WO2010127474A1 - 乙型肝炎病毒耐阿德福韦变异病毒株及其应用 - Google Patents

乙型肝炎病毒耐阿德福韦变异病毒株及其应用 Download PDF

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WO2010127474A1
WO2010127474A1 PCT/CN2009/001165 CN2009001165W WO2010127474A1 WO 2010127474 A1 WO2010127474 A1 WO 2010127474A1 CN 2009001165 W CN2009001165 W CN 2009001165W WO 2010127474 A1 WO2010127474 A1 WO 2010127474A1
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rte218g
mutation
seq
hbv
sequence
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French (fr)
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魏来
杜绍财
刘丽君
汪江华
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Peking University Peoples Hospital
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Peking University Peoples Hospital
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Priority to EP09844226A priority Critical patent/EP2428564A4/en
Priority to US13/318,783 priority patent/US20120141977A1/en
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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
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    • C12N7/00—Viruses; Bacteriophages; Compositions thereof; Preparation or purification thereof
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    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
    • C12N9/10—Transferases (2.)
    • C12N9/12—Transferases (2.) transferring phosphorus containing groups, e.g. kinases (2.7)
    • C12N9/1241—Nucleotidyltransferases (2.7.7)
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
    • C12Q1/70—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving virus or bacteriophage
    • C12Q1/701—Specific hybridization probes
    • C12Q1/706—Specific hybridization probes for hepatitis
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
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    • C12N2730/00—Reverse transcribing DNA viruses
    • C12N2730/00011—Details
    • C12N2730/10011—Hepadnaviridae
    • C12N2730/10111—Orthohepadnavirus, e.g. hepatitis B virus
    • C12N2730/10122—New viral proteins or individual genes, new structural or functional aspects of known viral proteins or genes
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q2600/00—Oligonucleotides characterized by their use
    • C12Q2600/136—Screening for pharmacological compounds

Definitions

  • the invention relates to the field of medical biotechnology, in particular to a hepatitis B virus resistant to adefovir
  • the present invention also relates to its detection reagent and the application of the virus strain in drug resistance monitoring, cross-resistance analysis, drug screening and discovery of new drugs. Background technique
  • Adefovir dipivoxil is a prodrug of adenine phosphate compound adefovir (ADV), which can be rapidly hydrolyzed to ADV after oral administration to exert an antiviral effect.
  • ADV is a broad-spectrum antiviral drug that is a nucleoside reverse transcriptase inhibitor that exerts an antiviral effect by inhibiting HBV replication. Studies have confirmed that ADV has good efficacy and safety in patients with HBeAg-positive or HBeAg-negative chronic hepatitis B. It is now used as a first-line drug for antiviral treatment of chronic hepatitis B.
  • HBV DNA-resistant mutations can occur in ADV treatment, leading to ADV resistance.
  • ADV resistance mutations are rtN236T in the D region of HBV polymerase and rtA181V/T in the B region. In the early stage of ADV treatment, several mutations may occur or may occur alone, but as the course of treatment increases, rtA181V often occurs with rtN236T.
  • rtA181V corrected the change in amino acid polarity, so that after the rtN236T mutation, the polymerase fold was closer to the original state, which was beneficial to the replication of the resistant strain.
  • both in vivo and in vitro data suggest that the rtA181V variant is less sensitive to lamivudine than the rtN236T variant. This is most likely because the rtA181V variant is adjacent to lamivudine's rtLlSOM, so any occurrence of a mutation will have an ortho effect.
  • ADV is also commonly used in patients with previous lamivudine treatment failure.
  • Early 48-week and 96-week clinical trials suggest that both wild-type and YMDD mutant strains are sensitive to ADV, and HBV DNA declines exponentially after treatment, and patients are well tolerated. Therefore, the combination of the two drugs can more effectively inhibit the replication of the virus, but the rtL180M+M204V and rtN236T combination mutations in the polymerase region may also occur, which is resistant to lamivudine and ADV.
  • the object of the present invention is to find a novel HBV mutation site causing AV resistance and a corresponding HBV mutant virus strain, and provide a detection method and a detection kit for the novel mutation site, and provide an identification method and identification of the corresponding HBV mutant virus strain.
  • the present invention found that the rtE218G mutation, that is, the amino acid codon at position 218 of the HBV DNA polymerase region was mutated from GAG to GGG, which is a novel HBV gene mutation site associated with ADV resistance.
  • the results of in vitro phenotypic experiments showed that the rtE218G mutant strain was able to independently induce resistance to ADV, and its IC 50 was 5.5 times that of the wild virus strain.
  • the replication ability of the rtE218G mutant was reduced in vitro, which was approximately 87% of the wild strain.
  • the invention also provides the use of the rtE218G mutant strain in screening antiviral drugs. This mutant strain can be used for cross-resistance analysis and drug screening of other anti-HBV drugs.
  • a DNA fragment containing the rtE218G mutation site can also be further cloned into a vector by a person skilled in the art, and the vector can be further introduced into the corresponding host cell for ease of use
  • the invention also provides several methods for detecting the rtE218G mutation site and identifying a corresponding HBV mutant virus strain, including:
  • Reverse probe hybridization may be employed in which the probe is immobilized on a solid support, the labeled DNA fragment to be detected is hybridized thereto, and the unhybridized sequence is washed away to detect the hybridization result.
  • hybridization detection can be further carried out by the following two methods:
  • Reverse linear probe hybridization method Based on the principle of probe hybridization, a series of probes are designed to cover the high-risk region of mutation.
  • the S-series probes are directed to the wild-type sequence, and the R-series probes contain several common mutation sequences.
  • the probe can also be designed with a species-specific probe.
  • the probes are sequentially immobilized on the same hybrid membrane, and hybridized with the avidin-labeled PCR product under stringent conditions to detect the hybridization signal. The presence or absence of the mutation and the approximate location were determined based on the different hybridization bands.
  • the amplified biomarker-labeled HBV DNA product is hybridized with a specific oligonucleotide probe immobilized on a nylon membrane strip in parallel. After hybridization, the DNA that failed to hybridize is eluted from the test strip. Streptavidin labeled with a basic phosphatase is then added to bind to the labeled biotin on the hybridization product. Finally, BCIP/NBT color is added, and purple/brown appears to judge the result.
  • the process of forming heterologous hybrid molecules in the renaturation process due to the complementarity between two or more different polynucleotide chains is called hydridization.
  • the molecules in the hybrid are not from the same dimeric molecule. Because the temperature is easier to control than other denaturation methods, when the double-stranded nucleic acid is high At its denaturation temperature (Tin value), it de-spins into a single-stranded molecule; when the temperature falls below the Tm value, the single-stranded molecule is refolded into a double-stranded molecule according to the base pairing principle. Therefore, the change in temperature is usually used to cause nucleic acid hybridization in the process of denaturation and renaturation.
  • nucleic acid single strands of the nucleic acid molecule there is a complementary base sequence between the single strands of the nucleic acid molecule, and a stable double-stranded region is formed by the formation of a non-covalent bond between the base pairs, which is the basis for hybridization of the nucleic acid molecule.
  • the formation of hybrid molecules does not require that the base sequences of the two single strands be completely complementary. Therefore, nucleic acid single strands of different origins can form hybrid double strands with a certain degree of complementary sequence, and hybridization can be carried out in DNA and DNA. RNA and RNA or between RA and the two single strands of DNA.
  • one of the hybridization chains is first labeled in a detectable manner, and then hybridized with another nucleic acid (sample to be tested), and then the nucleic acid sequence to be tested is qualitatively or quantitatively detected. The presence or absence of the gene or the expression of the gene in the sample to be tested is analyzed.
  • Gene chips usually use a reverse hybridization method in which a plurality of probe molecules are spotted on a chip, and the nucleic acid target of the sample is labeled and hybridized with the chip. This has the advantage that thousands of targets or even whole genomes can be studied simultaneously as target sequences.
  • PCR-RFLP Polymerase chain reaction-restriction fragment length polymorphism
  • the HBV genotype reference strain sequence is selected from GenBank, and the mutagenic primer B2 (downstream 5'-TTG GTAATA GAG GTA AAA AGG TAC-3') is designed, and the primer and the rtE218G variant position are designed.
  • the points together constitute an cleavage site that can be recognized by the ⁇ « « 1 endonuclease.
  • B1 upstream 5, - GAG TGG GCC TCA GTC CGT TTC TC-3,
  • B2 amplify HBV DNA to obtain a 160 bp amplified fragment, which was digested with ⁇ ⁇ restriction endonuclease, and the rtE218G mutant was cut. Two fragments of 140 bp and 20 bp were inserted, while the wild strain could not be cut and maintained a 160 bp fragment.
  • LCR Ligase chain reaction
  • the basic principle of LCR is to rapidly perform DNA fragment amplification by ligating two adjacent oligonucleotide strands complementary to the template DNA under the action of DNA ligase.
  • DNA ligase ligates two adjacent oligonucleotide fragments complementary to the template; DNA strand.
  • the presence of a base mismatch at the linker of the two oligonucleotides prevents the ligation reaction from occurring. So through LCR, you can clearly distinguish between oligomerization Whether the nucleotide is fully complementary to the template DNA, detects a point mutation in the gene.
  • the program is: template DNA, DNA ligase, oligonucleotide primer under the corresponding reaction conditions, first heated to a certain temperature (94 95 ⁇ ) to denature DNA, double-stranded, and then cooled annealing (about 65 )), primer
  • the complementary template DNA binds and leaves a gap. If the adjacent oligonucleotide primer hybridizing with the target sequence is completely complementary to the target sequence, the DNA ligase can be ligated to close the gap, then the three steps of the LCR reaction (Degeneration-anneal-linkage) can be repeated, and the product of each ligation reaction can be used as a template in the next round of reactions, allowing more oligonucleotides to be ligated and amplified. If the target sequence at the junction is a little mutated, the primer cannot bind precisely to the target sequence, and the spatial structure of the nucleotide near the gap changes, the ligation reaction cannot proceed, and the ligation product cannot be formed.
  • LCR primers are two pairs of complementary primers, the primer length is 20 ⁇ 26, to ensure the specific binding of the primer to the target sequence, LCR recognition point mutation specificity is higher than PCR, its specificity depends first on the primer and template The specific binding, followed by the specificity of the thermostable ligase.
  • the LCR ligation reaction temperature is close to the melting temperature (Tm) of the oligodeoxynucleotide, thus the specificity of identifying single nucleotide mismatches is extremely high.
  • LCR amplification efficiency of LCR is comparable to that of PCR.
  • LCR is only used in two temperature cycles with heat-resistant ligase, 94 °Cmin denaturation and 65 °C renaturation and connection, cycle about 30 times.
  • the detection of its products is also more convenient and sensitive.
  • the method is mainly used for the research and detection of point mutations, the detection of microbial pathogens and directed mutagenesis, etc. It can also be used for the diagnosis of single-base genetic disease polymorphisms and single-base genetic diseases, and the identification of microorganisms. Point mutation studies of oncogenes, etc.
  • ligase chain reaction method two pairs of adjacent oligonucleotide strands complementary to the DNA sequence of the HBV mutant were designed for the rtE218G mutation, and one of the oligonucleotide strands in each pair was adjacent to the other and adjacent The base of the end of the terminus is complementary to the base of the rtE218G mutation site.
  • the ligase chain reaction was carried out using HBV DNA to be tested as a template, and the ligation product was detected to determine whether or not the rtE218G mutation occurred.
  • Nucleotide sequencing method The target DNA fragment is amplified by PCR, and the DNA fragment to be detected is directly determined by nucleotide sequence to determine whether it is a mutant strain.
  • the PCR product can also be cloned first, and then multiple colonies are picked for sequencing analysis.
  • Sequence-specific primer method According to the mutation site, synthetic sequence-specific primers were designed. The target DNA fragment is amplified by PCR, and since the wild or mutated sequence is only amplified by complementary binding to the corresponding primer, it is judged whether or not it is a mutant by detecting the presence or absence of the specific amplification product. Preferably, the probe is subjected to quantitative PCR.
  • the specific primer F1 5
  • F2 5 '-TTG GTA ATA GAG GTA AAA AGG TTT C-3 '
  • the probe FAM-5'-TAG TGC CAT TTG TTC AGT GGT TCG TAG-3'-TAMRA, for quantitative PCR detection, only the mutant strain can detect specific amplification.
  • PCR-SSCP Single Strand Conformation Polymorphism Analysis of Polymerase Chain Reaction Products
  • PCR-SSCP analysis The basic procedure for PCR-SSCP analysis is: First, a specific target sequence is PCR-amplified, and then the amplified product is denatured into a single strand for non-denaturing polyacrylamide gel electrophoresis.
  • the mobility of the DNA single strand is related to the length of the DNA strand, and more importantly depends on the conformation formed by the DNA single strand.
  • DNA single strands Under non-denaturing conditions, DNA single strands can fold themselves to form a conformation with a certain spatial structure. This conformation is determined by the single-stranded base of DNA, and its stability is maintained by the interaction of local sequences within the molecule (mainly hydrogen bonds).
  • the PCR-SSCP analysis technique is a DNA single-strand gel electrophoresis technique that detects genetic variation based on changes in electrophoretic mobility of a single-stranded DNA single strand of different conformations in a neutral polyacrylamide gel. This technology is widely used in the detection of oncogenes and anti-cancer gene mutations, pathogenic gene analysis of genetic diseases, and gene diagnosis, gene mapping and the like.
  • primers or nucleosides may be labeled with an isotope or fluorescein in PCR amplification, or may be stained with silver stain or ethidium bromide after electrophoresis to display the results.
  • the most common radioisotope PCR-SSCP method will be highlighted here.
  • PCR amplification is carried out by using ⁇ -32P-ATP-labeled primer or directly adding a-32P-dCTP to the PCR reaction system, so that the amplified product carries an isotope label and then expands.
  • the product was denatured into a single strand for non-denaturing polyacrylamide gel electrophoresis, and the results were shown by autoradiography.
  • the use of primer labeling or base incorporation to allow PCR amplification products to carry isotope labels can increase product signal orders of magnitude. Compared with the two, the former has strong economic and amplification specificity, and is mostly used for detection and screening of large samples. The latter is easy to operate and suitable for general laboratory development, and can be used for detection and screening of small samples or large samples.
  • the invention further provides for detecting the rtE218G mutation site and identifying the corresponding HBV mutant virus strain.
  • Reagents including various primers and/or probes.
  • the detection reagent and other necessary reagents may further be assembled into a detection kit for convenient use.
  • the above primers and restriction enzymes are composed of
  • a PCR-RFLP detection kit or a site-specific primer and a fluorescent probe to form a fluorescent quantitative PCR test kit and the like.
  • the detection reagent can be selected from:
  • a primer pair which specifically amplifies a nucleotide sequence including a rtE218G mutation site; or b, an amplification product thereof including a rtE218G mutation site and the site and the two-end or one-end sequence may constitute a restriction Endonuclease recognition site;
  • sequence-specific primer pairs one of which binds specifically to a nucleotide sequence comprising the rtE218G mutation site
  • an oligonucleotide sequence for ligase chain reaction according to the ligase chain reaction method, two pairs of adjacent oligonucleotide strands complementary to the DNA sequence of the HBV mutant strain are designed for the rtE218G mutation, in each pair One oligonucleotide strand is adjacent to the other, and the base of the adjacent end is complementary to the base of the rtE218G mutation site.
  • the above kit comprises the primer pair described in 1), it further comprises the restriction endonuclease; when comprising the sequence-specific primer described in 2), it further comprises a specific binding to the sequence of interest. Probe.
  • the method for detecting the HBV rtE218G mutation and the method for identifying the corresponding HBV mutant virus strain can be used only in laboratory studies, or the HBV rtE218G mutation site and the corresponding HBV suitable for drug resistance monitoring and new drug development can be detected or identified only by the above method.
  • the HBV rtE218G mutation can also be used for clinical guidance.
  • the invention also provides a method for clinically guiding medication, comprising detecting a mutation of HBV rtE218G, and selecting a medication according to the detection result.
  • the detection of the HBV rtE218G mutation can be preferably carried out using the above reagents or kits.
  • Figure 1 shows that each plasmid was digested with endonuclease and III to produce 1.2-fold HBV full-length gene (about 3.8 kb) and PUC18 vector fragment (about 2.8 kb);
  • Figure 2 is a mutated plasmid sequencing map to verify the correct introduction of the mutagenesis site, wherein the mutagenic nucleotide position is indicated by the arrow, and the underline is the codon encoding the corresponding mutagenized amino acid;
  • Figure 3 shows the results of Southern blotting, showing the inhibitory effects of different concentrations of ADV on wild-type and rtE218G mutant HBV replication intermediates
  • Figure 4 is a dose-response curve obtained by performing gray value analysis based on the results of Southern blotting, showing that ADV has different inhibitory effects on wild-type strain and rtE218G mutant strain, and the IC50 of the mutant strain is 5.5 times that of the wild-type strain.
  • Example 1 The technical means used in the examples are conventional technical means well known to those skilled in the art unless otherwise specified.
  • Example 1 The technical means used in the examples are conventional technical means well known to those skilled in the art unless otherwise specified.
  • Serum specimens from patients with chronic hepatitis B who were not treated with ADV were stored at -3 (TC standby.
  • the plasmid PUC-HBV 1.2WT contains 1.2 copies of HBV DNA (genotype C, Genbank introduction number AY518556), which is preserved by the Institute of Liver Diseases, Peking University People's Hospital.
  • the pGEM-T Easy vector kit for A-T clones was purchased from Promega, USA, and the DH5a competent cells were purchased from Dingguo Biotechnology.
  • Protease K, Poly(A), dNTPs, glycogen were purchased from Boehringer Mannheim (BM), X-gal, IPTG were purchased from Promega, USA, and agarose, diethyl pyrocarbonate (DEPC) was purchased from Fluca. Tryptone and yeast extracts were purchased from Oxid Co., phenol was purchased from Invitrogen, DMEM medium, fetal bovine serum was purchased from GIBCO, nitrophenol pNPP was purchased from Sigma, and other biochemical reagents were domestic analytical reagents.
  • Plasmid Mega Kit is a product of Qiagen, Germany.
  • High-efficiency eukaryotic transfection reagent VigoFect is purchased from Weigras Biotechnology (Beijing) Co., Ltd., HBsAg and HBeAg are measured using ARCHITECT® microparticle chemiluminescence detection kit ( Abbott, USA) HBV DNA Fluorescence Quantitative PCR Kit was purchased from Shenzhen Piki Bioengineering Co., Ltd.
  • the digoxin probe labeling kit, anti-digoxigenin antibody and CPD Star kit were purchased from Roche, Germany.
  • High-fidelity DNA polymerase was purchased from Beijing Quanjin Biotechnology Co., Ltd.
  • T4 DNA ligase was purchased from Promega, USA, and various restriction enzymes were purchased from American ⁇ .
  • the human hepatoma cell line HepG2 was purchased from the Institute of Cell Biology, Chinese Academy of Sciences, and stored in liquid nitrogen. After resuscitation, it was cultured in a 37 ° C, 5% CO 2 incubator, using high glucose DMEM medium containing 10% fetal bovine serum. to cultivate.
  • Adefovir dipivoxil lyophilized powder, stored at 4 ° C, dissolved in PBS, stored at -20 ° C.
  • the high-speed cryogenic centrifuge CF15R is HITACHI
  • the desktop high-speed centrifuge Micromax is the German IEC company
  • the PTC-100 Peltier Thermal Cycler is the American MJ Research company
  • the gel automatic imaging system GEL Doc2000 is the Bio-Rad product.
  • the constant temperature incubator is the product of Revco Company of the United States
  • the constant temperature air bath shaker is the product of Harbin Dongming Medical Instrument Factory
  • the carbon dioxide incubator 3111 is the product of Forma Scientific
  • the ultra clean workbench is the product of Beijing Changping Great Wall Air Purification Engineering Company.
  • the MLS-3000 is a product of SANYO
  • the Reader 230s is a product of DRGAnon Teloiika
  • the LightCycler II is a Roche product.
  • the primers used in the detection method were designed according to the HBV genotype sequences in GenBank, and the mutation sites were introduced at corresponding positions; the remaining primers were designed according to the HBV sequence in PUC-HBV1.2WT. All primers were synthesized by Beijing Sanbo Yuanzhi Biotechnology Company. The sequencing work was completed by Beijing Nosai Genomic Research Center Co., Ltd. The sequencing reagent was ABI BigDye3.1 and the sequencing instrument was ABI 3730XL.
  • ADV-resistant chronic hepatitis B patient serum samples are amplified by polymerase region, and the PCR products are Cloning and sequencing.
  • the viral DNA in the serum samples was extracted by the protease K-phenol chloroform method, dissolved in 30 ⁇ l of hydrazine, and stored at -80 °C until use. '
  • HBV DNA 3 ⁇ ⁇ extracted from the patient's serum was used as a template to BSE (upstream: 5,-CTC GTG GTG GAC TTC TCT CA-3') and PO (downstream: 5,-GGG TTG CGT CAG CAAACA).
  • CTT G-3' is a primer with amplification conditions of 94 ⁇ 300 sec, 94 ° C for 30 sec, 55 ° C for 30 sec, 72 ° C for 45 sec, 30 cycles. Take 3 ⁇ 1 of the first PCR product, and then use Hinfed (upstream: 5,-GAG TGG GCC TCA GTC CGT TTC TC-3 ') and SSG (downstream: 5,- ACA TAT CCC ATG AAG TTAAG-3 ') as primers.
  • connection system includes:
  • a suitable volume of the conversion product was applied to an LB plate (containing 1 mol/1 IPTG 4 ⁇ l, 20 mg/ml X-gal 40 ⁇ l) containing 100 mg/ml ampicillin, 37. C was inverted and cultured overnight.
  • the reaction system contains:
  • the enzyme was digested at 37 ° C for 1 hour. 1.0% agarose gel electrophoresis, EB staining, observation under UV light. It is judged whether or not the HBV gene is inserted according to the length of the inserted fragment.
  • PCR-mediated site-directed mutagenesis was used to construct the mutagenized plasmid' plasmid PUC-HBV 1.2WT containing 1.2 copies of HBV DNA (genotype C, Genbanl introduction number AY518556). The first round of PCR was preceded by PUC-HBV1. 2WT 2ng as a template, using two pairs of primers P1A-2 (upstream: 5, - GAACATCGCATCAGGACTCCTAGGACCCCTG-3') and E218-3 (under
  • GCATAAAGGGACCCAAG-3' GCATAAAGGGACCCAAG-3'
  • E218-P1 upstream: 5'-CAACATCTTGGGTCCCTTT ATGC-3'
  • P2A downstream: 5,-GGCATTAAAGCAGGATATCCAC-3,
  • the amplification conditions were 94 ° C 300 seconds, 94 ° C 45 seconds, 55 ° C 45 seconds, 72 ⁇ 60 seconds, after 35 cycles, 72 ⁇ extended for 7 minutes.
  • a fragment A of 680 bp in size and a fragment of 287 bp in size were obtained, respectively. Fragments A and B were purified and recovered by a gel recovery purification kit (Qiagen, Germany).
  • the positive clone and plasmid pUC-HBVL2WT were digested with restriction endonucleases o?RV and ⁇ vr ll.
  • rtE218G mutagenesis plasmid PUC-HBV1.2-E218G (SEQ ID NO. 20) was obtained.
  • the strain containing the mutagenized plasmid was in May 2009 26 ⁇ is deposited in the General Microbiology Center of China Microbial Culture Collection Management Committee (Address: No. 3, Datun Road, Chaoyang District, Beijing, China, Institute of Microbiology, Chinese Academy of Sciences, Zip Code 100101).
  • the classification is Escherichia coH ⁇ PUC-HBV1.2-E218G, the accession number is CGMCC No.3079.
  • hepatoma cell line HepG2 After resuscitation of human hepatoma cell line HepG2, monolayer adherent cells were grown in DMEM medium containing 10% fetal bovine serum at 37 ° C under 5% C0 2 incubator, 1:3 every 3 to 5 days. Passage 1 time. Twenty-four hours prior to transfection, appropriate cells were inoculated (about 2 x 105 per well in a 6-well plate). The cell density at the time of transfection is preferably 40 to 60% (80 to 90%). One hour before transfection, fresh whole medium (2 ml per well) was replaced and cultured at 37 V, 5% CO 2 .
  • the medium was changed, and ADV was added at a final concentration of 0, 0.01, 0.1, 1, 5, 10, and 20 ⁇ , respectively, and the medium was changed and the anti-HBV drug/ADV was added every other day.
  • the cells were harvested in 8 days.
  • the cell culture supernatant was treated with lOO g/ml DNase I at 37 °C for 1 hour to digest the remaining transfected plasmid.
  • Viral DNA detection was performed on a Light Cycler II automated fluorescence quantitative PCR machine (Roche, USA) using the HBV DNA quantitative PCR assay kit, sample processing and amplification according to the product instructions.
  • HBsAg and HBeAg were measured using the ARCHITECT® Microparticle Chemiluminescence Detection Kit (Abbott, USA). The procedure was calculated according to the instructions. HBsAg is expressed as IU/ml and HBeAg is expressed as S/CO value.
  • reaction primer upstream Dl, 5 '-CCGGAAAGCTTGAGCTCTTCTTTTTCAC CTCTGCCTAATCA-3'; downstream D2, 5 '-CCGGAAAGCTTGAGCTCTTCAAAAAG TTGCATGGTGCTGG-3.
  • the reaction conditions are: pre-denaturation at 94 °C for 2 minutes, 94 °C for 30 seconds, 55 °C 30 Seconds, 72 ° C for 2 minutes, a total of 35 cycles, the 11th cycle begins with an increase of 20 seconds per cycle extension, and finally extends at 72 ° C for 7 minutes.
  • the PCR product was ⁇ , and ⁇ 6 x loading buffer was added, 4 ⁇ l ⁇ 2 0, subjected to 1.0% agarose gel electrophoresis, stained with 0.5 g/ml EB, and observed under ultraviolet light. Note that the expected length of the product is slow due to the slower electrophoresis of the digoxin-labeled dUTP fragment, and the electrophoresis results show that the fragment size is slightly larger than 3.2 kb.
  • the purified PCR product was recovered using a Qiagen gel recovery purification kit and quantified as compared to a standard amount of probe.
  • the DNase I digestion reaction was terminated by the addition of EDTA at a final concentration of 25 mmol/L.
  • the final concentration was 0.5 mg/ml proteinase K and 1% SDS, and cleavage was carried out at 60 ° C for 1 hour.
  • Phenol: chloroform: isoamyl alcohol (25: 24: 1 , V/V) was extracted twice.
  • the supernatant was added to 2.5 volumes of absolute ethanol, 0.25 volume of 10 mol/L ammonium acetate, ⁇ (20 mg/ml) glycogen, and precipitated at -20 ° C overnight. Centrifuge at 14000 rpm for 15 minutes at 4 ° C and aspirate the supernatant.
  • HBV DNA was dissolved in TE ⁇ containing 2 ( ⁇ g/ml RNase A in TE).
  • the HBV replication intermediate in the extracted cytoplasm was subjected to 1.0% agarose electrophoresis. After electrophoresis, denaturing in a 5 times gel volume denaturing solution (0.5 mol/L NaOH, 1.5 mol/L NaCl) on a decolorizing shaker at room temperature for 45 min, and the gel was simply rinsed with distilled water and then changed to about 5 x volume.
  • the neutralized solution (lmol/L Tris-HCl, pH 7.4, 1.5 mol L NaCl) was neutralized twice, each time neutralized for 30 min.
  • Stop electrophoresis mark the position of the gel well with a pencil, and wash it in 5XSSC to remove the agar fragments.
  • the nylon membrane was taken out, the liquid was drained, placed on a paper towel, and naturally dried at room temperature for 30 minutes.
  • One side of the nylon membrane carrying the DNA was exposed to ultraviolet light, and 100 mJ/cm 2 was subjected to ultraviolet crosslinking fixation.
  • Fixed nylon membrane The membrane floated on the 5xSSC level and was completely infiltrated from bottom to top for 2 minutes.
  • the infiltrated membrane was placed in a hybridization flask, and a prehybridization solution DIG Easy Hyb preheated to 42 ° C was added to a filter of ⁇ 10 ml/100 cm 2 per square centimeter of filter. Prehybridization was carried out for 30 min in a 42 °C hybridization box.
  • the prehybridization solution was poured out, and the hybridized Dig High Hyb (3.5 ml/100 cm2) pre-warmed at 42 °C was added to the hybridization flask, and the digoxigenin-labeled HBV was added at a final concentration of 25 ng/ml which was denatured at 100 ° C for 5 minutes. Genomic probes.
  • the hybridization reaction was hybridized overnight in a 42 °C hybridization box.
  • the hybridization membrane was taken out and placed in a 15 cm culture dish, and about 200 ml of 2xSSC and 0.1% SDS solution was added thereto, and gently shaken at room temperature for 5 min x 2 on a decolorizing shaker.
  • the blocking solution was removed, and an anti-digoxigenin antibody diluted 1:5000 in lx blocking solution was added and incubated for 30 min at room temperature.
  • the membrane was washed with 200 ml of maleic acid wash (0.3% Tween-20 in lx maleic acid buffer) and the membrane was washed twice at room temperature for 15 min. Rinse in assay buffer (0.1 M Tris-HCl, O.lM NaCl, pH 9.5) for 5 min.
  • CSPD Dilute CSPD (25 mmol L, 11.6 mg/ml) with 1:200 in assay buffer, blot the liquid on the nylon membrane with a paper towel, place on the plastic wrap, and add the diluted CSPD to the nylon in a volume of 1 ml/100 cm 2 . Spread on the film and spread evenly.
  • the nylon membrane was clamped with plastic wrap. After 5 min at room temperature, excess CSPD was blotted with filter paper and incubated for 10 min at 37 °C.
  • X-ray film and nylon film wrapped with plastic wrap were pressed into the cassette in a dark room and exposed for 15-20 min. The X-ray film was washed, and the relative gray value of the HBV replication intermediate in the transfected cells was determined by image analysis software Quantity One.
  • the experimental results between the groups can be directly compared.
  • the specific testing process is as follows: ' The ⁇ cell culture supernatant was heat-inactivated at 65 ° C for 30 minutes to inactivate endogenous alkaline phosphatase, 14,000 X g, and centrifuged for 2 minutes to remove cell debris. (The supernatant can be stored at -20 ° C). Transfer 50 ⁇ l of the treated cell culture supernatant to a 96-well plate, equilibrate to 37 ° C, set up the duplicate well, and then add 45 ⁇ l of 2 x SEAP buffer (20 mmol/l homoarginine, 1 mmol) equilibrated to 37 ° C.
  • the wild-type HBV replication plasmid PUC-HBV1.2WT was used as a template to construct the expression plasmid of rtE218G mutant, which was named PUC-HBV1.2-E218G.
  • the mutagenized plasmid was identified by double digestion with coR I and III. The results are shown in Figure 1. The sequencing of the mutation was verified by sequencing. The sequencing results are shown in Figure 2. Compared with the wild type, the rtE218G mutation occurred in the polymerase region. GAG became GGG.
  • the wild type and the above mutagenized plasmid were transiently transfected into HepG2 cells for 96 hours, and the cells and the culture supernatant were collected, and the transfection efficiency was corrected by the exogenous alkaline phosphatase level expressed by the plasmid pSEAP2, and wild type and mutagen type were detected.
  • HBeAg and HBsAg were present in the supernatant of HBV expression plasmid transfection group, and the viral DNA copy number reached (4,52 ⁇ 0.83) 10 5 (copy/ml) and (4.25 ⁇ 0.14) 10 5 (copies/ml) It is suggested that the mutagenesis plasmid can transfect HepG2 cells to establish the replication state of HBV and express viral antigen and secrete virus particles.
  • Wild-type and mutagenized plasmids were transiently transfected into HepG2 cells 96 hours later, and the levels of HBV DNA and cytoplasmic HBV replication intermediates in the supernatant were determined. The results showed that the virus replication ability of the mutant strain was lower than that of the wild strain, which was 87% of the wild strain.
  • PCR-RFLP Polymerase chain reaction-restriction fragment length polymorphism
  • the amplification conditions were: 94 V 60 seconds, 94 ° C 30 seconds, 60 °C 45 seconds, 35 cycles, the amplified fragment length is 160bp. Detection by ⁇ « ⁇ restriction endonuclease analysis.
  • the enzyme digestion system l O x enzyme buffer ⁇ ⁇ ⁇ , enzyme 5U, PCR product 2-4 ⁇ ⁇ , add DEPC water to a total volume of 10 ⁇ 1 . Digestion conditions: 37V, 2 ⁇ 4 hours. As a result, the mutant strain was cut into two fragments of 140 bp and 20 bp, and the wild strain was not cut, and the 160 bp fragment was maintained.
  • the outer primer is: upstream SA: 5 '-TCG TGT TACAGGCGGGGT TT-3', downstream P0: 5, -GGG TTG CGT CAG CAAACA CTT G-3'; inner primer is, upstream BSE: 5 '-CTC GTG GTG GAC TTC TCT CA-3 % Downstream 1162: 5'-TTG CCG GGC AAC GGG GTAAAG-3,.
  • the amplification conditions were 94 °C for 300 seconds, 94 ⁇ 30 seconds, 55 °C for 30 seconds, 72 °C for 45 seconds, and 35 cycles.
  • the first PCR product diluted 3 ⁇ l 1 100 was taken as the second template.
  • the PCR product of 910 bp size can be directly determined by nucleotide sequence; A-T cloning can also be performed first, and then multiple colonies are selected for sequencing analysis. Finally, based on the sequencing results, it is directly judged whether it is a mutant strain.
  • Sequence-specific primer method According to the mutation site, design synthetic sequence-specific primer F1 :5,-GAG TGG GCC TCA GTC CGT TTC TC-3,, F2: 5' -TTG GTA ATA GAG GTA AAA AGG TTT C-3' , Fluorescent Labeled Probe: FAM-5,-TAG TGC CAT TTG TTC AGT GGT TCG TAG-TAMRA -3'.
  • the target DNA fragment was amplified by real-time PCR, and the amplification conditions were 42 ° C for 120 seconds, 94 ° C for 120 seconds, then 94 ° C for 10 seconds, 65 ° C for 20 seconds, and 40 cycles. The results indicate that only the mutant strain can be specifically amplified, since only the sequence in which the rtE218G mutation has occurred can be complementary to the primer.
  • the present invention discloses a HBV rtE218G mutation site which has been found to be involved in adefovir resistance.
  • the present invention further provides methods and related reagents for detecting the HE218G mutation site. By testing the site of variation, clinical drugs are screened, as well as screening for new drugs.
  • the microorganism (strain) was 2Q ⁇ 39 On May 26 received by the Collection, and were registered.

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Description

乙型肝炎病毒耐阿德福韦变异病毒株及其应用 技术领域
本发明涉及医药生物技术领域, 具体涉及一株耐阿德福韦的乙型肝炎病毒
( HBV ) 变异株, 本发明还涉及其检测试剂以及该病毒株在耐药性监测, 交叉耐 药性分析、 药物筛选和新药物的发现等多方面的应用。 背景技术
阿德福韦酯是腺嘌呤磷酸酯化合物阿德福韦 (ADV ) 的前药, 口服后可迅速 水解为 ADV而发挥抗病毒作用。 ADV是广谱抗病毒药物, 为核苷类病毒逆转录 酶抑制剂,通过抑制 HBV的复制而发挥抗病毒作用。研究已证实, ADV对 HBeAg 阳性或 HBeAg阴性的慢性乙型肝炎患者均有很好的疗效和安全性。现巳作为一线 药物应用于慢性乙型肝炎的抗病毒治疗。
与其他核苷类药物一样, ADV治疗中, 也会发生 HBV DNA耐药突变, 从而 导致 ADV耐药。 研究表明, ADV治疗慢性乙型肝炎患者过程中, 第 1-5年的耐 药突变发生率分别为 0%、 3%、 11%、 18%和 29%。
最常见的 ADV耐 突变是 HBV聚合酶 D区的 rtN236T和 B区的 rtA181V/T。 在 ADV治疗初期, 几种突变可以伴随发生, 也可单独出现, 但随着疗程的增加, rtA181V常伴随 rtN236T而出现。在体外药敏试验中,与野生株病毒相比, rtN236T 变异病毒株对 ADV的敏感性下降了 3.9至 13.8倍, 而 rtA181V变异株下降了 2.5 至 3.0倍。 巳有多项研究指出, rtN236T的出现改变了复制催化活性区内氨基酸的 极性, 使得 HBV聚合酶的折叠发生了变化, 因此在复制阶段不利于其与底物的结 合, 从而导致复制过程受阻碍。 而 rtA181V的出现, 在一定程度上校正了氨基酸 极性上的变化, 使得发生 rtN236T突变后, 聚合酶折叠更接近于原来状态, 有利 于耐药性变异病毒株的复制传代。 此外, 体内试验和体外试验的数据均提示, rtA181V变异对拉米夫定的敏感性不及 rtN236T 变异。 这很可能是因为 rtA181V 变异与拉米夫定的 rtLlSOM相毗邻, 所以任何一种变异的发生都会对其产生邻位 效应。
突变 rtN236T和 rtA181V对 HBeAg阴性和阳性患者的影响不完全相同。 ADV 耐药现象在低病毒血症且 HBeAg阳性患者中的发生率相当低,耐药的发生也部分 体现在 ALT的升高上。 对于 HBeAg阴性的患者来说, ADV治疗 48 周后停药, 治疗获益常在停药 1 ~ 2年后消失。 但若继续用药直至 144周, 患者在治疗 48周 时所获得的病毒学、 血清生化及组织学等各方面改善, 将被保留且进一步好转。 期间耐药发生率很低, 且负面作用与初始的 48周治疗时相似。
目前, ADV也常用于前期拉米夫定治疗失效的患者。 早期 48周及 96周临床 试验均提示, 无论是野生型还是 YMDD突变型病毒株, 均对 ADV敏感, 治疗后 HBV DNA 下降呈指数趋势, 且患者的耐受性良好。 故两种药物联合应用更加有 效地抑制了病毒的复制, 但也可能发生聚合酶区的 rtL180M+M204V 和 rtN236T 联合突变, 对拉米夫定和 ADV产生双重耐药。 尽管研究表明, 拉米夫定耐药株对 ADV敏感, 但对 HBV本身来说, 三种变异联合增加了对 ADV的耐药水平, 与 rtN236T单突变相比, 对 ADV的敏感性下降了 2倍。 在分子水平, 联合突变导致 底物结合位点更难与阿德福韦结合, 因此进一步降低了对 ADV的敏感性。
迄今为止, 学者们发现不但 HBV聚合酶基因区的 rtA181V、 rtN236T变异可 引起 ADV相关耐药,其他许多与 ADV相关的突变,例如 rtI233V、 rtS85A> rtS85P、 rtS119A、 rtH133L、 rtV214A、 rtH234Q、 rtP237H和 rtN238D等, 也可能与 ADV 耐药有关。 然而, 仍有许多慢性乙型肝炎患者, 在 ADV治疗中出现临床耐药, 却 检测不出已知变异位点的存在。 故 ADV相关 HBV突变的研究还需要进一步的探 索。 发明内容
本发明的目的是, 找到引起 A V耐药的 HBV新变异位点和相应的 HBV突 变病毒株, 提供此新变异位点的检测方法和检测试剂盒, 提供相应 HBV突变病毒 株的鉴定方法和鉴定试剂盒,以及此新变异位点和相应的 HBV突变病毒株在筛选 抗 HBV药物, 监测耐药突变等方面的应用。
本发明发现 rtE218G突变, 即 HBV DNA聚合酶区 218位的氨基酸密码子由 GAG突变为 GGG, 该突变是与 ADV耐药相关的新的 HBV基因突变位点。 体外 表型实验结果显示, rtE218G突变病毒株能够独立引起对 ADV的耐药, 其 IC50是 野生病毒株的 5.5倍。 rtE218G突变株在体外的复制能力有所降低, 大约是野生株 的 87%。 本发明还提供 rtE218G突变株在筛选抗病毒药物中的应用。 可以利用该突变 株对其他抗 HBV药物进行交叉耐药性分析和用药筛选。本领域技术人员还可以进 一步将含有 rtE218G突变位点的 DNA片段克隆到载体中 ,并且可以进一步将所述 载体导入相应的宿主细胞中, 以便于使用和保存。
本发明还提供几种检测 rtE218G突变位点和鉴定相应 HBV突变病毒株的方 法, 包括:
1、 特异性探针杂交法: 用针对 rtE218G突变位点的探针与待检 HBV DNA片 段进行杂交, 通过检测杂交结果, 判断是否发生了 rtE218G突变。 可以采用反向 探针杂交法, 即将所述探针固定在固相载体上, 将带有标记的待检 DNA片段与之 杂交, 洗掉未杂交的序列, 进而检测杂交结果。 按照这种原理, 可进一步采用以 下两种方法进行杂交检测:
1 )反向线性探针杂交法: 基于探针杂交原理, 先设计合成一系列探针, 覆盖 突变高发区, 其中 S系列探针针对野生株序列, R系列探针含数个有常见突变序 列的探针, 还可以设计一个有种属特异性的探针, 将这一系列探针顺次固定于同 一杂交膜上, 在严格条件下与亲和素标记的 PCR产物杂交, 检测杂交信号, 根据 不同杂交带谱判定出突变有无及大致位置。 基于反向杂交的原理, 扩增后的被生 物素标记的 HBV DNA产物, 与平行线形式固定在尼龙膜检测条上的特异性寡核 苷酸探针杂交。 杂交后, 未能杂交的 DNA从检测条上被洗脱。 随后加入标记有碱 性磷酸酶的链霉亲和素, 与杂交产物上标记的生物素结合。 最后加入 BCIP/NBT 显色, 显现紫色 /棕色, 从而判断结果。
2 )基因芯片法: 利用杂交的原理, 即 DNA根据碱基配对原则, 在常温下和 中性条件下形成双链 DNA分子, 但在高温、 碱性或有机溶剂等条件下, 双螺旋之 间的氢键断裂, 双螺旋解开, 形成单链分子(称为 DNA ¾性, DNA变性时的温 度称 Tm值)。 变性的 DNA黏度下降, 沉降速度增加, 浮力上升, 紫外吸收增加。 当消除变性条件后,变性 DNA两条互补链可以重新结合,恢复原来的双螺旋结构, 这一过程称为复性。 复性后 DNA, 其理化性质能得到恢复。 利用 DNA这一重要 理化特性, 将两个以上不同来源的多核苷酸链之间由于互补性而使它们在复性过 程中形成异源杂合分子的过程称为杂交 (hydridization )。 杂交体中的分子不是来 自同一个二聚体分子。 由于温度比其他变性方法更容易控制, 当双链的核酸在高 于其变性温度 (Tin值)时, 解螺旋成单链分子; 当温度降到低于 Tm值时, 单链 分子根据碱基的配对原则再度复性成双链分子。 因此通常利用温度的变化使 DNA 在变性和复性的过程中进行核酸杂交。
核酸分子单链之间有互补的碱基顺序, 通过碱基对之间非共价键的形成即出 现稳定的双链区, 这是核酸分子杂交的基础。 杂交分子的形成并不要求两条单链 的碱基顺序完全互补, 所以不同来源的核酸单链彼此之间只要有一定程度的互补 序列就可以形成杂交双链, 分子杂交可在 DNA与 DNA、 RNA与 RNA或 R A与 DNA的两条单链之间。 利用分子杂交这一特性, 先将杂交链中的一条用某种可以 检测的方式进行标记, 再与另一种核酸 (待测样本)进行分子杂交, 然后对待测核酸 序列进行定性或定量检测, 分析待测样本中是否存在该基因或该基因的表达有无 变化。 基因芯片通常采用反向杂交方法, 即将多个探针分子点在芯片上, 样本的 核酸靶标进行标记后与芯片进行杂交。 这样的优点是同时可以研究成千上万的靶 标甚至全基因组作为靶序列。
2、 聚合酶链式反应一限制性片段长度多态性 (PCR— RFLP ) 分析技术: 原 理为采用 PCR扩增目的 DNA片段,然后将待检测的 DNA片段用限制性内切酶酶 切, 限制性内切酶识别并切割特异的序列, 然后将酶切后的产物进行电泳, 再由 限制酶图谱分析此段序列的特异酶切位点, 借由片段的多样性来比对不同来源基 因序列的差异性。 这里 rtE218G突变核苷酸包含于所述限制性内切酶的识别序列 中。 在本发明的一个实施例中, 从 GenBank中选取 HBV各基因型参考株序列, 设计诱变引物 B2 (下游 5'-TTG GTAATA GAG GTA AAA AGG TAC-3' ), 该引物 与 rtE218G的变异位点共同构成可被 ^«« 1内切酶识别的酶切位点。 应用 B1 (上 游 5,- GAG TGG GCC TCA GTC CGT TTC TC-3,), 与 B2 , 扩增 HBV DNA, 得到 160bp扩增片段, 再用 α Ι限制性内切酶消化, rtE218G变异株被切成 140bp和 20bp两个片段, 而野生株不能被 切开, 保持 160bp的片段。
3、 连接酶链反应 (Ligase chain reaction, LCR), 也是一种 DNA体外扩增和检 测技术, 主要用于点突变的检测。 LCR的基本原理是在 DNA连接酶的作用下, 通过连接与模板 DNA互补的两个相邻寡核苷酸链 ,快速进行 DNA片段扩增。 DNA 连接酶可将与模板; DNA链互补的两条毗邻寡核苷酸片段连接起来。两条寡核苷酸 链接头处存在碱基错配则阻止连接反应的发生。 所以通过 LCR, 可明确区分寡聚 核苷酸是否与模板 DNA完全互补,检测基因点突变。其程序为:模板 DNA、 DNA 连接酶、 寡核苷酸引物在相应的反应条件下, 首先加热至一定温度下 (94 95Ό) 使 DNA 变性, 双链打开, 然后降温退火 (65Ό左右), 引物与之互补的模板 DNA 结合并留下一缺口,如果与靶序列杂交的相邻的寡核苷酸引物与靶序列完全互补, DNA连接酶即可连接封闭这一缺口, 则 LCR反应的三步骤 (变性-退火-连接)就能 反复进行, 每次连接反应的产物又可在下一轮反应中作模板, 使更多的寡核苷酸 被连接与扩增。 若连接处的靶序列有点突变, 引物不能与靶序列精确结合, 缺口 附近核苷酸的空间结构发生变化, 连接反应不能进行, 也就不能形成连接产物。
LCR的引物是两对分别互补的引物, 引物长度为 20 ~ 26个, 以保证引物与靶 序列的特异性结合, LCR识别点突变的特异性高于 PCR, 其特异性首先取决于引 物与模板的特异性结合, 其次是耐热连接酶的特异性。 LCR连接反应温度接近寡 苷酸的解链温度 (Tm), 因而识别单核苷酸错配的特异性极高.
LCR 的扩增效率与 PCR相当, 用耐热连接酶做 LCR只用两个温度循环, 94°Cmin变性和 65°C复性并连接, 循环 30次左右.其产物的检测也较方便灵敏.目 前该方法主要用于点突变的研究与检测、 微生物病原体的检测及定向诱变等, 还 可用于单碱基遗传病多态性及单碱基遗传病的产物诊断, 微生物的种型鉴定, 癌 基因的点突变研究等。
根据连接酶链反应方法 ,针对 rtE218G突变设计两对分别与 HBV突变株 DNA 序列互补的相邻寡核苷酸链, 每对中的其中一条寡核苷酸链与另一条相邻, 且相 邻端的末尾碱基与 rtE218G突变位点的碱基互补。 以待检 HBV DNA为模板进行 连接酶链反应, 检测连接产物, 判断是否发生 rtE218G突变。
4、 核苷酸测序法: 釆用 PCR扩增目的 DNA片段, 待检测的 DNA片段, 直 接通过核苷酸序列测定, 来判断是否为突变株。 PCR产物也可先进行克隆, 然后 挑多个菌落进行测序分析。
5、 序列特异性引物法: 根据突变位点, 设计合成序列特异性引物。 采用 PCR 扩增目的 DNA片段,由于野生或者突变的序列只会和相应的引物互补结合得以扩 增, 故通过检测特异扩增产物的有无判断是否为突变株。 优选结合探针进行定量 PCR。在本发明的一个实施例中,采用特异性引物 F1:5,-GAG TGG GCC TCAGTC CGT TTC TC-3' , F2: 5 '-TTG GTA ATA GAG GTA AAA AGG TTT C-3 ' , 荧光标 记探针: FAM-5'-TAG TGC CAT TTG TTC AGT GGT TCG TAG-3'-TAMRA, 进行 定量 PCR检测, 只有突变株才能检测得到特异性扩增。
6、 聚合酶链反应 -单链构象多态性分析 ( Single Strand Conformation Polymorphism Analysis of Polymerase Chain Reaction Products, PCR-SSCP )是近年 来发展起来的一种基因分析方法。
PCR-SSCP分析的基本程序为: 首先 PCR扩增特定靶序列, 然后将扩增产物 变性为单链, 进行非变性聚丙烯酰胺凝胶电泳。 在不含变性剂的中性聚丙烯酰胺 凝胶中电泳时, DNA单链的迁移率除与 DNA链的长短有关外, 更主要的是取决 于 DNA单链所形成的构象。 在非变性条件下, DNA单链可自身折叠形成具有一 定空间结构的构象。 这种构象由 DNA单链碱基决定, 其稳定性靠分子内局部顺序 的相互作用 (主要为氢键)来维持。 相同长度的 DNA单链其顺序不同, 甚至单个 碱基不同, 所形成的构象不同, 电泳迁移率也不同。 PCR产物变性后, 单链产物 经中性聚丙烯酰胺凝胶电泳, 靶 DNA中含碱基置换,或数个碱基插入或缺失等改 变时, 因迁移率变化会出现泳动变位, 从而可将变异 DNA与正常 DNA区分开。 由此可见, PCR-SSCP分析技术是一种 DNA单链凝胶电泳技术, 它根据形成不同 构象的等长 DNA 单链在中性聚丙烯酰胺凝胶中的电泳迁移率变化来检测基因变 异。 该技术巳被广泛用于癌基因和抗癌基因变异的检测、 遗传病的致病基因分析 以及基因诊断、 基因制图等领域。
为了高灵敏特异性地显示 SSCP分析结果, 现已发展多种 PCR-SSCP技术, 各有其优势及适用领域。 例如, 可以在 PCR扩增中用同位素或荧光素等标记引物 或核苷, 也可以在电泳后用银染或溴化乙锭染色以显示结果。 这里将重点介绍最 常用的放射性同位素 PCR- SSCP法。 在进行 PCR扩增特定靶基因序列时, 利用 γ -32P-ATP标记引物或直接在 PCR反应体系中加入 a -32P-dCTP进行 PCR扩增, 使扩增产物带有同位素标记物, 然后将扩增产物变性为单链进行非变性聚丙烯酰 胺凝胶电泳, 放射自显影显示结果。 利用引物标记或碱基掺入法使 PCR扩增产物 带有同位素标记物, 均可使产物信号增强几个数量级。 二者相比较, 前者经济、 扩增特异性强, 多用于大样本的检测和筛选; 后者操作简便, 适于一般实验室开 展, 可用于小样本或大样本的检测和筛查。
本发明进一步提供检测 rtE218G突变位点和鉴定相应 HBV突变病毒株的检测 试剂, 其中包括各种引物和 /或探针。 还可以进一步将所述检测试剂和必要的其它 试剂组装成检测试剂盒以方便使用。 例如, 将上述引物与限制性内切酶等组成
PCR-RFLP检测试剂盒, 或者将位点特异引物与荧光探针组成荧光定量 PCR检 测试剂盒等等。 - 具体地说, 所述检测试剂可选自:
1 ) 引物对, a、 其特异性地扩增包括 rtE218G突变位点的核苷酸序列; 或 b、 其扩增产物包括 rtE218G突变位点并且该位点与两端或一端序列可以构成限制性 内切酶的识别位点;
• 2 )序列特异性引物对, 其中一条引物特异性地与包含 rtE218G突变位点的核 苷酸序列结合;
3 )特异性探针, 其特异性地与包合 rtE218G突变位点的核苷酸序列结合;
4 )用于连接酶链反应的寡核苷酸序列,根据连接酶链反应方法,针对 rtE218G 突变设计两对分别与 HBV突变株 DNA序列互补的相邻寡核苷酸链, 每对中的其 中一条寡核苷酸链与另一条相邻, 且相邻端的末尾碱基与 rtE218G突变位点的碱 基互补。
当该上述试剂盒包含 1 )中所述的引物对时, 其还包含所述限制性内切酶; 当 包含 2 ) 中所述的序列特异性引物时, 其还包括与目的序列特异结合的探针。
检测 HBV rtE218G突变的方法和鉴定相应 HBV突变病毒株的方法可以仅用 于实验室研究, 或仅通过上述方法检测或鉴定出适用于耐药监测和新药开发的 HBV rtE218G突变位点和相应的 HBV突变病毒株。 HBV rtE218G突变也可以用于 临床指导用药。本发明还提供临床指导用药的方法,包括检测 HBV rtE218G突变, 根据检测结果选择用药。 当然, 在检测 HBV rtE218G突变时可以优选使用上述的 试剂或试剂盒进行检测。 本发明中 rtE218G变异位点的发现, 能够结合巳知变异 位点解释临床 ADV耐药现象。 通过检测该变异位点, 可以用于临床指导用药, 以 及新药的开发和筛选。 附图说明
图 1显示各质粒经内切酶 和 III双酶切后, 产生 1.2倍 HBV全长 基因 (约 3.8kb )和 PUC18载体片段(约 2.8kb ); 图 2为突变质粒测序图, 以验证诱变部位的正确引入, 其中诱变核苷酸位置 由箭头指出, 下划线处为编码相应诱变氨基酸的密码子;
图 3为 Southern bloting结果, 显示不同浓度 ADV对野生株和 rtE218G突变 株 HBV复制中间体的抑制作用;
图 4为根据 Southern bloting 的结果进行灰度值分析而得到的剂量效应曲线, 显示 ADV对野生株和 rtE218G突变株不同的抑制作用, 突变株 IC50为野生株的 5.5倍。 具体实施方式
以下实施例进一步说明本发明的内容, 但不应理解为对本发明的限制。 在不 背离本发明精神和实质的情况下, 对本发明方法、 步骤或条件所作的修改或替换, 均属于本发明的范围。
若未特别指明, 实施例中所用的技术手段为本领域技术人员所熟知的常规技 术手段。 实施例 1
1. 血清:
ADV治疗无效的慢性乙型肝炎患者血清标本, 存于 -3 (TC备用。
2. 质粒和受体菌:
质粒 PUC-HBV 1.2WT含 1.2拷贝 HBV DNA (基因型 C, Genbank引入号为 AY518556 ),由北京大学人民医院肝病研究所保存。 A-T克隆所用 pGEM-T Easy 载 体试剂盒购自美国 Promega公司, DH5a感受态细胞购自鼎国生物技术公司。
3. 主要试剂:
蛋白酶 K、 Poly(A)、 dNTPs、 糖原购自德国 Boehringer Mannheim ( BM )公 司, X-gal、 IPTG购自美国 Promega公司, 琼脂糖、 二乙基焦碳酸酯(DEPC )购 自 Fluca公司, 胰蛋白胨、 酵母提取物购自 Oxid公司, 酚购自 Invitrogen公司, DMEM培养基、 胎牛血清购自 GIBCO公司, 磷酸硝基苯酚 pNPP购自 Sigma公 司, 其它生化试剂为国产分析纯试剂。
DNA凝胶回收纯化试剂盒(QIA quick Gel Extraction Kit )及质粒提取纯化试 剂盒( EndoFree TM Plasmid Mega Kit )为德国 Qiagen公司产品, 高效真核转染试 剂 VigoFect购自威格拉斯生物技术 (北京)有限公司, HBsAg和 HBeAg的测定 使用 ARCHITECT®微粒子化学发光检测试剂盒(Abbott公司, 美国) HBV DNA 荧光定量 PCR试剂盒购自深圳匹基生物工程有限公司。 地高辛探针标记试剂盒、 抗地高辛抗体和 CPD Star试剂盒购自德国 Roche公司。
4. 工具酶:
高保真 DNA聚合酶购自北京全式金生物技术有限公司, T4 DNA连接酶购自 美国 Promega公司, 各种限制性内切酶购自美国 ΝΈΒ公司。
5. 肝癌细胞株:
人肝癌细胞系 HepG2购自中国科学院细胞生物研究所, 冻存于液氮中, 复苏 后培养于 37°C、 5%C02 孵箱内, 用含 10%胎牛血清的高糖 DMEM培养基培养。
6. 阿德福韦酯:
阿德福韦酯(adefovir dipivoxil ), 冻干粉剂, 4°C保存, 用 PBS溶解后, -20°C 保存。
7. 主要仪器和耗材:
高速低温离心机 CF15R为 HITACHI公司产品,台式高速离心机 Micromax为 德国 IEC公司产品, PTC- 100 Peltier Thermal Cycler PCR仪为美国 MJ Research 公司产品, 凝胶自动成像系统 GEL Doc2000为 Bio-Rad公司产品, 恒温孵箱为美 国 Revco公司产品, 恒温气浴摇床为哈尔滨东明医疗仪器厂产品, 二氧化碳培养 箱 3111为 Forma Scientific公司产品,超净工作台为北京昌平长城空气净化工程公 司产品, 高压灭菌蒸锅 MLS-3000为 SANYO公司产品, 酶标仪 Reader 230s为 DRGAnon Teloiika公司产品, 荧光定量 PCR仪 LightCycler II为 Roche公司产品。
8. 引物设计和测序:
检测方法中应用的引物根据 GenBank中各 HBV基因型序列设计, 在相应位 置引入变异位点; 其余的引物根据 PUC-HBV1.2WT中 HBV序列设计。 所有引物 均由北京三博远志生物技术公司合成。 测序工作由北京诺赛基因组研究中心有限 公司完成, 测序试剂为 ABI BigDye3.1 , 测序仪器为 ABI 3730XL。
二、 实验步骤
1. ADV耐药的慢型乙型肝炎患者血清样本进行聚合酶区扩增, 其 PCR产物进 行克隆测序。
采用蛋白酶 K- 酚氯仿法提取血清样本中的病毒 DNA, 溶于 30 μ 1 ΤΕ中, - 80 °C保存备用。 '
每个 PCR反应体系 30μ1, 包含 10 x PCR buffer 3 μ 1, 10mmol/L dNTP 1 μ1, 上 游引物和下游引物各 50ng, 高保真 Taq酶 lu, 最后根据模板量, 加入 DEPC水, 使总反应体系达到 30μ1。
首先各取从患者血清中巳提取的 HBV DNA 3 μ ΐ为模板,以 BSE(上游: 5,-CTC GTG GTG GAC TTC TCT CA-3' )及 PO (下游: 5,-GGG TTG CGT CAG CAAACA CTT G-3' )为引物, 扩增条件为 94 Ό 300秒, 94 °C 30秒, 55 °C 30秒, 72 °C 45 秒, 30个循环。 取 3μ1第一次 PCR产物, 再以 Hinfed (上游: 5,-GAG TGG GCC TCA GTC CGT TTC TC-3 ' )和 SSG(下游: 5,- ACA TAT CCC ATG AAG TTAAG-3 ' ) 为引物进行二次 PCR扩增, 94Ό 300秒, 94 °C 30秒, 55°C 30秒, 72 °C 45秒, 35个循环。 得到的 244bp 大小的 PCR产物。 PCR产物无需经经过纯化, 直接将 PCR产物与 pGEM-T Esay Vector连接。 连接体系含:
2χ快速连接缓冲液 5.0μ1
pGEM-T Easy载体(50ng^l ) 0.5,μ1
T4 DNA连接酶( 3 Weiss unit/μΐ ) 0.5 μΐ
PCR产物 2 ~ μ1
d¾0补足至反应总体积为 ΙΟ.ΟμΙ
4°C连接过夜。 取 5μ1连接产物, 加入 ΙΟΟμΙ DH5a感受态细菌, 轻轻混匀冰上静 置 20分钟。 42。C循环水浴热休克 60秒, 置于冰上 2分钟。 加入 lml 37°C预温的 LB培养液, 37°C振荡 (250rpm )培养 1小时。
将合适体积的转化产物涂于含有 100mg/ml氨苄青霉素的 LB培养板 (含 lmol/1 IPTG 4μ1, 20mg/ml X-gal 40μ1 ) 上, 37。C倒置培养过夜。
挑取 24个白色菌落, 接种于 2ml含 100mg/ml氨苄青霉素的 LB培养液中, 37。C振荡 (250rpm ) 培养过夜。 转移培养过夜产物 1.5ml至离心管中, 5,000rpm 离心 30 秒, 弃上清, 细菌悬浮于 ΙΟΟμΙ 溶液 I ( 50mmol/L 葡萄糖, 50mmol/LTris-HCl(pH8.0), lOmmol/L EDTA )中, 室温静置 5分钟。 加入 200μ1 溶 液 II ( 0.2mol/L NaOH, 1%(W V)SDS ), 轻柔颠倒混匀 5-6次, 冰上静置 5分钟。 加入 150μ1 溶液 III ( 3mol/L KAc, 2mol/L HAc ), 轻轻震荡混匀, 冰上静置 5分 钟, 12,000ipm离心 5分钟。 转移上清至新离心管, 加入 900μ1 无水乙醇, 混匀, 室温静置溶液 5分钟, 12,000rpm离心 5分钟。 弃上清, 室温静置干燥沉淀, 加入
ΙΟΟμΙ 溶液 IV ( 2(^g/ml RNase TE (pH8.0) )悬浮沉淀, 即为质粒溶液。 Eco U 酶 切鉴定: ·
反应体系含:
ΙΟχ酶缓冲液 Ι .ΟμΙ
EcoR I ( lOunit/μΙ ) 0.2μ1
质粒 0.2μδ
d¾0补足至反应总体积为 ΙΟμΙ
37°C酶切 1小时。 1.0%琼脂糖凝胶电泳, EB染色, 紫外灯下观察结果。 根据插 入片段的长度判断是否有 HBV基因插入。
挑取阳性菌落, 增菌后提取质粒进行上述限制性酶切分析鉴定后测序。
2. 采用 PCR介导的定点诱变技术构建诱变质粒 ' 质粒 PUC-HBV 1.2WT为含 1.2拷贝 HBV DNA (基因型 C, Genbanl 引入号 为 AY518556 ), 第一轮 PCR先以 PUC-HBV1.2WT 2ng为模板, 分别用两对引物 P1A- 2(上游: 5,- GAACATCGCATCAGGACTCCTAGGACCCCTG-3' )和 E218-3(下
GCATAAAGGGACCCAAG-3') , E218-P1 (上游: 5'-CAACATCTTGGGTCCCTTT ATGC-3')和 P2A (下游: 5,-GGCATTAAAGCAGGATATCCAC-3, )进行 PCR扩增 , 扩增体系同上所述, 扩增条件为 94°C 300秒, 94°C 45秒, 55°C 45秒, 72Ό 60 秒, 35个循环后, 72Ό 延伸 7分钟。 分别获得 680bp大小的片段 A和 287bp大 小的片段^ 片段 A和 B分别通过凝胶回收纯化试剂盒(德国 Qiagen公司)纯化 回收。 等比混合纯化后片段 A和 B并且经过 1 : 100倍稀释后, 取 3μ1作为第二轮 融合 PCR反应模板, 应用引物 P1A-2和 Ρ2Α扩增, 反应体系同上, 扩增条件为 为 94°C 300秒, 94Ό 60秒, 55 °C 60秒, 72°C 60秒, 35个循环后, 72°C 延伸 7分钟, 获得 899bp的片段 C, 经过 A-T克隆(同上所述), 0R I限制性酶切和 序列测定鉴定诱变成功的阳性克隆。 以限制性内切酶 o?R V和 ^vr ll双酶切此阳 性克隆和质粒 pUC-HBVL2WT, 定向连接和克隆后, 获得 rtE218G 诱变质粒 PUC-HBV1.2-E218G ( SEQ ID NO.20 ). 含有该诱变质粒的菌种已于 2009年 05月 26曰在中国微生物菌种保藏管理委员会普通微生物中心 (地址: 北京巿朝阳区大 屯路甲 3号, 中国科学院微生物研究所, 邮编 100101 )保藏, 分类命名为大肠埃 希氏菌 ( Escherichia coH ~) PUC-HBV1.2-E218G, 保藏号为 CGMCC No.3079。
3. 药物敏感试验
人肝癌细胞株 HepG2复苏后在 37°C、 5% C02孵箱条件下, 含有 10%胎牛血 清的 DMEM培养基中呈单层贴壁细胞生长, 每隔 3〜5天以 1 : 3传代 1次。 转染 前 24小时,接种适量细胞(6孔板中每个孔约 2x 105 )。至转染时细胞密度以 40〜60% 为宜 (80~90%亦可)。 转染前 1 小时, 更换新鲜的完全培养液 (每孔 2ml ), 置 37V , 5% CO2 培养。 以每孔为例, 取 2 g DNA, 加入注射用生理盐水中至总体 积为 100 μΐ, 轻轻混匀, 室温放置。 取 VigoFect 2μ1, 加入注射用生理盐水中至 总体积为 100 μ1, 轻轻混匀, 室温放置 5分钟。 将稀释的. VigoFect逐滴加入稀释 的 DNA溶液中, 轻轻混匀, 所得的转染工作液在室温放置 15分钟。 将转染工作 液轻轻混匀, 逐滴加入 2 ml培养液中, 轻轻混匀培养液, 置 37 °C , 5% C02 培养。 转然后第 2天, 更换培养基, 并分别加入终浓度为 0、 0.01、 0.1、 1、 5、 10和 20μΜ 的 ADV, 以后隔天更换培养基同时加抗 HBV药 /ADV, 转染后第 8天收获细胞。
5. 细胞培养上清中 HBV DNA定量检测
细胞培养上清经 lOO g/ml DNase I 37 °C处理 1小时以消化残余的转染质粒。 病毒 DNA检测在 Light Cycler II全自动荧光定量 PCR仪(Roche公司, 美国)上 进行, 使用 HBVDNA定量 PCR检测试剂盒, 样品处理和扩增按照产品说明书进 行。
HBsAg 和 HBeAg 的测定使用 ARCHITECT®微粒子化学发光检测试剂盒 ( Abbott公司, 美国)进行, 操作步骤计算方法按照说明书进行, HBsAg表示为 IU/ml , HBeAg表示为 S/CO值。
6. Southern blotting检测 HB V胞内复制中间体。
6.1 全基因组 HBV DNA探针制备
PC 法地高辛标记全基因组 HBV DNA探针的制备按照试剂生产者提供的说 明书进行。 反应引物: 上游 Dl, 5 '-CCGGAAAGCTTGAGCTCTTCTTTTTCAC CTCTGCCTAATCA-3' ; 下游 D2, 5 '-CCGGAAAGCTTGAGCTCTTCAAAAAG TTGCATGGTGCTGG-3,。 反应条件为: 94 °C预变性 2分钟, 94 °C 30秒, 55 °C 30 秒, 72°C 2分钟, 共 35个循环, 第 11个循环开始每个循环延伸时间增加 20秒, 最后 72°C延伸 7分钟。 取 PCR产物 Ιμΐ, 加入 Ιμΐ 6 x上样缓冲液, 4μ1 Η20, 经 过 1.0%琼脂糖凝胶电泳, 0.5 g/ml EB染色, 紫外灯下观察结果。 注意预计产物 长度由于掺入地高辛标记 dUTP片段电泳速度较慢, 电泳结果显示的片段大小略 大于 3.2kb。 用 Qiagen凝胶回收纯化试剂盒回收纯化 PCR产物并和标准含量探针 比较定量。
6.2 细胞质中 HBV复制中间体的提取
收获的细胞, 以 PBS洗两遍, 然后每孔中加入 300μ1细胞裂解液(50mmol L Tris-HCl, pH7.4, lmmol/1 EDTA, 1% NP-40 ), 充分溶解破裂细胞。 溶解的细胞转 移至 L5ml EP管, 震荡后置于冰上 15分钟, 再次震荡后 14,000rpm, 离心 1分钟 去除细胞核。 收集上清至新离心管中,加入终浓度 10mol/l MgCl2、 lOO g/ml DNase I 37°C 1小时消化游离 HBV DNA。加入终浓度为 25mmol/L的 EDTA终止 DNase I消化反应。加入终浓度为 0.5mg/ml蛋白酶 K及 1% SDS, 60 °C 裂解 1小时 酚: 氯仿:异戊醇(25: 24: 1 , V/V )抽提两遍。 取上清加入 2.5体积无水乙醇, 0.25 体积 10mol/L 醋酸铵, Ιμΐ (20mg/ml)糖原, -20°C沉淀过夜。 14000rpm, 4°C离心 15分钟, 吸弃上清。 用 4°C预冷 70%乙醇洗 2遍, 14000rpm 4°C离心 5分钟。 获 得的 HBV DNA溶于 ΙΟμΙ含 2(^g/ml RNase A的 TE中。
6.3细胞质中 HBV复制中间体的 Southern blot杂交检测
将提取的细胞质中的 HBV复制中间体进行 1.0%琼脂糖电泳。 电泳结束后, 于 5倍凝胶体积变性液中 (0.5mol/LNaOH, 1.5mol/L NaCl )室温下于脱色摇床上 轻摇动 45min变性, 将胶用蒸馏水简单漂洗后, 换到约 5 x体积中和液中( lmol/L Tris-HCl, pH7.4, 1.5mol L NaCl ) 中和两遍, 每次中和 30min。 准备与胶大小相 同的一张尼龙膜、 6 张 3MM 滤纸, 将尼龙膜和 3MM 滤纸浸入到转移缓冲液 0.5XTBE中 5min, 准备电转移装置, 根据 DNA泳动方向, 用平镊从负极至正极 依次铺海棉、 3层 3MM滤纸、 琼脂糖凝胶、 尼龙膜、 3层 3MM滤纸、 海棉, 对 齐后室温下 40伏特恒压电泳转膜(<400mA ) 2- 4小时。
停止电泳, 以铅笔标记凝胶加样孔的位置, 在 5XSSC中洗一下以去除琼脂碎 片。 取出尼龙膜, 吸干液体后平放于纸巾上, 室温自然干燥 30min。 将尼龙膜携 带 DNA的一面暴露于紫外线, lOOmJ/cm2进行紫外交联固定。 将固定后的尼龙膜 膜漂浮于 5xSSC液面, 由下至上完全浸润 2分钟。 将浸润的膜放入杂交瓶中, 按 每平方厘米滤膜加入 ΙΟΟμΚ lOml/lOOcm2 )预热至 42°C的预杂交液 DIG Easy Hyb。 在 42°C杂交箱中预杂交 30min。
倒尽预杂交液, 将 42 °C预热好的杂交液 Dig High Hyb ( 3.5ml/100cm2 )加入 杂交瓶中, 加入经过 100°C5分钟变性的终浓度 25ng/ml的地高辛标记 HBV全基 因组探针。 杂交反应在 42°C杂交箱中杂交过夜。
取出杂交膜置于 15cm培养皿中, 加入约 200ml 2xSSC和 0.1% SDS溶液, 室 温下于脱色摇床上轻摇 5minx2。
倒尽洗液, 加入预热至 65°C的 0.5xSSC和 0.1% SDS溶液 200ml, 于预热至 65°C的杂交箱操中 65 °C轻摇 20minx2。 以 2xSSC简单漂洗一次。
取出杂交膜,在 I X封闭液中(含 1%封闭剂的马来酸 buffer: O.lmol/L 马来酸, 0.15mol L NaCl, pH7.5 ) 室温封闭 30min。
去除封闭液, 加入以 lx封闭液 1 : 5000 稀释的抗-地高辛抗体, 室温孵育 30min。 用 200ml马来酸洗液(合 0.3% Tween-20的 l x马来酸缓冲液)洗膜, 室温 15min洗膜 2遍。 在检测缓冲液( 0.1M Tris-HCl, O.lM NaCl, pH9.5 )中漂洗 5min。 以检测缓冲液 1: 200稀释 CSPD ( 25 mmol L, 11.6 mg/ml ), 用纸巾吸干尼龙膜 上的液体, 放于保鲜膜上, 将稀释好的 CSPD以 lml/100cm2体积加至尼龙膜上并 涂匀。 用保鲜膜夹好尼龙膜, 室温作用 5min后, 用滤纸吸干多余 CSPD, 37°C继 续孵育 10min。 在暗室中将 X 光片和用保鲜膜裹好的尼龙膜压于暗盒中, 曝光 15-20min。 冲洗 X光片, 用图像分析软件 Quantity One对转染细胞中 HBV复制中 间体进行相对灰度值的测定。
7. 培养上清 SEAP的测定
共转染内参质粒 PSEAP2, 测定细胞培养上清中 SEAP的活性, 可检测转染效 率, 除外实验偏差如转染质粒和转染细胞数量的差别而导致的病毒表达抗原及病 毒复制转录的区别,另外还可鉴定是否由于 ADV的细胞毒性作用所致的转染细胞 数量减少导致的病毒测定指标下降。 针对同样处理的共转染 SEAP质粒的 HepG2 细胞, 检测细胞培养上清中的 SEAP, 发现 SEAP的分泌值相近, 数值之间相比较 差值 <5 % -10%, 提示实验偏差可以忽略不计, 各组间的实验结果可以直接进行比 较。 具体检测过程如下: ' ΙΟΟμΙ细胞培养上清经 65°C , 30分钟热灭活内源性碱性磷酸酶, 14,000 X g, 2 分钟离心去除细胞碎片。(上清液可于 -20°C保存)。取 50μ1已处理的细胞培养上清 转移至 96孔板,平衡至 37°C,设置复孔,然后加入 45μ1已平衡至 37°C的 2 x SEAP 缓冲液 (20mmol/l高精氨酸, lmmol/L MgCl2, 21%乙醇胺, pH 9.8 ) 和 5μ1底物 溶液 (120 mmol/L磷酸硝基苯酚, 以 2X SEAP试剂缓冲液配制,)。 检测板置 37 °C显色 15分钟后, 测 A405吸光度值。
三、 实验结果
1. 发生临床 ADV耐药后患者血清变异位点检测结果
23例患者中, 有 5例除检出 rtE218G夕卜, 还检出 rtA181V/T和 /或 rtN236T 变异位点, 其余 18例只检出 rtE218G变异位点。
2. rtE218G诱变 HBV表达质粒的构建和鉴定
利用 PCR定点诱变技术, 以野生型 HBV复制质粒 PUC-HBV1.2WT为模板, 构建得到 rtE218G变异株表达质粒, 命名为 PUC-HBV1.2-E218G。 对诱变质粒进 行 coR I和 III双酶切鉴定, 结果见图 1 ; 对变异位点进行测序验证, 测序结 果见图 2, 与野生型相比, 聚合酶区发生了 rtE218G突变, 密码子由 GAG变成了 GGG。
3. 野生型和阿德福韦耐药变异 HBV表达质粒转染后在 HepG2细胞中的抗原表 达、 上清中病毒颗粒分泌水平
野生型和上述诱变质粒瞬时转染 HepG2细胞 96小时后 ,收集细胞及培养上清, 以质粒 pSEAP2表达的外源性碱性磷酸酶水平进行转染效率校正, 检测到野生型 和诱变型 HBV表达质粒转染组上清中存在较高水平的 HBeAg、HBsAg,病毒 DNA 拷贝数达到 (4,52 ± 0.83) 105( copies/ml)和 (4.25 ± 0.14) 105(copies/ml), 提示诱变 质粒转染 HepG2细胞后能够建立 HBV的复制状态并表达病毒抗原和分泌病毒颗 粒。
4. 野生型、 rtE218G变异株病毒复制能力的比较
野生型和诱变质粒瞬时转染 HepG2细胞 96小时后, 测定上清中 HBV DNA和 细胞浆内 HBV复制中间体水平。 结果表明变异株的病毒复制能力低于野生株, 为 野生株的 87%。
5. 野生型、 rtE218G变异株对阿德福韦的敏感性 野生型和上述诱变质粒瞬时转染 HepG2细胞后分别加入终浓度为 0、0.01、0.1、 1、 5、 10和 20μ 的阿德福韦进行处理 7天后, 检测细胞浆内 HBV复制中间体, Southern blotting结果如图 3所示, 不同浓度阿德福韦对野生株和变异株复制中间 体的抑制作用。进行相对灰度值分析后,根据不同浓度药物对复制中间体水平的影 响进行定量分析,应用 SPSS 10.0统计软件作出各剂量效应曲线,结果如图 4所示, 并计算出阿德福韦对野生株和变异株的半数有效抑制浓度 (IC50 值), 分别为 1.7μΜ和 9.3μΜ。 rtE218G变异株的 IC50是野生株的 5.5倍。 实施例 2 突变位点的检测
本例中提供三种不同的检测方法, 对 rtE218G突变位点进行检测。
1、 聚合酶链式反应一限制性片段长度多态性 (PCR— RFLP )分析法 根据 GenBank中 HBV各基因型参考株序列, 设计诱变引物 B2 (下游 5'-TTG GTA ATA GAG GTA AAA AGG TAC-3 ' ), 该引物与 rtE218G的变异位点共同构成 可被 内切酶识别的酶切位点。 另设计引物上游引物 B 1 (上游 5,-GAG TGG GCC TCA GTC CGT TTC TC-3 ' ), 然后采用 PCR扩增目的 DNA片段, 扩增条件: 94 V 60秒, 94°C 30秒, 60°C 45秒, 35个循环, 扩增片段长度为 160bp。 采用 α« Ι限制性内切酶分析检测。 酶切体系: l O x酶缓冲液 Ι μ ΐ, 酶 5U, PCR产物 2-4 μ ΐ, 加 DEPC水至总体积 10 μ 1。 酶切条件: 37V , 2 ~ 4小时。 结果突变株被 切成 140bp和 20bp两个片段, 野生株不被切开, 保持 160bp的片段。
2、 核苷酸序列测定
釆用套式 PCR 扩增目的 DNA 片段。 外侧引物为, 上游 SA: 5 '-TCG TGT TACAGGCGGGGT TT-3' , 下游 P0: 5,-GGG TTG CGT CAG CAAACA CTT G-3'; 内侧引物为, 上游 BSE: 5 '-CTC GTG GTG GAC TTC TCT CA-3 % 下游 1162: 5'-TTG CCG GGC AAC GGG GTAAAG-3,。扩增条件为 94 °C 300秒, 94 Ό 30秒, 55 °C 30秒, 72 °C 45秒, 35个循环。 取 3μ1 1 : 100稀释的第一次 PCR产物, 作 为第二次的模板。 得到 910bp大小的 PCR产物, 可直接通过核苷酸序列测定; 也 可先进行 A-T克隆, 然后挑多个菌落进行测序分析。 最终根据测序结果, 直接判 断是否为突变株。
3、 序列特异性引物法: 根据突变位点, 设计合成序列特异性引物 F1 :5,-GAG TGG GCC TCA GTC CGT TTC TC-3,, F2: 5' -TTG GTA ATA GAG GTA AAA AGG TTT C-3' , 荧光标记探针: FAM-5,-TAG TGC CAT TTG TTC AGT GGT TCG TAG-TAMRA-3'。 采用荧光定量 PCR扩增目的 DNA片段, 扩增条件为 42 °C 120 秒, 94°C 120秒, 然后 94°C 10秒, 65 °C 20秒, 40个循环。 结果表明只有突变 株才能得到特异性扩增, 这是由于只有已发生 rtE218G突变的序列能够和的引物 互补结合。
工业实用性
本发明公开了 HBV rtE218G突变位点, 发现其与阿德福韦耐药有关, 本发明 进一步提供了检测 HE218G突变位点的方法和相关的试剂。 通过检测该变异位点, 来指导临床用药, 以及新药的筛选。
DO NOT DELETE THIS PAGE 中国微生物菌种保藏管理委员会
普通 生物中心
China General Microbiological Culture Collection Center(CGMCC) 地址: 北京市朝阳区大屯路, 中国科学院微生物研究所, 邮政编码: 100101, http://www.cgmcc.net 电话: 010-64807355 传真: 010-64807288 电子邮件: cgmcc@sun.im.ac.cn 受理通知书 (收据)
存活性报告书 用于专利程序的生物材料保存 发出日期 2009年 05 月 26 日
(请求保藏人或代理人的姓名、 地址)
- 魏来
Figure imgf000019_0001
该微生物 (株) 已于 2Q<39 年 05 月 26日由本保藏中心收到, 并登记入册。
根据你 (们) 的请求, 由该日起保存三十年, 在期满前收到提供生物材料样品的请求后再 延续保存五年。
该生物材料(株) 的存活性经本保藏中心于 2QQ9 年 Q5 月 26 日检测, 结果是
( 1 )存活 (2) 失活 I
Figure imgf000019_0002

Claims

权 利 要 求 书
1、 一种 HBV突变株, 其特征在于, 该病毒株的聚合酶基因 218位的氨基酸 密码子由 GAG突变为 GGG, 即发生了 HE218G突变。
2、 一种鉴定权利要求 1所述 HBV突变株的方法, 其步骤包括:
1 )采用 PCR扩增含有 rtE218G突变位点的目的 DNA片段;
2 )扩增产物用限制性内切酶进行酶切, 所述限制性内切酶的识别序列包含所 述 rtE218G突变位点;
3 ) 步骤 2 ) 中的酶切产物进行琼脂糖电泳, 根据不同的切割条带来判断是否 发生了 rtE218G突变。
3、 如杈利要求 2所述的方法, 其特征在于步骤 1 ) 中扩增目的 DNA片段的 引物对为 B1和 B2, 其核苷酸序列分别如 SEQ ID N0.2和 SEQ ID N0.1所示。
4、 如权利要求 2所述的方法, 其特征在于步骤 2 ) 中所述的限制性内切酶为 ' Ban I内切酶。
5、 一种鉴定权利要求 1所述 HBV突变株的方法, 其步骤包括:
1 )采用 PCR扩增包含 rtE218G突变位点的 DNA片段;
2 ) 对步骤 1 ) 中扩增的 DNA片段进行核苷酸序列测定;
3 ) 根据测序结果判断是否发生了 rtE218G突变。
6、如权利要求 5所述的方法,其特征在于步骤 1 )中采用的 PCR为套式 PCR。
7、 如权利要求 6所述的方法, 其特征在于套式 PCR所使用的外侧引物对为 SA和 P0, 其核苷酸序列分别如 SEQ ID N0.18 和 SEQ ID N0.7 所示。
8、 如权利要求 6所述的方法, 其特征在于套式 PCR所使用的内侧引物对为 BSE和 1164, 其核苷酸序列分别如 SEQ ID NO.6 和 SEQ ID N0.19 所示。
9、 一种鉴定杈利要求 1所述 HBV突变株的方法, 其步骤包括:
1 )根据突变位点, 设计合成序列特异性引物;
2 ) PCR扩增目的 DNA片段, 通过检测特异扩增产物的有无, 来判断是否 发生了 rtE218G突变。
10、如权利要求 9所述的方法,其特征在于步骤 2冲使用的 PCR为定量 PCR。
11、 如权利要求 9所述的方法, 其特征在于 PCR扩增所使用的序列特异性引 物为 Fl , 其核苷酸序列如 SEQ ID N0.3 所示。
12、 如杈利要求 11所述的方法, 其特征在于与 F1配对使用的另一条引物为 F2, 其核苷酸序列如 SEQ ID NO.4 所示。
13、 如杈利要求 10所述的方法, 其特征在于荧光定量 PCR使用核苷酸序列 如 SEQ ID N0.5所示的荧光标记探针。
14、一种鉴定杈利要求 1所述 HBV突变株的方法,其特征在于用针对 rtE218G 突变位点的探针与待检 HBV DNA片段, 通过检测杂交结果, 来判断是否发生了 rtE218G突变。
15、 如杈利要求 14所述的方法, 其特征在于, 所述探针固定在杂交膜上, 通 过 PCR法获得带有标记的包含待检位点的 HBV DNA片段, 将所述 DNA片段与 探针杂交, 洗掉未杂交的 DNA片段, 检测杂交结果, 来判断是否发生了 rtE218G 突变。
16、 如权利要求 15所述的方法, 其特征在于所述标记为生物素标记, 杂交后 加入标记有碱性磷酸酶的链霉亲和素, 使其与杂交产物上标记的生物素结合, 最 后加入 BCIP/NBT显色, 进而根据杂交结果, 来判断是否发生了 rtE218G突变。
17、 一种鉴定权利要求 1所述 HBV突变株的方法, 其特征在于根据连接酶链 反应方法, 针对 rtE218G突变设计两条与 HBV突变株 DNA互补的两个相邻寡核 苷酸链, 其中一条寡核苷酸链与另一条相邻的一端与 rtE218G突变位点的碱基互 补, 以待检 HBV DNA为模板进行连接酶链反应, 检测连接产物, 判断是否发生 rtE218G突变。
18、 一种检测试剂, 其特征在于, 该试剂含有检测 HBV聚合酶基因 rtE218G 突变位点的引物和 /或探针。
19、 如权利要求 18所述的检测试剂, 其选自:
1 ) 引物对, a、 其特异性地扩增包括 rtE218G突变位点的核苷酸序列; 或 b、 其扩增产物包括 rtE218G突变突变位点并且该位点与两端或一端序列可以构成限 制性内切酶的识别位点;
2 )序列特异性引物对, 其中一条引物特异性与包含 rtE218G突变的核苷酸序 列结合;
3 )特异性探针, 其特异性与包含! iE218G突变的核苷酸序列结合 4 )用于连接酶链反应的寡核苷酸序列, 针对 rtE218G 突变设计两对分别与 HBV突变株 DNA序列互补的相邻寡核苷酸链, 每对中的其中一条寡核苷酸链与 另一条相邻, 且相邻端的末尾碱基与 rtE218G突变位点的碱基互补。
20、 如杈利要求 19所述的检测试剂, 其中 1 ) 的引物对 b为 B1和 B2, 其核 苷酸序列分别如 SEQ ID NO.1和 SEQ ID N0.2所示。
21、 如权利要求 19所述的检测试剂, 其中 2 ) 的序列特异性引物对为 F1和 F2,其核苷酸序列分别如 SEQ ID N0.3和 SEQ ID NO.4所示。
22、 如权利要求 19所述的检测试剂, 其中 3 ) 的特异性探针的核苷酸序列如 SEQ ID N0.5所示。
23、 如杈利要求 19所述的检测试剂, 其中包含 1 ) 引物对 a的检测试剂, 还 包括引物对 a的内侧引物或外侧引物, 组成套式 PCR的内侧引物和外侧引物。
24、如杈利要求 19或 23所述的检测试剂,其特征在于所述引物对 a为 SA和 P0 , 其核苷酸序列分别如 SEQ ID NO.18 和 SEQ ID N0.7 所示。
25、 如权利要求 24所述的检测试剂 , 其特征在于其还包括内侧引物对为 BSE 和 1164, 其核苷酸序列分别如 SEQ ID NO.6 和 SEQ ID NO.19所示。
26、 含有权利要求 18 - 25任一项所述试剂的检测试剂盒。
27、 如杈利要求 26所述的试剂盒, 其特征在于, 当该试剂盒包含权利要求 15 中 1 )所述的引物对 b时, 其还包含所述限制性内切酶; 当该试剂盒包含权利要求 15中 2 )所述的序列特异性引物对时, 其还包括与目的序列特异结合的荧光探针。
28、 HBV rtE218G突变在指导临床用药中的应用。
29、核苷酸序列如 SEQ ID NO. l和 SEQ ID N0.2所示的引物对 B1和 B2在制 备通过检测 HBV rtE218G突变而指导临床用药的试剂盒中的用途。
30、 核苷酸序列如 SEQ ID N0.18和 SEQ ID NO.7所示的引物对 SA和 P0在 制备通过检测 HBV rtE218G突变而指导临床用药的试剂盒中的用途。
31、核苷酸序列如 SEQ ID N0.6和 SEQ ID N0.19所示的引物对 BSE和 1164 在制备通过检测 HBV rtE218G突变而指导临床用药的试剂盒中的用途。
32、核苷酸序列如 SEQ ID N0.3和 SEQ ID N0.4所示的引物对 F1和 F2在制 备通过检测 HBV rtE218G突变而指导临床用药的试剂盒中的用途。
33、 核苷酸序列如 SEQ ID N0.5、所示的荧光探针在制备通过检测 HBV rtE218G突变而指导临床用药的试剂盒中的用途。
34、 一种药物筛选方法, 其特征在于, 以权利要求 1所述突变株为对象, 在 体外或体内筛选对所述突变株复制具有抑制作用的药物。
35、含有杈利要求 1所述 HBV突变株或包含有 rtE218G的 HBV DNA的载体。
36、 含有权利要求 35所述载体的宿主细胞。
37、 如杈利要求 36所述的宿主细胞, 其为大肠埃希氏菌 (^cAer /^ co/ PUC-HBV1.2-E218G, 保藏号为 CGMCC No.3079。
PCT/CN2009/001165 2009-05-04 2009-10-20 乙型肝炎病毒耐阿德福韦变异病毒株及其应用 Ceased WO2010127474A1 (zh)

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