小分子乙型肝炎病毒基因组缺失突变体结构分析

目的 了解小分子HBV基因组缺失突变体的基因结构及特点.方法 采用一步法PCR从慢性乙型肝炎患者血清中扩增全基因组HBV DNA,回收并克隆＜1 kh的小分子HBV DNA,测序并以BioEdit及VectorNTI 6.0软件分析基因结构特点.结果 获得基因长度介于174～986 bp之间的64种、共124个小分子HBV缺失突变体DNA,按基因结构特点分为3类,即3种GT-AG剪接变异体、29种"常规"缺失突变体及32种基因组内部含polyA的缺失突变体.所有小分子基因组缺失突变体在HBV各编码区及基因调控区均存在不同程度缺失,其中66%(42/64种)保留与HBV复制(包装)相关的所有顺式调控序列,48%(31/64种)保留X编码区.结论 乙型肝炎患者血清中普遍存在小分子HBV基因组缺失突变体,深入了解这些变异体的结构和功能,有助于进一步探索HBV的致病机制.     

23株HBeAg阳性慢性乙型肝炎患者病毒的全基因组分析

目的研究HBeAg阳性慢性乙型肝炎患者HBV变异特点。方法PCR扩增并克隆HBeAg阳性慢性乙型肝炎患者血清中HBV全基因组DNA,测序并进行基因结构分析。结果获得23株HBV全基因组DNA,它们均属于c或B基因型。与中国HBVB、C基因型参照序列相比,HBeAg阳性慢性乙型肝炎患者来源的HBV在表面抗原、P蛋白、X蛋白的反式激活区及增强子II／核心启动子区发生了一些有意义的共有变异。结论HBV变异可能与HBeAg阳性慢性乙型肝炎的发生、发展有关。     

慢性乙型肝炎前C区G1896A基因变异对HBV复制及疾病严重程度的影响

目的研究乙型肝炎病毒(HBV)前C区G1896A变异对乙型肝炎病毒复制及疾病严重程度的影响。方法选取43例慢性乙型肝炎及49例乙型肝炎肝硬化患者为研究对象。采用PCR技术检测HBV前C区G1896A位点变异及乙型肝炎基因分型。同时检测HBeAg、HBV DNA定量、肝功能血清生化指标。结果(1)发生HBV前C区G1896A变异患者的年龄大于野生株感染者(P0.01),发生肝硬化的可能性更大(P0.01)。(2)随着变异株感染率的增加,HBeAg阴性率较野生株组增加(P0.01),基因C型较野生株组增加(P0.05),HBV DNA水平降低差异意义(P0.05)。结论 HBV前C区G1896A变异与HBeAg的状态,HBV DNA的复制及疾病严重程度相关。     

HBsAg/HBsAb双阳性慢性乙型肝炎患者HBV S基因免疫逃逸相关变异分析

目的分析HBsAg/HBsAb双阳性慢性乙型肝炎患者HBV S基因主要亲水区免疫逃逸相关位点变异特点。方法收集89例HBsAg/HBsAb双阳性和148例HBsAg单阳性的慢性乙型肝炎患者血清及临床资料,提取患者血清HBV DNA,扩增患者HBV S基因并进行测序,应用DNASTAR Lasergene Meg Align软件对主要亲水区已有文献报道的46个免疫逃逸相关位点及新增N-糖基化变异进行比对分析。结果 2组患者在年龄、ALT、TBIL、HBV DNA载量和HBe Ag阳性率方面差异均无统计学意义(P均0.05)。HBsAg/HBsAb双阳性患者HBV S基因主要亲水区变异的总检出率为31.46%,明显高于HBsAg单阳性患者的18.92%(P0.05),其中s L110I/S、s T113N/S、s T131I/N/P和s S143L/M/T的变异检出率明显高于单阳性组;双阳性患者多位点联合变异检出率亦明显高于单阳性患者(20.22%vs.6.08%,P0.05)。双阳性患者新增N-糖基化变异检出率高于单阳性患者(7.87%vs.2.03%),差异具有统计学意义(P0.05)。结论 HBsAg/HBsAb双阳性患者比HBsAg单阳性患者的HBV S基因免疫逃逸相关变异种类更多,单位点和多位点联合变异检出率更高,并且新增N-糖基化变异检出率也更高,这些变异可能是引起慢性乙型肝炎患者HBsAg/HBsAb双阳性共存的驱动因素之一。     

慢性乙型肝炎拉米夫定耐药患者HBV基因型及ALT变化的观察

观察慢性乙型肝炎患者用拉米夫定治疗后HBVP基因变异与不同HBV基因型感染及HBV DNA复升水平和转氨酶变化.收集51例慢性乙型肝炎患者用拉米夫定治疗52-78周后发生YMDD变异的血清标本,对照组128例未用拉米夫定治疗的慢性乙型肝炎患者血清标本,应用聚合酶链反应方法,测定HBV DNA基因型;用限制性片段长度多态性分析方法(PCR RELP)测定HBV DNA YMDD变异;同时进行HBV DNA定量分析.结果显示51例拉米夫定治疗后HBV DNA基因变异患者以B型和C型为主,分别为10例(19.6%)和39例(76.47%),B C混和型2例(3.92%),未见其它基因型.拉米夫定治疗引起HBVDNAYMDD变异可以发生在不同HBV基因型感染的慢性乙型肝炎患者中,与对照组比较二者没有显著性差异.     

基因芯片技术检测在乙型肝炎病毒基因突变分析中的应用

目的:探讨DNA芯片在乙型肝炎病毒基因突变分析中的应用及临床意义。方法:用基因多态性检测芯片检测HBV DNA阳性慢性乙型肝炎(CHB)患者血清前C区1896/1814位点、基本核心启动子区(BCP区)1762/1764位点及P区528/552位点突变情况,并与血清转氨酶、血清HBV DNA复制程度、血清e系统进行对比分析。结果:未接受抗病毒药物拉米夫定治疗的12例HBsAg( )、HBeAg( )、HBeAb(-)的患者血清中未检测到病毒变异,其他患者中未检测到P区基因变异;30例接受拉米夫定治疗48-96周后的HBV DNA阳性患者中,有19例患者检测到YMDD变异,并出现血清转氨酶升高,HBV DNA复制再度活跃。结论:前C区、BCP区突变较多的出现在HBeAb( )的患者中并与HBeAg的阴性表型相关,BCP区突变与HBeAg/HBeAb血清学转换密切相关,而P区528/552位点突变更多的出现在接受拉米夫定治疗后的患者中,与拉米夫定耐药相关且加重肝损害;基因芯片技术检测乙型肝炎病毒多位点变异对临床判断病情具有一定的参考意义。     

阿德福韦酯联合拉米夫定对拉米夫定耐药的慢性乙型肝炎疗效观察

目的 比较阿德福韦酯联合拉米夫定治疗拉米夫定不同耐药位点变异的慢性乙型肝炎患者的疗效.方法 40例对拉米夫定耐药的慢性乙型肝炎门诊,住院患者根据耐药位点分为两组:联合用药A组和联合用药B组.A组患者为180位点变异组,B组患者为204位点变异.所有患者均治疗1年.治疗前和治疗后4局、12周、24周、48周分别检测血清HBV DNA和ALT.结果 两组患者治疗后平均ALT水平均显著降低,HBV DNA转阴率和ALT复常率显著增加,B组明显优于A组.结论 对于拉米夫定204位点变异的慢性乙型肝炎患者,阿德福韦酯联合拉米夫定疗效较180位点变异好.     

HBV基因型与干扰素抗病毒疗效的关系

目的:探讨HBV不同基因型对α-干扰素抗病毒疗效的影响.方法:选取应用α-干扰素进行抗病毒治疗的慢性乙型肝炎患者作为研究对象,观察其抗病毒疗效.患者的HBV基因型采用PCR微板核酸杂交-ELISA方法检测;血清HBV DNA复制水平采用荧光定量PCR检测;HBV前C区和BCP(基础核心启动子)区基因位点变异采用HBV基因多态性芯片进行检测.结果:94例慢性乙型肝炎患者的HBV基因型以C型、B型为主,未发现A、E、F基因型.HBV DNA高复制水平明显与C基因型及混合基因型有关.B基因型对α-干扰素抗病毒治疗的应答明显优于C、D型,而混合基因型对α-干扰素的应答最不敏感.仅B基因型对α-干扰素治疗产生完全应答.部分应答及无应答时HBeAg的转阴与HBV前C区nt 1 896位点变异、以及BCP区nt 1 762、nt 1 764双位点变异有关.C基因型HBV前C区及BCP区基因变异发生率明显高于B型.结论:HBV基因型与HBV DNA复制水平、HBV基因变异以及α-干扰素抗病毒疗效均有一定的相关性,提示HBV基因分型有重要的临床意义.     

重型乙型肝炎患者血清乙型肝炎病毒全基因克隆及测序

目的建立重型乙型肝炎患者血清乙型肝炎病毒（HBV）DNA克隆并测序，从全基因水平分析HBV基因变异与重型乙型肝炎发病的关系。方法10例重型乙型肝炎患者血清提取HBV DNA，聚合酶链反应（PCR）扩增HBV全基因。PCR产物构建到PUCm-T载体上，转化至大肠杆菌感受态DH-5α细胞，经酶切鉴定，获得含3．2Kb HBVDNA的重组克隆菌，全基因测序，分析各读码框核苷酸和氨基酸变化。结果4例成功构建HBV DNA克隆，并完成全基因测序。其中3例在前C区发生G1896A变异，产生一个终止密码子，导致HBeAg缺失；1例在C启动子区1762、1764双位点出现突变；有多处点突变及缺失变异分布于PreS2区及C区已知细胞毒T淋巴细胞、B淋巴细胞和T淋巴细胞的细胞表位。结论该法可用于临床研究HBV病毒基因结构与重型乙型肝炎发病的关系，并为进一步研究其HBV基因功能奠定基础。     

未接受抗病毒治疗的慢性乙型肝炎患者多聚酶P基因YMDD变异检测

目的 了解未经拉米夫定及干扰素抗病毒治疗的慢性乙型肝炎患者中HBV多聚酶YMDD变异情况。方法 应用错配PCR扩增方法检测病人血清HBV的YMDD位点，选择65例病史超过半年以上、肝功能异常、HBV DNA阳性的慢性乙型肝炎患者。结果 在65例患者中，YMDD变异阳性6例(9．07％)，阴性59例，6例变异中2例为YIDD阳性，其中1例为YMDD野毒株和变异株混合存在，4例为YYDD阳性，其中1例为YMDD野毒株和变异株混合存在。结论 本检测方法简便、实用，在未经抗病毒治疗的慢性乙型肝炎患者中可存在YMDD变异株，其与野生株一样是自然存在的。     

Non-sequencing molecular approaches to identify preS2-defective hepatitis B virus variants proved to be associated with severe liver diseases

BACKGROUND/AIMS: PreS2-defective hepatitis B virus (HBV) variants may emerge during chronic HBV infection. These variants carry mutation(s) at the ATG-start-codon and/or in-frame deletion into the preS2 genomic region and are commonly detected by sequencing analyses. We evaluated the prevalence of these variants in a large series of chronic HBV infected patients through non-sequencing molecular approaches. METHODS: We examined HBV isolates from 110 HBV carriers: 15 were inactive carriers (IC); 50 had chronic hepatitis (CH); 25 were cirrhotics; 19 had hepatocellular carcinoma (HCC). The entire preS2 genomic region was amplified by PCR technique. The amplicons were processed: (A) through electrophoresis on acrylamide gel to reveal deleted genomes; (B) through electrophoresis on agarose gel after digestion by NlaIII enzyme that cuts the wild ATG-start-codon but not the mutated one. RESULTS: We detected preS2 variants in 56/110 cases (51%). In particular, we found preS2-defective mutants in 2/15 IC, 25/50 CH, 13/26 cirrhotics, and 16/19 HCC. The presence of these variants was thus significantly associated with active infection and liver disease (P<0.002). Moreover, among cases with liver disease preS2-mutants were more prevalent in HCC patients (P<0.02). CONCLUSIONS: Our non-sequencing molecular methods are sensitive and specific, and simplify the identification of all preS2 HBV variant forms. Infection by these variants is significantly associated with active infection and HCC.     

Impact of hepatitis B virus (HBV) preS/S genomic variability on HBV surface antigen and HBV DNA serum levels

To evaluate whether hepatitis B virus (HBV) preS/S gene variability has any impact on serum hepatitis B surface antigen (HBsAg) levels and to analyze the replication capacity of naturally occurring preS/S variants, sera from 40 untreated patients with HBV-related chronic liver disease (hepatitis B e antigen [HBeAg]-positive, n = 11; HBeAg-negative, n = 29) were virologically characterized. Additionally, phenotypic analysis of three different preS/S variant isolates (carrying a 183-nucleotide deletion within the preS1 region, the deletion of preS2 start codon, and a stop signal at codon 182 within the S gene, respectively) was performed. HBV infecting 14 (35%) patients had single or multiple preS/S genomic mutations (i.e., preS1 and/or preS2 deletions, preS2 start codon mutations, C-terminally truncated and/or "a" determinant mutated S protein). Presence of preS/S variants negatively correlated with HBsAg titers (r = -0.431; P = 0.005) and its prevalence did not significantly differ between HBeAg-positive and HBeAg-negative patients. No correlation was found between HBsAg and HBV DNA levels in patients infected with preS/S mutants, whereas a significant correlation was found between HBsAg and viremia levels (r = 0.607; P = 0.001) in patients infected with wild-type HBV strains. HepG2 cells replicating the above-mentioned three preS/S variants showed significant reduction of HBsAg secretion, retention of envelope proteins in the endoplasmic reticulum, less efficient virion secretion and nuclear accumulation of significantly higher amounts of covalently closed circular DNA compared with wild-type HBV replicating cells. CONCLUSION: In patients infected with preS/S variants, HBV DNA replication and HBsAg synthesis/secretion appear to be dissociated. Therefore, the use of HBsAg titer as diagnostic/prognostic tool has to take into account the frequent emergence of preS/S variants in chronic HBV infection.     

Quantitative DNA fragment analysis for detecting low amounts of hepatitis B virus deletion mutants in highly viremic carriers

Many variants of hepatitis B virus (HBV) with deletions in the viral genome have been identified. Some of these variants are indicator or even effector of a more severe course of hepatitis. These deletion mutants contribute a variable and sometimes very low proportion to the viral population. For early detection of small amounts of deletion mutants among a large number of wild-type genomes, we applied a new screening method designated quantitative fragment analysis (QFA). By QFA the whole viral genome can be scanned for the presence of deletions or insertions of >/=3 nucleotides representing more than 2% of the viral population. Using QFA we showed that an often described deletion of 8 nucleotides is packaged in viral capsids and not a polymerase chain reaction (PCR) artifact. QFA was applied to study the emergence of deletion mutants in a group of 18 pediatric patients who had been infected from a common source while being under multidrug cancer chemotherapy. All patients had developed a highly viremic asymptomatic HBV carrier state. In 3 of these patients 3 different kinds of HBV deletion mutants were found by QFA: 8 bp deletions within the core promoter, core gene deletions from 8 to 86 bp, and large deletions of up to 1,989 bp spanning the precore/core and the preS/S reading frames. PCR primers that specifically amplify deletion variants enabled the detection of additional patients harboring the investigated variant.     

Identification and characterization of genotype A and D recombinant hepatitis B virus from Indian chronic HBV isolates

AIM： To confirm the presence of recombination, fulllength hepatitis B virus （HBV） from chronic patients was sequenced and analyzed. METHODS： Full-length HBV genomes from 12 patients were amplified and sequenced in an automated sequencer. Phylogenetic analysis was carried out on full-length, Core and preS2/Surface regions using MEGA software. SimPIot Boot Scanning and amino acid sequence analysis were performed for confirmation of recombination. RESULTS： Eight patients were infected with genotype D strain; one patient with genotype A and three patients had genotype A and D recombination; two of them had cirrhosis and one had hepatocellular carcinoma. Phylogenetic analysis of core and preS2/surface regions separately showed evidence of genotype A and D recombination. The breakpoints of recombination were found to be at the start of preS2 and at the endof surface coding regions. CONCLUSION： We identified and characterized recombinant A and D genotype HBV in hepatitis B surface antigen （HBsAg）-positive patients.     

Prevalence of hepatocarcinoma-related hepatitis B virus mutants in patients in grey zone of treatment

BACKGROUND Antiviral treatment of patients with chronic hepatitis B(CHB) in the grey zone of treatment comands risk management in order to optimize the health outcome.In this sense,the identification of HBV mutants related with an increased risk of hepatocellular carcinoma(HCC) could be useful to identify subpopulations with potential indication of antiviral treatment.AIM To analyze the prevalence/persistence of hepatitis B virus(HBV) preS and basal core promoter(BCP)/precore/core variants associated to HCC development in CHB patients in the grey zone.METHODS Work was designed as a longitudinal retrospective study,including 106 plasma samples from 31 patients with CHB in the grey zone of treatment:Hepatitis B e antigen negative,HBV-DNA levels between 12-20000 IU/mL,normal or discordant transaminase levels during follow up and mild/moderate necroinflammatory activity in liver biopsy or Fibroscan(up to 9.5 kPa).Serum HBVDNA was tested using the Abbott Real Time HBV Assay and the BCP/precore/core and the hepatitis B surface antigen(HBsAg) coding regions were analyzed in positive samples by PCR/bulk-sequencing to identify the HCC related HBV mutants.RESULTS High-risk HCC related mutants were detected in 24(77%) patients:19(61%) in the BCP/precore/core,and 7(23 %) in the HBs Ag coding region(2 preS1 and 5 preS2 deletions).The prevalence of preS deletions was genotype-dependent:3/5(60%) patients with preS2 deletions and 1/2 with preS1 deletions were infected with the HBV-E genotype.Since HBV-E was the most prevalent in sub-Saharan patients,a correlation between preS deletions and ethnicity was also found:6/8(75%) sub-Saharan vs 1/19(5%) Caucasian patients had preS deletions(P=0.00016).Remarkably,this correlation was maintained in those patients infected with HBV-A,a minor genotype in sub-Saharan patients:2/2 patients infected with HBV-A from West Africa vs 0/6 of Caucasian origin had preS deletions.The HCC related variants were the major strains and persisted over time(up to 48 mo).Patients with preS deletions had a significant higher prevalence of F2 fibrosis stage than the negatives(57% vs 10%,P=0.0078).CONCLUSION HBV genetic analysis of selected populations,like sub-Saharans infected with HBV-E/A genotypes,will allow identification of subpopulations with risk of HCC development due to accumulation of high-risk HBV variants,thus commanding their increased clinical surveillance.     

Expression of preS antigens in serum during the chronic phase of hepatitis B virus infection

Serum patterns of preS gene encoded proteins during the chronic phase of hepatitis B virus infection and their relationship with hepatitis B virus deoxyribonucleic acid and hepatitis B 'e' antigen were investigated. The results indicate that the presence of preS1 and/or preS2 antigens in serum does not correlate with circulating hepatitis B virus deoxyribonucleic acid and hepatitis B 'e' antigen. It is, therefore, suggested that preS antigens cannot be regarded as specific markers of active viral replication in chronically hepatitis B virus infected patients.     

Quantitation of hepatitis B viremia and emergence of YMDD variants in patients with chronic hepatitis B treated with lamivudine

Hepatitis B viremia and emergence of hepatitis B virus (HBV) YMDD variants with reduced susceptibility to lamivudine were analyzed in patient sera from a phase II study of extended lamivudine therapy. Within 12 weeks, all patients exhibited a marked virologic response to lamivudine: >99% reduction (median 5 log decrease) in serum HBV DNA levels. Virus remained at >104 genomes/mL in 11 patients and decreased to <104 genomes/mL in the remaining 12 patients. In 10 patients, detectable YMDD variants emerged during the course of treatment. Six patients, including 3 with YMDD variants, experienced hepatitis B e antigen seroconversion while on lamivudine therapy or soon after its discontinuation. No patients with HBV DNA levels >104 genomes/mL seroconverted. Thus, patients who respond to lamivudine therapy with dramatic reductions in viral DNA level (to <104 genomes/mL) appear more likely to seroconvert than patients who do not achieve this level of HBV clearance.     

乙型肝炎病毒表面抗原一级结构多态性的初步研究

目的 研究慢性乙型肝炎患者体内乙型肝炎病毒（HBV）表面抗原一级结构的多态性。方法 设计特异性引物，自7例慢性乙型肝炎患者血清中扩增S基因全长或全基因组片段，TA克隆法克隆到T载体中，随机选择克隆测序。结果 共20个克隆被测序。20个克隆全S蛋白的总一致率仅为32．0％，13株全长为401氨基酸残基的克隆氨基酸一致效率为82．5％。患者血清中发现2株克隆编码截短型表面抗原中蛋白，在前S1或前S2的免疫决定区或可能的肝细胞结合部位均发现缺失突变。结论 慢性乙肝患者体内存在HBV准种群，病毒编码的截短型表面抗原中蛋白可为HBV诱导原发性肝癌提供一种途径，应加强对HBsAg一级结构多态性的研究。