系
sgRNA退火产物 1μL(0.5μM)
pX330-sgRNA载体 1μL(20ng)
T4 DNA Ligase 1μL(5U)
10×T4 DNA Ligase buffer 1μL
H 2O 补至10μL
反应条件为：16℃连接30min以上，转化至30μL TOP10感受态细胞中，然后取200μL涂布于Amp抗性的平板，37℃培养至少12小时后挑选2个克隆接种含有Amp抗性的LB培养基(5mL)中，37℃，250rpm摇培至少12小时。
随机挑选的克隆送测序公司进行测序验证，测序结果如图3所示，选择连接正确的表达载体pX330-sgRNA2进行后续实验。
例3 pX330-sgRNA切割效率鉴定
分别将2μg例1、例2制备的pX330-sgRNA质粒利用脂质体3000(Lipofectamine 3000，invitrogen，货号L3000001)方法转染进小鼠胚胎干细胞，具体转染操作参考Lipofectamine 3000试剂操作说明。收取转染两天后的小鼠胚胎干细胞，用细胞基因组提取试剂盒进行基因组提取(天根，DP304-02)。随后在基因组切割位点两侧设计PCR上下游引物，上游引物(5arm-sgF：ggttttgatttggccataaaatgttagc(SEQ ID NO:10))和下游引物(3arm-sgR：attcccaggtccagtttcacctaag(SEQ ID NO:11))对提取所得基因组进行PCR反应(使用诺唯赞Phanta Max Super-FidelityDNA Polymerase)。然后利用T7核酸内切酶Ⅰ(T7EⅠ)(Biolabs，M0302L)进行pX330-sgRNA切割效率验证，原理T7核酸内切酶Ⅰ可识别并切割不完全配对DNA。
T7 EⅠ实验具体操作步骤：
将上述从各转染pX330-sgRNA1和pX330-sgRNA2的细胞提取基因组，通过5arm-sgF+3arm-sgR扩增得到的PCR产物进行回收(天根，DP214-02)，取1μg进行退火反应，体系如下所示：
表3
PCR产物 1μg
Buffer 2 2μL
H 2O 补至20μL
反应条件 水浴锅煮沸10min后自然冷却
然后往退火产物中加入1μL T7核酸内切酶Ⅰ于37℃反应30min，后直接跑胶验证。跑胶结果如图4所示。例1、例2的sgRNA1和sgRNA2其切割条带亮度较强(sgRNA1可切割成约376bp和581bp两条带，sgRNA2可切割成约371bp和586bp两条带)，具有较高切割效率。
由于切割效率主要通过图显示，为了显现例1、2的方案的效果，图4中同时列举了另一sgRNA(指代为sgRNA3)的切割效率。
所列举的sgRNRA3序列(SEQ ID NO:3)：5’-caagtgaactttgataagacagg-3’
合成sgRNA3的上下游单链引物序列如下：
上游：5’-caccgcaagtgaactttgataagac-3’(SEQ ID NO:8)
下游：5’-aaacgtcttatcaaagttcacttgc-3’(SEQ ID NO:9)
其余步骤如同例1。随机挑选克隆送测序公司进行测序验证，测序结果如图5所示，选择连接正确的表达载体pX330-sgRNA3进行后续实验。
由于其他的sgRNA及pX330-sgRNA质粒构建非本公开例的重点，因此不作过多赘述和列举。
例4打靶载体的设计
将人ACE2基因(Gene ID：ID:59272)CDS蛋白编码序列(基于NCBI登录号为NM_001371415.1→NP_001358344.1的转录本，其CDS序列(hACE2-CDS)如SEQ ID NO:12所示，蛋白序列(hACE2-protein)如SEQ ID NO:13所示)插入到鼠Ace2的启动子和5’UTR区域序列后，利用鼠Ace2启动子启动人ACE2基因表达。同时，插入的人ACE2 CDS序列后加上SV40 polyA序列信号(SV40-polyA序列如SEQ ID NO:14所示)终止信号加强人ACE2 mRNA转录停止。
根据序列设计，发明人进一步的设计了如图6所示的打靶方案和包含5’同源臂(5arm)、人ACE2基因片段、3’同源臂(3arm)的载体。其中5’同源臂为NCBI登录号为AC091606.8的第125683-126652位核苷酸(5’同源臂序列如SEQ ID NO:15所示)，3’同源臂为NCBI登录号为AC091606.8的第126796-127766位核苷酸(3’同源臂序列如SEQ ID NO:16所示)。同时，PGK-嘌呤霉素异种基因包也被插入载体用做筛选需要，嘌呤霉素抗性基因(PGK-puro，SEQ ID NO:17)表达框两端设计有一对同向的frt位点(SEQ ID NO:18)，因此可以利用FLP重组酶去除从而解决转基因引起的安全问题。构建的载体被进行完全序列验证。在靶向之前，通过AgeI，所述载体被线性化(打靶载体示意图和打靶策略示意图如图6所示)。
载体构建过程如下：
设计扩增5’同源臂的搭桥片段的上游引物(5arm-pcrF：tcgcacacattccacatccaccggtccctatggagtggagaagagtctta(SEQ ID NO:19))和与其匹配的下游引物(5arm-pcrR：gaaggagccaggaagagcttgacatctttccccgtgcgccaagatcc(SEQ ID NO:20))；
设计扩增人ACE2 CDS的搭桥片段的上游引物(hACE2-F：ggatcttggcgcacggggaaagatgtcaagctcttcctggctccttc(SEQ ID NO:21))和与其匹配的下游引物(hACE2-R：cattataagctgcaataaacaagttctaaaaggaggtctgaacatcatc(SEQ ID NO:22))；
设计扩增SV40 polyA的搭桥片段的上游引物(SV40-F：gatgatgttcagacctccttttagaacttgtttattgcagcttataatg(SEQ ID NO:23))和与其匹配的下游引物(SV40-R：AGAGAATAGGAACTTCGCACGCGTtaagatacattgatgagtttggac(SEQ ID NO:24))；
设计扩增3’同源臂片段的上游引物(3arm-pcrF：tacgaagttatGtcgacgcGGCGCGCCgaattataatactaacattactg(SEQ ID NO:25))和与其匹配的下游引物(3arm-pcrR：tatgaccatgattacgccaagcttaagaccaaactattagagcagttaaaagc(SEQ ID NO:26))。5’同源臂与3’同源臂的扩增模板为C57BL6/J小鼠基因组，人ACE2的扩增模板为人肺细胞cDNA。PCR反应体系(使用诺唯赞Phanta Max Super-FidelityDNA Polymerase)和条件见表4：
表4 PCR反应体系(50μL)
2×Phanta Max Buffer 25μL
dNTP Mix 1μL
上游引物(10μM) 2μL
下游引物(10μM) 2μL
Phanta Max Super-Fidelity DNA Polymerase 1μL
模板 5’同源臂、人ACE2 CDS、SV40 polyA片段各50ng
H 2O 补至50μL
PCR扩增反应条件 65℃起始，每个循环降0.3℃
如是，将PCR扩增得到的产物片段5’同源臂、人ACE2 CDS、SV40 polyA使用搭桥PCR(overlap PCR)搭配Touch down PCR方法PCR成连续片段5arm-hACE-SV40；以及PCR扩增得到的3’同源臂回收后直接用于构建同源重组打靶载体，构建过程如下：
1.将5arm-hACE-SV40片段进行AgeI+MluI双酶切；3’同源臂片段进行AscI+HindIII双酶切后分别通过酶切连接的方法连接上去，从而得打靶载体。
2.通过酶切鉴定后将获得的阳性打靶载体送去测序鉴定，经测序公司验证序列正确(如图7)，从而成功获得人源化ACE2打靶载体，整个打靶载体序列如SEQ ID NO:27所示。
例5
将PCR扩增得到的产物片段5’同源臂、人ACE2 CDS、SV40 polyA使用搭桥PCR(overlap PCR)方法PCR成连续片段5arm-hACE-SV40，PCR反应条件如表5所示，其余条件同例4。
表5 PCR反应体系(50μL)
2×Phanta Max Buffer 25μL
dNTP Mix 1μL
上游引物(10μM) 2μL
下游引物(10μM) 2μL
Phanta Max Super-Fidelity DNA Polymerase 1μL
模板 5’同源臂、人ACE2 CDS、SV40 polyA片段各50ng
H 2O 补至50μL
PCR扩增反应条件 65℃
结果如图8所示，并未能扩增出3片段连接片段。
例6人源化ACE2小鼠胚胎干细胞的获得
其中一个实施方式中，人源化ACE2小鼠胚胎干细胞的获得可按照如下方法进行：
(1)C57BL6/J小鼠胚胎干细胞(所述的胚胎干细胞来源于已确立的胚胎干细胞系)从液氮冻存细胞库中复苏，特别使用代数为p10以内的小鼠胚胎干细胞，在6cm培养皿中培养生长3天。
(2)通过配套使用Nucleofector TM IIs/2b电转仪以及Mouse ES Cell
Figure PCTCN2020101681-appb-000001
Kit(Lonza，VPH-1001)小鼠胚胎干细胞电转试剂盒，使用A023程序，约2×10 6个胚胎干细胞被电穿孔，并且所述电转过程在含有3μg线性化打靶载体(例4打靶载体)以及1μg pX330-sgRNA1的100μL电转缓冲液中进行。所述转染细胞被种到3个6孔板的孔中培养，恢复36小时。恢复后，1μg/mL嘌呤霉素(默克公司)被加入到细胞培养基中。
经过3-4天的筛选后，通过使用玻璃拉针吸取单克隆的方式挑取嘌呤霉素抗性小鼠胚胎干细胞克隆进96孔板中培养。第二天将单克隆通过胰酶消化并分成两份，其中一份细胞在10μL的NP 40裂解缓冲液中于56℃下单独地裂解60分钟，随后在95℃下裂解10分钟。
其中，另外一份小鼠胚胎干细胞培养的具体步骤：提前一天准备饲养层feeder细胞，按照需求铺在不同的孔板中，过夜培养形成单层。其 中饲养层feeder细胞为经丝裂霉素C(MMC)法处理制备的小鼠胚胎成纤维细胞。使用含有LIF和2i(chir99021和pD0325901 inhibitor)的mES培养基培养，每天更换新鲜培养基，可根据细胞的长势适当增加培养基，一般3天传一代，传代时用0.25％胰酶消化，按照6厘米盘30万、6孔板10万每孔左右的密度种植。
mES+LIF+2i培养基组成为：Knockout DMEM(1×,gibco)+15％FBS(FRONT BIOMEDICAL,0.22μm Millipore滤器过滤)+GlutaMAX(100×,gibco)+NEAA(100×,gibco)+P/S(P:50units,S:50mg/ml,Hyclone)+β-mercaptoethanol(gibco，使用浓度0.1mM)+LIF(1000units/ml,Millipore)+CHIR99021(GSK3β抑制剂，使用浓度3μM)+PD0325901(MEK抑制剂，使用浓度1μM)。
NP40裂解液的组成为：10mL TE(20mM Tris pH8.0，150mM NaCl，2mM EDTA)+0.5％NP40+10μL蛋白酶K(10mg/mL)。
上述方法中的pX330-sgRNA1替换成pX330-sgRNA2或pX330-sgRNA3，其他步骤同pX330-sgRNA1。
pX330-sgRNA1、pX330-sgRNA2和pX330-sgRNA3搭配打靶载体打靶效果如表6所示。
表6.sgRNA1-3搭配打靶载体打靶效果(存活克隆数)
pX330-sgRNA1 pX330-sgRNA2 pX330-sgRNA3
231 187 43
例7人源化ACE2小鼠胚胎干细胞基因型鉴定
例6最后得到的细胞裂解物用作基因型鉴定PCR筛选模板。通过使用Phanta Max Super-FidelityDNA Polymerase试剂(诺唯赞公司)，根据制造商的说明书实施PCR筛选。PCR分析用于定向插入小鼠Ace2位点的具有5’同源臂和3’同源臂的HDR。由于ACE2基因位于X染色体上，使用的小鼠胚胎干细胞为XY雄性，所以不存在双等位基因靶向发生。
鉴定定向插入引物的上游位于嘌呤霉素抗性内部(Puro-F：aacctccccttctacgagc(SEQ ID NO:28))，与其配对的引物下游位于3’同源臂的外侧(3arm-outR：tacagccaggatctggatgtcagc(SEQ ID NO:29))。如果重组载体插入位置正确，则应出现一条长度应为1504bp的条带。此时小鼠胚胎干细胞Ace2位点基因组序列替换为SEQ ID NO:30。
PCR鉴定结果见图9，共鉴定了14株克隆，其中标注*号为阳性克隆，同时PCR产物经测序结果匹配一致。此PCR结果阳性的小鼠胚胎干细胞克隆为成功编辑的人源化小鼠胚胎干细胞模型，但其中还保留有PGK-Puro筛选标志，由于PGK-Puro两端具有一对同向的frt位点，因此可以利用FLP重组酶去除从而解决转基因引起的安全问题。
PGK-Puro筛选标志的删除方法如下：
将上述PCR结果阳性的小鼠胚胎干细胞继续培养至6cm盘，通过配套使用Nucleofector TM IIs/2b电转仪以及Mouse ES Cell
Figure PCTCN2020101681-appb-000002
Kit(Lonza，VPH-1001)小鼠胚胎干细胞电转试剂盒，使用A023程序，约2×10 6个细胞被电穿孔，并且所述电转过程含有pPGK-FLPo质粒(Addgene，13793)的100μL电转缓冲液中进行。所述转染细胞被种到6个12孔板的孔中，3天后，采取玻璃拉针吸取单克隆的方式挑取小鼠胚胎干细胞克隆进96孔板中培养，第二天将单克隆消化传代一分为二，一份进行嘌呤霉素筛选，一份正常培养。若成功删除PGK-Puro抗性筛选标志，则嘌呤霉素筛选后细胞不耐受死亡。嘌呤霉素不耐受相对应的克隆可使用上游引物(hACE2-F：tgatagtggttggcattgt(SEQ ID NO:31))和下游引物(3arm-outR：tacagccaggatctggatgtcagc(SEQ ID NO:29))进行基因组基因型PCR鉴定。若成功删除PGK-Puro筛选标志，则PCR产物长度为1532bp，删除PGK-Puro前的PCR产物长度为2863bp。基因型鉴定结果如图9所示，跑胶条带在1500bp处的为成功删除PGK-puro后的克隆，条带在3000bp处的为删除前克隆。嘌呤霉素不耐受相对应的克隆则为最终成功编辑为人源化ACE2打靶的小鼠胚胎干细胞，也就是小鼠胚胎干细胞最终获得如图10所示的人源化ACE2基因。最终删除PGK-puro后小鼠胚胎干细胞Ace2位点基因组序列替换为如SEQ ID NO:32所示的序列。
例8人源化ACE2基因改造小鼠的形成
1、腹腔注射7.5单位PMSG到4-10周龄B6C3F1雌鼠，48小时后注射hCG并与CD1种公鼠合笼，次日早上检查雌鼠阴栓并将有阴栓的雌鼠挑出，记录雌鼠相应的受精时间。2、下一日将孕鼠进行颈椎脱臼法安乐死，70％酒精消毒小鼠腹部，用辅料镊子和眼科剪刀剪开腹部皮肤和肌肉层，打开腹腔。用镊子抓住一个子宫角的上部，用剪刀在靠近输卵管的膜上开一个小口，将输卵管和卵巢连接处剪断，将输卵管和附带的子宫移至35mm培养皿中，用镊子固定好输卵管伞口端，用装填好M2培养液(Hogan,B.(1994).Manipulating the mouse embryo:a laboratory manual,2nd edn(Cold Spring Harbor,NY,Cold Spring Harbor Laboratory Press).)的冲洗针轻轻插入伞口，用0.1mL的M2培养液冲洗输卵管，用移卵管收集冲出的胚胎并用M2清洗3次，收集E1.5的小鼠2-细胞胚胎。
3、对收集到的小鼠胚胎放入含0.1mM MgSO4,0.1mM CaCl 2和0.3％牛血清白蛋白的0.3M甘露醇(Sigma-Aldrich Inc.,St.Louis,MO)中，用 Cellfusion CF-150/B电融合仪和250-um融合槽(BLS Ltd.,Budapest,Hungary)进行60V 50微秒直流电融合，获得4倍体胚胎；放入KSOM培养基(Summers,M.C.,McGinnis,L.K.,Lawitts,J.A.,Raffin,M.,and Biggers,J.D.(2000).IVF of mouse ova in a simplex optimized medium supplemented with amino acids.Hum Reprod 15,1791-1801.)，于CO2培养箱中培养24小时后用酸性台氏液(Sigma-Aldrich，T1788)去掉透明带，与胚胎干细胞(例6获得的人源化ACE2小鼠胚胎干细胞)聚集，形成嵌合体胚胎(Nagy,A.,Rossant,J.,Nagy,R.,Abramow-Newerly,W.,and Roder,J.C.(1993).Derivation of completely cell culture-derived mice from early-passage embryonic stem cells.Proc Natl Acad Sci U S A 90,8424-8428.)。
4、于CO 2培养箱中培养过夜，移植到E2.5天的假孕鼠子宫，17天后在将代孕鼠颈椎脱臼法安乐死后进行剖腹手术，存活和呼吸的新生鼠放入代乳鼠笼内，21天后断奶，获得完全来自胚胎干细胞的转基因小鼠，即得人源化ACE2基因改造小鼠(图12)。
相应的培养基配方如表7所示。
表7培养基配方
培养基 KSOM(200mL) M2(200mL)
EDTA(disodium 0.01mM) 0.00076g /
NaCl 1.119g 1.1068g
KCl 0.037g 0.070g
CaCl2·2H2O 1.71mM 1.71mM
KH2PO4 0.0095g 0.032g
MgSO4 0.00482g 0.0283g
NaHCO3 0.420g 0.070g
Na lactate 0.280mL 0.62mL
Na pyruvate 0.0044g 0.0073g
Glucose 0.0072g 0.1g
Pen/Strep/Glu 1mL 2mL
HEPES / 0.994g
EDTA(100mM) / 200μL
Gentamycin / 200μL
Phenol red(0.5％) 20μL 100μL
BSA 0.2g 0.8g
水 加水至200mL 加水至200mL
例9人源化ACE2小鼠表达鉴定
对新生人源化ACE2小鼠以及野生型小鼠进行解剖，分别取出肺、肾、肠，用Trizol进行裂解，然后用细胞/组织总RNA提取试剂盒进行RNA提取(诺唯赞，RC101-01)以及用HiScript II Q RT SuperMix for qPCR试剂进行反转(诺唯赞，R222-01)。对提取组织的cDNA用hACE2特异引物(hACE2-qF：TGATAGTGGTTGGCATTGT，hACE2-qR：CGATGGAGGCATAAGGATT)以及mACE2特异引物(mACE2-qF：GGTTGGCATCATCATCCT；mACE2-qR：GTCTGAGCATCATCACTGT)进行qPCR检测(诺唯赞，Q321-02)显示，人源化ACE2小鼠组织特异表达hACE2，而野生型小鼠不表达hACE2(图13)，且hACE2小鼠其mACE2表达缺失(图14)。进一步的，我们分别取hACE2小鼠以及野生型ACE2小鼠的肠组织进行免疫印迹实验，用人特异ACE2抗体(Abcam，ab108209)进行用于十二烷基硫酸钠聚丙烯酰胺凝胶电泳法(SDS-PAGE)确定了hACE2小鼠在蛋白水平上表达hACE2蛋白(图15)。
例10小鼠的制备方法(2-细胞期/提高了Mg 2+和Ca 2+浓度的电融合液组)
本例使用的小鼠胚胎干细胞为上述例6、例7获得的嘌呤霉素不耐受的人源化ACE2打靶的小鼠胚胎干细胞。具体实验的时候，是从液氮冻存细胞库中复苏，特别使用代数为p15以内的胚胎干细胞，在6cm培养皿中培养生长3天。本例中使用的是第12代的胚胎干细胞。
1、例10中使用的溶液配方分别如表8-表10所示。
表8电融合液配方(提高了Mg 2+和Ca 2+浓度的电融合液)
Figure PCTCN2020101681-appb-000003
表9培养基配方
培养基 KSOM(200mL) M2(200mL)
EDTA(disodium 0.01mM) 0.00076g /
NaCl 1.119g 1.1068g
KCl 0.037g 0.070g
CaCl 2·2H 2O 1.71mM 1.71mM
KH 2PO 4 0.0095g 0.032g
MgSO 4 0.00482g 0.0283g
NaHCO 3 0.420g 0.070g
Na lactate 0.280mL 0.62mL
Na pyruvate 0.0044g 0.0073g
Glucose 0.0072g 0.1g
Pen/Strep/Glu 1mL 2mL
HEPES / 0.994g
EDTA(100mM) / 200μL
Gentamycin / 200μL
Phenol red(0.5％) 20μL 100μL
BSA 0.2g 0.8g
水 加水至200mL 加水至200mL
表10酸性台氏液
Figure PCTCN2020101681-appb-000004
2、小鼠的制备
(1)腹腔注射7.5单位PMSG到4-10周龄B6C3F1雌鼠，48小时后注射hCG并与CD1种公鼠合笼，次日早上检查雌鼠阴栓并将有阴栓的雌鼠挑出，记录雌鼠相应的受精时间。
(2)下一日将孕鼠进行颈椎脱臼法安乐死，70％酒精消毒小鼠腹部，用辅料镊子和眼科剪刀剪开腹部皮肤和肌肉层，打开腹腔。用镊子抓 住一个子宫角的上部，用剪刀在靠近输卵管的膜上开一个小口，将输卵管和卵巢连接处剪断，将输卵管和附带的子宫移至35mm培养皿中，用镊子固定好输卵管伞口端，用装填好M2培养液(Hogan,1994)的冲洗针轻轻插入伞口，用0.1mL的M2培养液冲洗输卵管，用移卵管收集冲出的胚胎并用M2清洗3次，收集E1.5(受精后1.5天)的小鼠2-细胞胚胎。
(3)将收集到的小鼠2-细胞胚胎放入改进的电融合液(表8所述的配方)中，用Cellfusion CF-150/B电融合仪和250-微米电极间距的融合槽(BLS Ltd.,Budapest,Hungary)进行60伏50微秒直流电融合，从而获得四倍体胚胎，之后将融合的胚胎放入KSOM培养基(Summers et al.,2000)，于CO 2培养箱中培养15小时。结果显示，改进的电融合液的融合效率达到100％。
(4)四倍体胚胎发育到2-细胞期，用酸性台氏液去掉透明带，与用0.25％胰酶消化后的小串胚胎干细胞聚集，再培养24小时后形成嵌合体胚胎。
(5)最后，将嵌合体胚胎移入怀孕2.5天的假孕鼠子宫，17天后可获得足月发育的新生鼠。
由于四倍体胚胎只能有效形成胎盘等胚外组织，从四倍体胚胎与胚胎干细胞嵌合体胚胎获得的新生鼠完全来源于胚胎干细胞。
本例制备小鼠的流程示意图如图16所示。小鼠出生率的结果如图18所示，从图18可以看出，例10的方法制备的小鼠存活率达到25％(10/40)。
试验例1
除了胚胎干细胞的获得与例10不同，其他的与例10操作步骤一样。
本例中，小鼠胚胎干细胞为普通的未经基因修饰的胚胎干细胞，其获得按照如下方法进行：C57BL6/J小鼠胚胎干细胞从液氮冻存细胞库中复苏，使用代数为p12的小鼠胚胎干细胞，在6cm培养皿中培养生长3天。
制备小鼠的流程示意图如图16所示。小鼠出生率的结果如图19所示，从图19可以看出，试验例1的方法制备的小鼠存活率达到33.3％(48/144)。
例11小鼠的制备方法(2-细胞期/传统融合液组)
本例使用的小鼠胚胎干细胞为上述例6、例7获得的嘌呤霉素不耐受的人源化ACE2打靶的小鼠胚胎干细胞。具体实验的时候，是从液氮冻存细胞库中复苏，特别使用代数为p15以内的胚胎干细胞，在6cm培养皿中培养生长3天。本例中使用的是第12代的胚胎干细胞。
其中KSOM培养基和M2培养液与例10相同。
1.腹腔注射7.5单位PMSG到4-10周龄B6C3F1雌鼠，48小时后注射hCG并与CD1种公鼠合笼，次日早上检查雌鼠阴栓并将有阴栓的雌鼠挑出，记录雌鼠相应的受精时间；
2.下一日将孕鼠进行颈椎脱臼法安乐死，70％酒精消毒小鼠腹部，用辅料镊子和眼科剪刀剪开腹部皮肤和肌肉层，打开腹腔。用镊子抓住一个子宫角的上部，用剪刀在靠近输卵管的膜上开一个小口，将输卵管和卵巢连接处剪断，将输卵管和附带的子宫移至35mm培养皿中，用镊子固定好输卵管伞口端，用装填好M2培养液(Hogan,1994)的冲洗针轻轻插入伞口，用0.1mL的M2培养液冲洗输卵管，用移卵管收集冲出的胚胎并用M2清洗3次，收集E1.5的小鼠2-细胞胚胎。
3.将收集到的小鼠2-细胞胚胎放入电融合液中(表11所示的配方)，用Cellfusion CF-150/B电融合仪和250-微米电极间距的融合槽(BLS Ltd.,Budapest,Hungary)进行60伏50微秒直流电融合，从而获得四倍体胚胎，之后将融合的胚胎放入KSOM培养基(Summers et al.,2000)，于CO2培养箱中培养24小时。结果显示，融合效率为80-90％，电融合效率达不到100％。
4.四倍体胚胎发育到2-细胞期，用酸性台氏液去掉透明带，与用0.25％胰酶消化后的小串胚胎干细胞聚集，再培养24小时后形成嵌合体胚胎，或者培养48小时到囊胚期，将胚胎干细胞通过显微操作注入囊胚腔中(Nagy et al.,1993)。
5.最后，将嵌合体胚胎移入怀孕2.5天的假孕鼠子宫，17天后可获得足月发育的新生鼠。由于四倍体胚胎只能有效形成胎盘等胚外组织，从四倍体胚胎与胚胎干细胞嵌合体胚胎获得的新生鼠完全来源于胚胎干细胞。
表11电融合液的配方(传统融合液)
Figure PCTCN2020101681-appb-000005
Figure PCTCN2020101681-appb-000006
制备小鼠的流程示意图如图16所示。本实施的小鼠出生率的结果如图18所示。从图18可以看出，小鼠的存活率为14.2％(15/106)。
试验例2
除了胚胎干细胞的获得与例11不同，其他的与例11操作一样。
本例中，小鼠胚胎干细胞为普通的未经基因修饰的胚胎干细胞，其获得按照如下方法进行：C57BL6/J小鼠胚胎干细胞从液氮冻存细胞库中复苏，使用代数为p12的小鼠胚胎干细胞，在6cm培养皿中培养生长3天。
制备小鼠的流程示意图如图16所示。小鼠出生率的结果如图19所示，从图19可以看出，小鼠的存活率为21.1％(32/152)。
例12小鼠的制备方法(4-细胞期/提高了Mg 2+和Ca 2+浓度的电融合液组)
本例使用的小鼠胚胎干细胞为上述例6、例7获得的嘌呤霉素不耐受的人源化ACE2打靶的小鼠胚胎干细胞。具体实验的时候，是从液氮冻存细胞库中复苏，特别使用代数为p15以内的胚胎干细胞，在6cm培养皿中培养生长3天。本例中使用的是第12代的胚胎干细胞。
其中KSOM培养基和M2培养液与例10相同。
1.腹腔注射7.5单位PMSG到4-10周龄B6C3F1雌鼠，48小时后注射hCG并与CD1种公鼠合笼，次日早上检查雌鼠阴栓并将有阴栓的雌鼠挑出，记录雌鼠相应的受精时间；
2.下一日将孕鼠进行颈椎脱臼法安乐死，70％酒精消毒小鼠腹部，用辅料镊子和眼科剪刀剪开腹部皮肤和肌肉层，打开腹腔。用镊子抓住一个子宫角的上部，用剪刀在靠近输卵管的膜上开一个小口，将输卵管和卵巢连接处剪断，将输卵管和附带的子宫移至35mm培养皿中，用镊子固定好输卵管伞口端，用装填好M2培养液(Hogan,1994)的冲洗针轻轻插入伞口，用0.1ml的M2培养液冲洗输卵管，用移卵管收集冲出的胚胎并用M2清洗3次，收集E1.5的小鼠2-细胞胚胎。
3.将收集到的小鼠2-细胞胚胎放入电融合液中(表12所示的配方)，用Cellfusion CF-150/B电融合仪和250-微米电极间距的融合槽(BLS Ltd.,Budapest,Hungary)进行60伏50微秒直流电融合，从而获得四倍体胚胎，之后将融合的胚胎放入KSOM培养基(Summers et al.,2000)，于CO2培养箱中培养24小时。结果显示，改进的电融合液的融合效率达到100％。
4.四倍体胚胎发育到4-细胞期，用酸性台氏液去掉透明带，与用0.25％胰酶消化后的小串胚胎干细胞聚集，再培养24小时后形成嵌合体胚胎，或者培养48小时到囊胚期，将胚胎干细胞通过显微操作注入囊胚腔中(Nagy et al.,1993)。
5.最后，将嵌合体胚胎移入怀孕2.5天的假孕鼠子宫，17天后可获得足月发育的新生鼠。由于四倍体胚胎只能有效形成胎盘等胚外组织，从四倍体胚胎与胚胎干细胞嵌合体胚胎获得的新生鼠完全来源于胚胎干细胞。
表12电融合液配方(提高了Mg2+和Ca2+浓度的电融合液)
Figure PCTCN2020101681-appb-000007
制备小鼠的流程示意图如图17所示。
本实施的小鼠出生率的结果如图18所示。从图18可以看出，小鼠的存活率为2.5％(3/121)。
试验例3
除了胚胎干细胞的获得与例12不同，其他的与例12操作一样。
本例中，小鼠胚胎干细胞为普通的未经基因修饰的胚胎干细胞，其获得按照如下方法进行：C57BL6/J小鼠胚胎干细胞从液氮冻存细胞库 中复苏，使用代数为p12的小鼠胚胎干细胞，在6cm培养皿中培养生长3天。
制备小鼠的流程示意图如图17所示。小鼠出生率的结果如图19所示，从图19可以看出，小鼠的存活率为7.5％(9/120)。
例13小鼠的制备方法(4-细胞期/传统融合液组)
本例使用的小鼠胚胎干细胞为上述例6、例7获得的嘌呤霉素不耐受的人源化ACE2打靶的小鼠胚胎干细胞。具体实验的时候，是从液氮冻存细胞库中复苏，特别使用代数为p15以内的胚胎干细胞，在6cm培养皿中培养生长3天。本例中使用的是第12代的胚胎干细胞。其中KSOM培养基和M2培养液与例10相同。
1.腹腔注射7.5单位PMSG到4-10周龄B6C3F1雌鼠，48小时后注射hCG并与CD1种公鼠合笼，次日早上检查雌鼠阴栓并将有阴栓的雌鼠挑出，记录雌鼠相应的受精时间；
2.下一日将孕鼠进行颈椎脱臼法安乐死，70％酒精消毒小鼠腹部，用辅料镊子和眼科剪刀剪开腹部皮肤和肌肉层，打开腹腔。用镊子抓住一个子宫角的上部，用剪刀在靠近输卵管的膜上开一个小口，将输卵管和卵巢连接处剪断，将输卵管和附带的子宫移至35mm培养皿中，用镊子固定好输卵管伞口端，用装填好M2培养液(Hogan,1994)的冲洗针轻轻插入伞口，用0.1ml的M2培养液冲洗输卵管，用移卵管收集冲出的胚胎并用M2清洗3次，收集E1.5的小鼠2-细胞胚胎。
3.将收集到的小鼠2-细胞胚胎放入电融合液(表13所示的配方)中，用Cellfusion CF-150/B电融合仪和250-微米电极间距的融合槽(BLS Ltd.,Budapest,Hungary)进行60伏50微秒直流电融合，从而获得四倍体胚胎，之后将融合的胚胎放入KSOM培养基(Summers et al.,2000)，于CO2培养箱中培养24小时。电融合效率为80-90％。
4.四倍体胚胎发育到4-细胞期，用酸性台氏液去掉透明带，与用0.25％胰酶消化后的小串胚胎干细胞聚集，再培养24小时后形成嵌合体胚胎，或者培养48小时到囊胚期，将胚胎干细胞通过显微操作注入囊胚腔中(Nagy et al.,1993)。
5.最后，将嵌合体胚胎移入怀孕2.5天的假孕鼠子宫，17天后可获得足月发育的新生鼠。由于四倍体胚胎只能有效形成胎盘等胚外组织，从四倍体胚胎与胚胎干细胞嵌合体胚胎获得的新生鼠完全来源于胚胎干细胞。
表13电融合液的配方(传统融合液)
Figure PCTCN2020101681-appb-000008
本例5制备小鼠的过程和结果如图17所示。从图17可以看出，小鼠制备效率非常低。进一步地，小鼠出生率的结果如图18所示。从图18可以看出，小鼠的存活率仅为0.3％(1/350)。
试验例4
除了胚胎干细胞的获得与例13不同，其他的与例13操作一样。
本例中，小鼠胚胎干细胞为普通的未经基因修饰的胚胎干细胞，其获得按照如下方法进行：C57BL6/J小鼠胚胎干细胞从液氮冻存细胞库中复苏，使用代数为p12的小鼠胚胎干细胞，在6cm培养皿中培养生长3天。
制备小鼠的流程示意图如图17所示。小鼠出生率的结果如图19所示，从图19可以看出，小鼠的存活率仅为2.5％(4/163)。

Claims (17)

  1. 一种制备嵌合体胚胎的方法，所述方法包括将四倍体胚胎与胚胎干细胞聚合形成新的重构胚或嵌合体胚胎；所述的四倍体胚胎为处于2-细胞期的四倍体胚胎；
    优选地，所述方法使用了四倍体补偿法或四倍体胚胎互补法；
    优选地，所述方法包括以下步骤：
    (1)获得动物2-细胞胚胎；
    (2)将步骤(1)所述的2-细胞胚胎放入融合液中，进行融合，获得四倍体胚胎；
    (3)将步骤(2)中的四倍体胚胎放入培养基中培养；
    (4)将步骤(3)中发育到2-细胞期的四倍体胚胎与胚胎干细胞聚合，形成嵌合体胚胎；
    优选地，步骤(3)中的培养时间约为8-24小时；
    或优选地，步骤(3)中培养基为KSOM培养基。
  2. 一种非人动物的制备方法，其特征在于，所述方法包括将四倍体胚胎与胚胎干细胞聚合形成新的重构胚或嵌合体胚胎；所述的四倍体胚胎为处于2-细胞期的四倍体胚胎；
    优选地，所述方法使用了四倍体补偿法或四倍体胚胎互补法；
    优选地，所述方法包括以下步骤：
    (1)获得动物2-细胞胚胎；
    (2)将步骤(1)所述的2-细胞胚胎放入融合液中，进行融合，获得四倍体胚胎；(3)将步骤(2)中的四倍体胚胎放入培养基中培养；
    (4)将步骤(3)中发育到2-细胞期的四倍体胚胎与胚胎干细胞聚合，形成嵌合体胚胎；
    优选地，步骤(3)中的培养时间约为8-24小时；
    或优选地，步骤(3)中培养基为KSOM培养基。
  3. 如权利要求1或2所述的方法，所述动物为哺乳动物；
    优选地，所述动物为非人类哺乳动物；
    优选地，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴；
    优选地，所述动物选自鼠；
    优选地，所述动物选自成鼠；
    优选地，所述动物选自胎鼠；
    优选地，所述动物为基因编辑动物；
    优选地，所述动物为基因人源化动物；
    优选地，所述基因为ACE2。
  4. 如权利要求1或2所述的方法，所述融合使用了一种组合物，所述组合物成分包括甘露醇、MgSO 4、CaCl 2和牛血清白蛋白；所述甘露醇、MgSO 4、CaCl 2和牛血清白蛋白的质量比为9～53：0.015～0.241：0.013～0.23：0.01～5；
    优选地，所述组合物中甘露醇、MgSO 4、CaCl 2和牛血清白蛋白的质量比为18～52：0.018～0.241：0.016～0.23：0.01-4；
    优选地，所述组合物中甘露醇、MgSO 4、CaCl 2和牛血清白蛋白的质量比为27～52：0.018～0.12：0.016～0.1：1～3.5；
    优选地，所述组合物包括以下成分：甘露醇0.05-0.29M、MgSO 40.12-2mM、CaCl 20.12-2mM、牛血清白蛋白0.01-5mg/mL；
    优选地，所述组合物包括以下成分：甘露醇0.1-0.28M、MgSO 40.15-2mM、CaCl 20.15-2mM、牛血清白蛋白0.01-4mg/mL；
    优选地，所述组合物包括以下成分：甘露醇0.15-0.28M、MgSO 40.15-1mM、CaCl 20.15-1mM、牛血清白蛋白1-3.5mg/mL；
    更为优选地，所述组合物包括以下成分：甘露醇0.18-0.28M、MgSO 40.15-0.5mM、CaCl 20.15-0.5mM、牛血清白蛋白2-3.5mg/mL；
    更进一步优选地，所述组合物包括以下成分：甘露醇0.2-0.28M、MgSO 40.15-0.3mM、CaCl 20.15-0.3mM、牛血清白蛋白2-3mg/mL；
    优选地，所述组合物为电融合液；
    或优选地，所述电融合液含有甘露醇、牛血清白蛋、Mg 2+和Ca 2+，所述电融合液具有提高了浓度的Mg 2+和Ca 2+；或者，所述电融合液Mg 2+和Ca 2+的浓度分别为0.12-2mM、0.12-2mM；
    优选地，所述的电融合液体中的甘露醇、牛血清白蛋的浓度分别为0.05-0.29M、0.01-5mg/mL；
    更为优选地，所述的Mg 2+和Ca 2+分别来源于MgSO 4和CaCl 2；
    更为优选地，所述电融合液用于制备四倍体胚胎。
  5. 一种非人动物或其子孙的组织、体液、细胞、以及它们的破碎物或提取物，所述的非人动物是由权利要求2-4任一所述的方法制备的。
  6. 一种非人动物，是由权利要求1-4任一所述的方法制备的。
  7. 一种引物组合，所述引物组合包括与如SEQ ID NO:19所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:20所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物。
  8. 如权利要求7所述的引物组合，所述引物组合还包括与如SEQ ID NO:21所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:22所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物；
    优选地，所述引物组合还包括与如SEQ ID NO:23所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:24所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物；
    更为优选地，所述引物组合还包含与如SEQ ID NO:25所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:26所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物。
  9. 权利要求7或8所述的引物组合在制备细胞株或细胞系或非人动物中的应用；
    优选地，所述动物为哺乳动物；
    优选地，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩或猴；
    优选地，所述哺乳动物为啮齿类动物；
    优选地，所述动物为鼠；
    优选地，所述动物选自成鼠；
    优选地，所述动物选自胎鼠；
    优选地，所述动物为基因人源化动物；
    优选地，所述基因为ACE2。
  10. 一种打靶载体，包含5’同源臂序列、人源ACE2基因片段和SV40 polyA序列连接在一起；
    优选地，所述5’同源臂为与在所述目标基因组基因座处的5’靶序列同源的5’同源臂；
    优选地，所述打靶载体通过权利要求7或8所述的引物组合连接5’同源臂序列、人源ACE2基因片段和SV40 polyA序列；
    优选地，所述靶向载体用于将人源ACE2基因的CDS序列插入到动物基因的启动子和5’UTR区域序列后，利用动物目的基因启动子启动人目的基因表达；
    优选地，所述5’同源臂序列与如SEQ ID NO:15所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性；
    优选地，所述ACE2基因的CDS序列与如SEQ ID NO:12所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性；
    优选地，所述SV40 polyA序列与如SEQ ID NO:14所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性；
    优选地，所述SV40 polyA序列位于所述的CDS序列之后；
    优选地，所述打靶载体还包含3’同源臂，所述3’同源臂为与在所述目标基因组基因座处的3’靶序列同源的3’同源臂；
    优选地，所述3’同源臂的序列与如SEQ ID NO:16所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性；
    优选地，所述打靶载体还包含与如SEQ ID NO:17所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的筛选标志PGK-Puro；
    优选地，所述打靶载体还包含与如SEQ ID NO:18所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的Frt序列；
    优选地，所述打靶载体各个序列片段的连接顺序依次为5’同源臂序列、人源ACE2基因片段、SV40 polyA序列、frt序列、PGK-Puro序列、frt序列和3’同源臂序列；
    优选地，所述动物为哺乳动物；
    优选地，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴；
    优选地，所述哺乳动物为啮齿类动物；
    优选地，所述动物为鼠；
    优选地，所述动物选自成鼠；
    优选地，所述动物选自胎鼠；
    优选地，所述动物为基因人源化动物；
    优选地，所述基因为ACE2。
  11. 权利要求10所述的打靶载体在制备非人动物中的应用；
    优选地，所述动物为哺乳动物；
    优选地，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴；
    优选地，所述哺乳动物为啮齿类动物；
    优选地，所述动物为鼠；
    优选地，所述动物选自成鼠；
    优选地，所述动物选自胎鼠；
    优选地，所述动物为基因人源化动物；
    优选地，所述基因为ACE2。
  12. 一种制备权利要求10所述的打靶载体的方法，包括以下步骤：
    将PCR扩增得到的产物片段5’同源臂、人ACE2 CDS和SV40 polyA使用搭桥PCR法PCR成连续片段5arm-hACE-SV40；
    所述PCR反应体系为：
    2×Phanta Max Buffer约为25μL；
    dNTP Mix约为1μL；
    10μM上游引物约为2μL；
    10μM下游引物约为2μL；
    DNA Polymerase约为1μL；
    H 2O补充至约为50μL；
    模板链5’同源臂、人ACE2 CDS、SV40 polyA片段各约20ng-200ng；
    优选地，所述PCR的反应程序为：
    PCR扩增反应条件约62-68℃起始，每个循环降约为0.2-0.8℃；
    优选地，扩增所述5’同源臂片段使用的引物包括与如SEQ ID NO:19所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:20所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物；
    优选地，扩增所述人源ACE2基因片段使用的引物包括与如SEQ ID NO:21所示的序列具有至少85％或至少90％或至少91％或至少92％或至 少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:22所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物；
    优选地，扩增所述SV40 polyA序列使用的引物包括与如SEQ ID NO:23所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:24所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物；
    优选地，所述方法还包括以下步骤：
    将5arm-hACE-SV40片段进行AgeI+MluI双酶切；3’同源臂片段进行AscI+HindIII双酶切后分别通过酶切连接的方法连接上去，从而得打靶载体；
    优选地，所述3’同源臂片段使用的引物包括与如SEQ ID NO:25所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的上游引物和与如SEQ ID NO:26所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的下游引物。
  13. 一种细胞株或细胞系的制备方法，所述方法中使用了权利要求7或8所述的引物组合；
    优选地，所述的方法包括使用了权利要求10所述的打靶载体；
    优选地，所述方法包括将人源目的基因导入动物细胞中，使得目的基因在动物细胞内表达人源目的基因的CDS；
    优选地，所述目的基因为ACE2；
    优选地，所述动物为哺乳动物；
    优选地，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴；
    优选地，所述动物为啮齿类动物；
    优选地，所述动物为鼠；
    优选地，所述动物选自成鼠；优选地，所述动物为鼠；
    优选地，所述动物选自胎鼠；
    优选地，所述动物为基因人源化动物；
    优选地，所述细胞为胚胎干细胞。
    优选地，所述制备方法包括以下步骤：
    (1)制备权利要求10所述的打靶载体；
    (2)将所述的打靶载体和连接有sgRNA的载体导入动物来源的胚胎干细胞中；
    (3)将步骤(2)中的胚胎干细胞培养成克隆，即得；
    优选地，所述sgRNA选自与如SEQ ID NO：1或SEQ ID NO：2所示的序列具有至少85％或至少90％或至少91％或至少92％或至少93％或至少94％或至少95％或至少96％或至少97％或至少98％或至少99％，或100％同一性的sgRNA；
    或优选地，所述动物为哺乳动物；
    优选地，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴；
    进一步优选地，所述哺乳动物为啮齿类动物；
    进一步优选地，所述啮齿类动物为鼠；
    优选地，所述动物选自成鼠；
    优选地，所述动物选自胎鼠；
    优选地，所述动物为基因人源化动物；
    优选地，所述基因为ACE2。
  14. 权利要求13所述的方法制备得到的细胞株或细胞系。
  15. 一种非人动物的制备方法，包括使用了权利要求7或8任一所述的引物组合；
    优选地，所述的方法包括使用了权利要求10所述的打靶载体；
    优选地，所述方法包括将权利要求14所述的细胞注入动物体内；
    优选地，所述动物为哺乳动物；
    优选地，所述动物选自猪、大鼠、小鼠、仓鼠、兔、猪、牛、鹿、绵羊、山羊、小鸡、猫、马、狗、猩猩、猴；
    进一步优选地，所述哺乳动物为啮齿类动物；
    进一步优选地，所述啮齿类动物为鼠；
    优选地，所述动物选自成鼠；
    优选地，所述动物选自胎鼠；
    优选地，所述动物为基因人源化动物；
    优选地，所述基因为ACE2。
  16. 一种非人动物或非人动物或其子孙的组织、体液、细胞、以及它们的破碎物或提取物，所述的非人动物是由权利要求15所述的方法制备的。
  17. 来源于权利要求15所述的方法得到的人源化动物模型或其后代在制造人类抗体，或者作为药理学、免疫学、微生物学和医学研究的模型系统中的应用，或在生产和利用动物实验疾病模型，用于病原学研究和/或用于开发新的诊断策略和/或治疗策略中的应用，或在筛选、验证、评价或研究ACE2基因功能、ACE2抗体、针对ACE2靶点的药物、药效研究方面的用途。
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