Occult hepatitis B virus infection and lamivudine-resistant mutations in isolates from renal patients undergoing hemodialysis

Background and Aims:  Patients undergoing hemodialysis are at risk of infection with both hepatitis B virus (HBV) and hepatitis C virus (HCV). Occult HBV infection is usually associated with low levels of HBV and is frequently detected in HCV-infected patients. The aims of the present study were to compare the prevalence of occult HBV infection among anti-HCV-positive and anti-HCV-negative patients undergoing hemodialysis, and characterize the molecular patterns of HBV isolates from patients with occult infection.
Methods:  Serum samples from 100 patients negative for hepatitis B surface antigen undergoing hemodialysis, half of whom were positive for anti-HCV antibodies, were tested for the presence of HBV-DNA using semi-nested polymerase chain reaction (PCR). PCR products of the S gene were directly sequenced.
Results:  HBV-DNA was detected in 15 samples. There were no significant differences in HCV status, sex, age, time of dialysis, alanine aminotransferase levels or HBV serological markers between patients with or without occult HBV infection, with the exception of antibody to hepatitis B core antigen (anti-HBc)-only serological marker ( P  = 0.003). All six HBV isolates that could be sequenced were of genotype A/subgenotype A1. Four of these six HBV isolates contained mutations associated with lamivudine resistance in the DNA polymerase (two with L180M/M204V and two with rt173V/180M/204V) and a specific substitution (Y100C) in the HBV small surface protein.
Conclusions:  HBV isolates with the identified substitutions have the potential to spread silently by nosocomial transmission within the hemodialysis unit. These results have potential implications for the management of patients with occult HBV infection undergoing hemodialysis.     

拉米夫定耐药HBV毒株RT区变异分析

目的研究拉米夫定(LAM)治疗后出现HBV病毒学突破患者HBVRT区变异位点和变异类型。方法研究对象选自2004年4月至2007年3月在苏州大学附属第一医院门诊或住院治疗的慢性乙型肝炎患者,用聚合酶链式反应(PCR)方法扩增LAM治疗后出现HBV病毒学突破患者的血清HBVRT区基因,对PCR产物直接测序,用Chromas2.0软件分析HBVRT区基因的核苷酸和氨基酸差异、变异类型。结果109例患者在拉米夫定耐药后出现病毒学突破,其中94例出现拉米夫定耐药相关性变异,包括YMDD变异93例,单独rtA181T变异1例。13例(11.93%)患者经测序分析未发现YMDD变异,但用限制性内切酶片段长度多态性(RFLP)方法检测,均发现有YMDD变异。测序结果发生变异位点和出现频率:rtM204V/I93例(85.3%)、rtL180M51例(46.9%)、rtV173L/M7例(6.4%)、rtV207M/L/I4例(3.7%)、rtA181T4例(3.7%)、rtT184I/S/M2例(1.8%)、rtM250L2例(1.8%)。变异类型:rtM204V/I、rtA181T、rtM204V/I rtL180M、rtM204V/I rtL180M rtV173M等。结论拉米夫定耐药主要变异类型为rtM204V/I变异,常伴随rtL180M和rtV173L/M变异;少数拉米夫定耐药患者在阿德福韦和恩替卡韦治疗前即已产生阿德福韦和恩替卡韦耐药相关性变异。     

Hepatitis B virus genotypes and hepatitis B surface antigen mutations in family contacts of hepatitis B virus infected patients with occult hepatitis B virus infection

Background:  The association and profile of surface gene mutations with viral genotypes have been studied in patients with chronic hepatitis B virus (HBV) but not in subjects with occult HBV infection.
Aim:  This study aimed to investigate the association of surface gene mutations with viral genotypes in occult HBV infection.
Materials & Methods:  Of 293 family contacts of 90 chronic HBV index patients, 110 consented for the study. Of 110 subjects, 97 were hepatitis B surface antigen (HBsAg) negative. HBV genotyping was done using direct DNA sequencing. The S-gene was also sequenced in 13 chronic hepatitis B patients to serve as controls.
Results:  Twenty-eight (28.8%) of the 97 subjects had occult HBV infection. Bidirectional sequencing of partial S-gene was successful in 13 of them. Seven (53.8%) of the viral sequences are genotype A1, two (15.3%) each having genotypes D5&D2 and one each (7.6%) having D1&G genotypes. Seven (53.8%) of the 13 HBsAg positive patients, had genotype D&6 (46.1%) genotype A. A128V & T143M mutations were observed in 5 of 13 (38.4%) subjects and A128V & P127S in 2 of 13 (15.3%) patients ( P  = 0.385). A128V mutation was seen in two (15.3%) subjects with D2 genotype, while T143M mutation was seen in three (23.07%) subjects with A1genotype. At aa125, three (23.07%) subjects with D5 genotype had methionine instead of threonine. There were wild type sequences in five (38.4%) subjects, one each of D1, G genotypes (20%) and four A1 (80%) genotypes. None of the subjects had G145R mutation.
Conclusions:  Occult HBV infection may be common in household contacts of chronic HBV infected patients. Equal prevalence of A&D sub-genotypes was present in occult HBV subjects and in chronic HBV patients. Mutations of the S-gene are genotype specific in both occult as well as chronic HBV infection.     

拉米夫定治疗前后乙型肝炎病毒YMDD变异的相关因素分析

目的 了解遵义地区HBV基因型以及拉米夫定治疗前后发生YMDD变异的相关因素,及早进行拉米夫定疗效及耐药的预测. 方法 53例慢性乙型肝炎患者分别在口服拉米夫定前及治疗后3、6、12、18、24个月进行血清HBV DNA定量、乙型肝炎标志物、ALT、AST、总胆红素,白蛋白的检测.同时在接受拉米夫定治疗前采用基因测序法检测HBV基因型及YMDD变异株,治疗后HBV DNA定量下降又反弹升高,且血清HBV DNA＞1×104拷贝/ml时,再次进行YMDD变异株检测.率的比较用卡方检验及确切概率法,两组均数之间比较采用独立样本t检验,有序变量之间的比较采用秩和检验.结果 遵义地区的HBV基因型由B、C及B+C基因型构成.拉米夫定治疗后18例检出YMDD变异株,用药1年和2年的变异率分别为15.1%和34.0%.HBV突变类型有rtL180M/M204V、rtL180M/M204I、rtM204I和rtL180M四种,其中C区rtM204V全部合并rtL180M突变(100%),C基因型中rtL180M/M204V联合突变及rtL180M/M204I联合突变明显高于B基因型(77.8%比25.0%及22.2%比12.5%);C基因型中未见点突变,而rtM204I、rtL180M的点突变仅见于B基因型.YMDD变异与未变异组性别、民族、乙型肝炎家族史及HBeAg情况差异无统计学意义(P＞0.05),病程≥2年组和年龄＜35岁组变异率明显升高(X2值分别为4.707和5.853,P值均＜0.05).不同HBV DNA滴度患者YMDD变异率差异无统计学意义(X2=0.801,P＞0.05),但HBV DNA＜105拷贝/ml者未发现YMDD变异.结论 拉米夫定治疗后YMDD变异可能与HBV基因型及P基因突变类型有关,并随治疗时间的延长而增加.为了减少YMDD变异的发生,应选用病程短、HBV DNA水平较低、肝损害较重的患者进行拉米夫定治疗,有条件的应检测HBV基因型.     

Hepatitis B virus with the rtL80V/I mutation is associated with a poor response to adefovir dipivoxil therapy

Background/Aims: Lamivudine (LAM) resistance is frequently associated with various types of genomic changes in hepatitis B virus (HBV)‐DNA including YMDD mutations (rtM204V/I). We intended to examine the effects of these genotypic variants on the antiviral efficacy of adefovir dipivoxil (ADV) therapy. Methods: A total of 97 chronic hepatitis B (CHB) patients with YMDD mutants who had been treated with ADV for >12 months were analysed. Mutations of the entire polymerase domain of HBV were determined by direct sequencing. Results: All the 97 patients had genotype C HBV associated with rtM204V/I mutations; 63 (65%) rtM204I, 27 (28%) rtM204V and seven (7%) both. The rtL80V/I and rtL180M variants were identified in 66 (68%) and 67 (69%) patients respectively. The rtM204I and rtM204V variants were strongly associated with rtL80V/I and rtL180M respectively (P<0.01). There was no difference in antiviral response at 12 months after ADV therapy between patients in relation to the type of YMDD mutation or the presence of rtL180M. However, interestingly, after ADV therapy for 12 months, patients with rtL80V/I achieved a much smaller reduction in serum HBV‐DNA titre than those without it (mean, ?3.43 vs. ?4.43 log₁₀ copies/ml; P=0.018). In addition, patients with rtL80V/I had lower rates of undetectable HBV‐DNA (20 vs. 26%), alanine aminotransferase normalization (70 vs. 81%) and HBeAg loss (16 vs. 26%) than those without it, although none of these differences was statistically significant. Conclusions: These results provide evidence that rtL80V/I variants of HBV may be associated with a poor antiviral response to ADV in CHB patients with YMDD mutants.     

拉米夫定治疗无良好应答患者乙型肝炎病毒P区突变与基因型的关系

目的 观察拉米夫定治疗后无良好应答的慢性乙型肝炎患者HBV P区变异情况与基因型的关系.方法 对631例拉米夫定治疗后无良好应答的慢性乙型肝炎患者进行研究.通过荧光定量PCR或核酸测序确定HBV基因型,直接测序观察P区突变,实时荧光定量PCR方法检测患者病毒载量,比较不同基因型患者的HBV DNA水平及HBV P区变异情况.计量资料采用成组设计资料t检验,计数资料采用x~2检验或Fisher精确检验.结果 631例慢性乙型肝炎患者中,B基因型HBV感染者272例,C基因型感染者359例,C基因型感染者患者年龄为(39.1±11.4)岁,明显大于B基因型感染患者的(33.7±9.7)岁(t=-6.55,P<0.01).C基因患者病毒载量为(5.96±1.22)log_(10)拷贝/ml,高于B基因型患者的(5.58±1.21)log_(10)拷贝/ml,t=-2.01,P<0.05.A181V/T变异在C基因型的发生率高于B基因型(0.4%比5.3%,χ~2=12.23,P<0.01),M204I/V,L180M、T184A/G/I/S、S202G/I和V173L变异发生率在B、C基因型之间差异无统计学意义(P值均>0.05).M204I在B基因型的发生率为20.6%,高于C基因型的13.9%(χ~2=4.91,P<0.05);M204V和M201Ⅳ变异在B、C基因型中的发生率差异无统计学意义(χ~2值分别为1.70和2.21,P值均>0.05).拉米夫定耐药发生率在B、C基因型间差异无统计学意义(χ~2=0.00,P>0.05).结论 拉米夫定常见耐药位点在B、C基因型之间无明显差异,但是C基因HBV感染患者病毒载量高于B基因型HBV感染患者;M204I变异在B基因型中出现频率高于C基因型,拉米夫定加用或改用阿德福韦酯后可能会使A181V/T变异在C基因型出现的概率高于B基因型;年龄、免疫因素和非常见位点的变异或许是影响拉米夫定疗效的重要因素.     

Four‐year study of lamivudine and adefovir combination therapy in lamivudine‐resistant hepatitis B patients: influence of hepatitis B virus genotype and resistance mutation pattern

Summary. To investigate the efficacy of long‐term lamivudine (3TC) and adefovir dipivoxil (ADV) combination therapy in 3TC‐resistant chronic hepatitis B virus (HBV) infected patients, we analysed 28 3TC‐resistant patients treated with the combination therapy during 47 months (range, 9–75). At 12, 24, 36, and 48 months, the rates of virological response with undetectable HBV DNA (≤2.6 log copies/mL) were 56, 80, 86, and 92%, respectively. Among 17 hepatitis B e antigen (HBeAg)‐positive patients, HBeAg disappeared in 24% at 12 months, 25% at 24 months, 62% at 36 months, and 88% at 48 months. When HBV genotypes were compared, patients with genotype B achieved virological response significantly more rapidly than those with genotype C (P = 0.0496). One patient developed virological breakthrough after 54 months, and sequence analysis of HBV obtained from the patient was performed. An rtA200V mutation was present in the majority of HBV clones, in addition to the 3TC‐resistant mutations of rtL180M+M204V. The rtN236T ADV‐resistant mutation was observed in only 25% clones. In vitro analysis showed that the rtA200V mutation recovered the impaired replication capacity of the clone with the rtL180M+M204V mutations and induced resistance to ADV. Moreover, rtT184S and rtS202C, which are known entecavir‐resistant mutations, emerged in some rtL180M+M204V clones without rtA200V or rtN236T. In conclusion, 3TC+ADV combination therapy was effective for most 3TC‐resistant patients, especially with genotype B HBV, but the risk of emergence of multiple drug‐resistant strains with long‐term therapy should be considered. The mutation rtA200V with rtL180M+M204V may be sufficient for failure of 3TC+ADV therapy.     

Drug-Resistance Associated Mutations in Polymerase (P) Gene of Hepatitis B Virus Isolated From Malaysian HBV Carriers

Background:

Mutations in the polymerase (P) gene of hepatitis B virus are often associated with drug resistance. The pattern of mutations varies geographically, thus giving rise to genotypes diversity.

Objectives:

This study was carried out to detect mutations in P gene of hepatitis B virus isolated from Malaysian HBV carriers.

Materials and Methods:

A total of 58 sera samples were analyzed by PCR and sequencing, of which the P gene of isolated HBV was successfully amplified and sequenced from 40 samples.

Results:

Genotyping of these samples revealed that the predominant genotype was genotype C (22/40, 55.0%), followed by genotype B (17/40, 42.5%), and only 1 sample showed genotype D (2.5%). A number of significant drug resistant mutations were found in five patients including S202I, N236T, M250L, L180M/V, M204I, A181T, T184G, M250V, and V173L. Of these, L180M/V and M204I were most frequently detected (80%) and associated with lamivudine in combination with emtricitabine and telbivudine drug resistance. Association with age, sex, and clinical symptoms revealed that these patients were all male, mid to elderly age and almost all hadcirrhotic liver disease.

Conclusions:

Detection and surveillance of the significant sites of mutations in HBV is crucial for clinicians to decide on the choice of antiviral treatment and further management of hepatitis B carriers.     

乙型肝炎病毒基因型、YMDD变异与拉米夫定治疗后HBV DNA反弹关系的研究

目的探讨HBV基因型、YMDD变异与拉米夫定抗病毒治疗后HBV DNA反弹的关系。方法应用多引物对巢式PCR法、PCR-序列分析法检测拉米夫定治疗的27例乙型肝炎患者和19例从未用过抗病毒治疗的患者HBV基因型和P区（YMDD）的突变位点。结果在27例HBV DNA反弹的患者中，13例（48．15％）检出YMDD变异，而对照人群无YMDD变异（P〈0．05）。YMDD变异的位点为rtM204V／I（C区）±rtL180M（B区）；在治疗组YMDD变异的患者中，B、C基因型构成比（46．15％和59．26％）与对照组（53．85％和68．42％）比较无显著性差异（P〉0．05）。结论YMDD变异是拉米夫定治疗后出现耐药导致HBV DNA反弹的主要原因；YMDD变异的常见位点依然为rtM204V／I（C区）±rtL180M（B区）；YMDD变异在B、C基因型病人中无差别。     

740例 HBV 感染者血清 HBV 逆转录酶区耐药位点分析

目的：了解乙型肝炎病毒（HBV）感染者 HBV 基因型的构成状况及 HBV P 区基因变异的特点。方法对2010年8月～2011年10月送检的740份 HBV 感染者血清,采用 ABI 基因测序仪检测 HBV 耐药位点和基因型,应用 SPSS15.0软件进行统计分析。结果在740例 HBV 感染者中,检出 HBV B 基因型40例（5.41%）,C 基因型695例（93.92%）,D 基因型5例（0.68%）;与拉米夫定、阿德福韦酯和恩替卡韦耐药明确相关的位点突变377例（50.95%）,其中195例（51.72%）患者既往有明确的应用核苷（酸）类似物（NA）史,在这195例发生耐药的患者中,B基因型12例,C 基因型183例,两基因型间耐药发生率无明显差异,他们中包括 CHB 患者118例,肝硬化患者77例,主要耐药变异模式为 M204V＋L180M、M204I、M204I＋L180M 和 A181V,两组间 ALT、HBV DNA 载量和主要耐药变异模式检出率均无统计学差异;HBV DNA 载量是影响 NA 耐药的相关因素（x2=0.496,P〈0.001）,但耐药与年龄、性别、疾病严重程度（CHB 或肝硬化）和 ALT 水平无显著性相关;此外,本文还检出多处未知变异位点,如 rt64、rt126、rt178和 rt129等。结论核苷（酸）类似物的使用将伴随病毒变异的发生,其耐药基因变异位点具有一定的特点及规律性,动态监测 HBV DNA 载量对早期发现耐药有一定的价值。     

慢性乙型肝炎患者抗病毒治疗中的病毒准种演变

目的 探讨拉米夫定耐药后换用恩替卡韦补救治疗的慢性乙型肝炎患者的病毒准种演变.方法 提取1例慢性乙型肝炎患者治疗中的7个不同时间点(0、24、48、60、72、96、152周)血清中的HBV DNA,巢式聚合酶链反应法扩增HBV DNA聚合酶基因逆转录酶区,克隆测序法对逆转录酶区氨基酸替换形式及准种分布进行分析,并采用扩增耐药突变系统聚合酶链反应法对患者病毒种群中野毒株与病毒总量进行定量检测.结果 患者在治疗过程中主要存在rtM204V、rtL180M+rtM204V和rtM204I 3种拉米夫定耐药相关的病毒株变异形式,各病毒株所占比例不断发生变化,基线时HBV野毒株为优势病毒株,在病毒学突破时,种群中全部为耐药突变株;换用恩替卡韦治疗后,随着病毒载量的下降,拉米夫定耐药突变株被抑制,野毒株在种群中比例逐渐上升,并成为优势病毒株(79.3%).扩增耐药突变系统聚合酶链反应检测结果显示,在基线和发生病毒学突破时,野毒株在种群中的比例分别为68.55%和0.21%,换药治疗后24周,野毒株比例开始上升,此后野毒株占种群的比例波动于16.01%～26.93%.结论 慢性乙型肝炎患者在核苷(酸)类药物序贯治疗过程中,HBV种群的准种分布一直处于动态变化中.不同的HBV准种演变模式可能在恩替卡韦补救治疗中对恩替卡韦耐药发生的作用也不相同.

Abstract：

Objective To investigate the evolution of hepatitis B virus (HB V) quasispecies in one patient during lamivudine (LAM) monotherapy and switching to entecavir (ETV) rescue treatment. Methods Serum samples were taken at seven different time points during antiviral therapy (0, 24, 48, 60, 72, 96,152 weeks, respectively), the HBV DNA polymerase gene was amplified, cloned and sequenced to analyze the amino acid substitutions within HBV DNA polymerase gene and distribution of virus quasispecies. Quantitative detection of the HBV wild strains and total virus was performed by amplification refractory mutation system real-time PCR (ARMS-PCR). Results Three mutation patterns detected during antiviral therapy in the patient: rtM204V, rtM204V+rtL180M and rtM204I. The HBV quasispecies were found always in dynamic variation. The HBV populations were completely replaced with the LAM-resistant variants when the viral breakthrough was encountered during LAM monotherapy. Interestingly, the wild-type variants presented gradually dominant (79.3%) with the decline of HBV DNA load after switching to ETV rescue administration. ARMS-PCR results showed that the wild-type variants account ed for 68.55% of the HBV populations at baseline and this proportion declined to 0.21% when the viral breakthrough emerged under LAM therapy. The wild-type variants gradually increased from week 24 after switching to ETV rescue therapy and the proportion of HBV wild-type variants in the population fluctuated between 16.01% to 26.93%. Conclusions The distribution of virus quasispecies were always in dynamic variation during sequential therapy with nucleotide analogs in chronic hepatitis B patients. Different patterns of dynamic HBV quasispecies may have different contribution in ETV resistance in LMV refractory patients with ETV administration.     

YMDD mutations and genotypes of hepatitis B virus in northern China

The objective of this research was to determine the relationship between YMDD mutations and the genotypes of hepatitis B virus (HBV) during lamivudine treatment. HBV genotypes were determined by nested PCR with 6 pairs of HBV genotype-specific primers (A to F) in serum specimens from 142 hepatitis B patients receiving lamivudine antiviral therapy. YMDD mutations were detected by fluorescent hybridization bioprobe PCR and melting curve assay (FH-PCR-MC). Among 142 serum specimens, 13 samples were genotype B (9.2%), 125 samples were genotype C (88%), 4 samples were genotype D (2.8%), and 80 YMDD mutations were found. The YMDD mutation rates were 69.2 and 54.4% in genotype B and genotype C, respectively. There was no significant difference in the YMDD mutation rate between genotypes B and C. Nine genotype B sera with YMDD mutations were found, including 2 YIDD mutations and 7 YVDD (M + V) mutations. Sixty-eight genotype C sera with YMDD mutations were found, including 34 mutations I (M + I) and 17 mutations V (M + V). There was a significant difference in the YMDD mutation types between genotypes B and C. Our results suggested that the YMDD mutation rate was 56.3% in patients treated with lamivudine for 2-4 years. YIDD was the main mutation type. The YMDD mutation rate showed no significant difference between HBV types B and C (P > 0.05), while the YMDD mutation types showed a significant difference between HBV types B and C in Northern China (chi2 test = 4.6, P < 0.05).     

Activity of adefovir dipivoxil against all patterns of lamivudine-resistant hepatitis B viruses in patients

One hundred and thirty-one post-liver transplantation patients with chronic hepatitis B and failing lamivudine therapy with detectable serum hepatitis B virus (HBV) deoxyribonucleic acid by hybridization assays or > or =1 x 10(6) copies/mL by polymerase chain reaction, and elevated alanine transaminase levels despite continuous lamivudine, were enrolled in an open-label study of adefovir dipivoxil. The B and C domains of HBV polymerase were sequenced for baseline samples to determine the presence of lamivudine resistance mutations. The results showed that 98% of the samples had tyrosine-methionine-aspartate-aspartate (YMDD) mutations, indicating a strong correlation between the above clinical definition of lamivudine treatment failure and the presence of YMDD mutations. In addition to the rtM204V/I and the rtL180M mutations, the mutation rtV173L was identified in 19% of patients. Four major patterns of lamivudine-resistant HBV were identified: rtL180M + rtM204V (60%), rtV173L + rtL180M + rtM204V (19%), rtM204I (9%) and rtL180M + rtM204I (9%). Treatment with adefovir dipivoxil showed similar antiviral efficacy in patients with lamivudine-resistant virus from all four patterns.     

Hepatitis B virus genotype distribution and its lamivudine-resistant mutants in HIV-coinfected patients with chronic and occult hepatitis B

Hepatitis B virus (HBV) genotypes were examined in HIV-infected patients with chronic and occult HBV infection. From a total population of 593 HIV-infected patients, 22 individuals (prevalence 3.7%) were found to be HBsAg while 72 (12.1%) were found to be anti-HBc alone. From them, 20 and 4 were HBV DNA positive, respectively. These last four patients are therefore considered to be HBV infected in an occult form. The genotypes could be determined in all 24 HBV-infected patients. HBV-A was the most common (20/24; 83.3%), followed by HBV-D (2/24; 8.3%) and HBV-F (1/24; 4.2%). The remaining sample exhibited mixed infection involving genotypes A and D as pure ones, thus also forming part of three intergenotypic recombinant forms exhibiting different mosaic S gene patterns. The sexual route of transmission was predominant among HBV genotype A-infected patients. Among the 24 HBV DNA-positive patients, point mutations related to lamivudine resistance were found in four strains. These viral strains showed a methionine-to-valine substitution at codon 204 (rtM204V) in association with an upstream B-domain change at rtL180M. Additionally, two of them exhibited the additional rtV173L mutation. The value of HBV molecular monitoring including both HBV viral genomic characterization and genotypic resistance profile in HIV-HBV-coinfected individuals is discussed.     

Hepatitis B virus genotypes and subgenotypes in China

Eight Hepatitis B virus (HBV) genotypes (A to H) have been identified based on an intergenotype divergence of 8% or more in the entire nucleotide sequence. Subgenotypes have also been identified in different HBV genotypes. As a highly endemic area for HBV infection, the prevalence of chronic HBV infection in China is between 8 and 20% of the general population. Genotypes B and C were identified as the most common HBV strains and account for approximately 95% of Chinese patients. Further study confirmed all genotype B strains belong to subgenotype Ba. Two of genotype C subgenotypes, C1 (Cs) and C2 (Ce), were found in China and they showed different geographic distributions. Genotype A was very rarely found, while genotypes E, F, G and H have not beenreported until now. Two types of HBV C/Drecombinant viruses have been identified in west China and distinct geographic and ethnic distributions were observed. Significant differences were observed ( P  < 0.001) in the prevalence of A1896 and T1762/A1764 mutations among HBV Ba, C1 and C2 subgenotypes in Chinese patients. Accumulating evidence showed the response rate to antiviral therapy in Chinese patients is higher in genotype B than genotype C patients on interferon treatment, but no difference was observed on nucleoside/nucleotide analog treatment.