Evolution of wild type and mutants of the YMDD motif of hepatitis B virus polymerase during lamivudine therapy

BACKGROUND AND AIM: Long-term lamivudine treatment for chronic hepatitis B virus (HBV) infection induces the emergence of lamivudine resistant HBV YMDD mutant strains. The aim of the present study was to observe the clone evolution of YMDD wild type and mutant strains in pretreatment and post-treatment samples during lamivudine therapy and analyze their clinical significance. METHODS: Ten serum samples (five before and five after 48 weeks of therapy) obtained from five patients chronically infected with HBV and treated with lamivudine were studied. Part of the HBV polymerase gene flanking the YMDD motif was sequenced after polymerase chain reaction (PCR) amplification. Meanwhile, 20-24 clones were selected at random from each sample and YMDD wild type and mutant strains were detected by real-time fluorimetry PCR established in our laboratory. RESULTS: The YMDD mutants were not detectable in all five patients before treatment and were found in four patients after 48 weeks of therapy by sequencing directly on PCR products. Analysis of individual clones showed that the ratios of mutant strains in each of the five patients were 0, 9.5, 0, 4.5 and 5.6%, respectively, before therapy and 100, 100, 65, 100 and 0%, respectively, after 48 weeks of therapy. M552I was detected before therapy in one patient but M552V became the domain strain after therapy. Until 52 weeks of therapy, serum HBV DNA and alanine aminotransferase (ALT) breakthrough were found in two of the four patients with YMDD mutations. The fifth patient experienced breakthrough of ALT but HBV DNA remained undetectable. CONCLUSIONS: The mutant strains of YMDD motif of HBV polymerase could be found in patients before lamivudine treatment, indicating that antiviral therapy allows the rapid selection of resistant strains. The replication ability of the M552V mutant strain might be stronger than that of the M552I mutant strain.     

拉米夫定治疗慢性乙型肝炎发生YMDD变异的研究

目的探讨拉米夫定治疗慢性乙型肝炎（CHB）发生YMDD变异的临床意义。方法分别用荧光定量PCR、ELISA检测72例用拉米夫定治疗的CHB患者治疗前（0个月）、治疗中（9、12、18个月）YMDD变异的情况、HBVDNA定量水平、两对半等指标。结果72例CHB患者中,拉米夫定治疗前未检查出YMDD变异,治疗9、12、18个月分别检出YMDD变异8例（11.1%）,17例（23.6%）,28例（38.9%）,随治疗时间的延长,YMDD变异率升高（P〈0.05）。另外用药前HBVDNA定量〉108copies/ml与HBVDNA定量〈108copies/ml相比YMDD变异率显著升高（P〈0.005）。HBeAg阳性组与HBeAg阴性组的患者在不同治疗时间YMDD变异率,差异无显著性（P〉0.05）。结论YMDD变异的发生随治疗时间的延长而增加。血清病毒载量可作为应用拉米夫定治疗YMDD变异产生的早期预测指标。     

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。     

拉米夫定抗乙型肝炎病毒感染中YMDD变异类型及时间研究

目的 研究拉米夫定抗乙型肝炎病毒(HBV)感染中P基因发生YMDD变异的类型和出现时间。方法 取拉米夫定治疗过程中HBV DNA由阴性再次转为阳性33例患者及HBV DNA始终保持阳性达一年或一年以上2例患者的血清,经PCR扩增HBV的P基因,对扩增产物进行测序及用3个限制性内切酶分析HBVP基因的YMDD变异。 结果 14例出现YMDD变异,其中6例YVDD变异,4例YIDD变异,3例YI/VDD混合变异,1例YI/MDD变异。变异出现时间平均为(11.07±3.65)个月,最短5个月,最长7个月。其中YIDD为(10.00±1.41)个月,YVDD为(11.67±4.41)个月,YI/VDD为(13.33±3.31)个月,三种变异类型的出现时间差异无显著性(F=0.543,P>0.05)。3例YMDD变异后拉米夫定加量至200mg/d,未能消除变异病毒。 结论 拉米夫定抗HBV感染后变异有多种形式,包括YIDD、YVDD、YI/VDD、YI/MDD。变异发生时间一般在治疗后(11.07±3.65)个月。变异类型与用药时间无关。     

YMDD耐药变异与HLA等位基因多态性的相关性

目的：初步探讨慢性乙型肝炎(CHB)患者拉米夫定治疗中YMDD变异与HLA-A,B,DRB1各位点等位基因分布频率的相关性．方法：对142例CHB患者,采用荧光标记杂交双探针PCR融解曲线法(FH-PCR-MC)检测血浆HBV YMDD变异；对其中56例患者的外周血白细胞,采用序列特异性引物/聚合酶链式反应(PCR-SSP)技术检测人类白细胞表面抗原等位基因(HLA-A-B,DRB1)分型．结果：在用拉米夫定治疗的142例CHB患者中,YMDD变异率为56．3％．HLA-B~*58和DRB1~*03等位基因分布频率在YMDD变异组与YMDD野生组比较有显著性降低(0．013 vs 0．094,P=0．036；0．000 vs 0．063,P=0．024)；HLA-A~*30等位基因分布频率在YIDD组明显增高,与YVDD组比较差异显著(0．158 vs 0．024,P=0．034)；HLA-A~*33等位基因分布频率在YVDD变异组明显增高,与YIDD变异组比较差异显著(0．119 vs 0．000,P=0．028)．结论：YMDD耐药变异与HLA等位基因多态性有一定相关性．携有HLA-B~*58和DRB1~*03等位基因的个体感染的HBV可能不易发生YMDD变异；携有HLA-A~*30等位基因的个体感染的HBV可能易发生YIDD变异：携有HLA-A~*33等位基因的个体感染的HBV可能易发生YVDD变异．     

Low rate of YMDD motif mutations in polymerase gene of hepatitis B virus in chronically infected patients not treated with lamivudine

Background Lamivudine is used for the treatment of chronic hepatitis B (CH-B), and exhibits excellent antiviral activity. However, longterm administration increases the likelihood of the emergence of resistant viruses, with an accompanying relapse of hepatitis. However, recent studies have reported lamivudine-resistant viruses in patients with CH-B before such treatment. The aim of this study was to investigate whether YMDD mutants occur in nature.Methods The existence of lamivudine-resistant viruses was examined in 20 asymptomatic carriers of hepatitis B virus (ASC), 10 patients who lost hepatitis B surface antigen (HBsAg) during follow-up and in 20 lamivudine-treated patients with and without breakthrough hepatitis. Both polymerase chain reaction (PCR) restriction fragment length polymorphism and SMITEST hepatitis B virus (HBV)-YMDD mutation detection methods were used to detect resistant viruses.Results No YMDD mutants were detected in the sera of the 20 ASC at the initial and final medical examinations, nor were YMDD mutants detected in sera collected at the initial medical examination, about 6 months before, or immediately after the loss of HBsAg in the 10 patients. In the 20 patients treated with lamivudine, YMDD mutants were not detected in any of them before treatment, whereas mutants were detected in the sera of 10 patients during treatment.Conclusions Our results suggest that lamivudine-resistant YMDD mutant viruses were present in a few patients with HBV infection who before they have been treated with lamivudine.     

YMDD mutations in patients with chronic hepatitis B untreated with antiviral medicines

AIM: To polymerase P region (YMDD) mutations of hepatitis B virus gene (HBV DNA) in patients with chronic hepatitis B (CHB) untreated with antiviral medicines and to explore its correlation with pre-c-zone mutations, HBV genotypes and HBV DNA level, and to observe its curative effect. METHODS: A total of 104 cases (38 cases in group of familial aggregation and 66 cases in group of non-familial aggregation) were randomly chosen from 226 patients with CHB who did not receive the treatment of lamivudine (LAM) and any other antivirus drugs within the last one year. Their serum YMDD mutations were detected by microcosmic nucleic acid and cross-nucleic acid quantitative determination, HBV genotypes by PCR-microcosmic nucleic acid crossELISA, HBV DNA quantitative determination and fluorescence ration PCR analysis, hepatitis B virus markers (HBVM) by ELISA. LAM was taken by 10 patients with YMDD mutations and its curative effect was observed. RESULTS: Twenty-eight cases (26.9%) had YMDD mutations, of them 11 cases (28.9%) were in familial aggregation group (38 cases) and 17 cases (25.8%) in nonfamilial aggregation group (66 cases) with no significant difference between the two groups. Twenty-seven point one percent (16/59) cases were positive for HBeAg YMDD mutations, and 26.7% (12/45) cases were negative for HBeAg and positive for anti-HBe. There was also no significant difference between the two groups. Different YMDD incidence rate existed in different HBV genotypes. HBV DNA level did not have a positive correlation with the incidence of YMDD mutations. LAM was effective for all patients with mutations. CONCLUSION: Wild mutant strains in HBV and their incidence rate have no significant difference between familial aggregation and non-familial aggregation. It may have no significant relationship between YMDD mutations and pre-c-zone mutations. HBV DNA level may not have a positive correlation with YMDD mutations. LAM is clinically effective for CHB patients with YMDD mutations.     

慢性乙型肝炎病毒感染者病毒YMDD的自然变异

目的 了解慢性HBV感染患者外周血HBV YMDD自然变异情况及其影响因素.方法 采用引物特异性实时荧光PCR法检测慢性HBV感染者外周血HBV YMDD变异情况,并对影响YMDD自然变异检出率的可能因素进行单因素及多因素分析.根据不同资料分别采用χ~2检验、Fisher's确切概率法、t检验、秩和检验及Logistic回归分析进行统计学处理. 结果在196例未经抗病毒治疗的慢性HBV感染者中,检出存在YMDD自然变异株感染者21例(10.70%),其中YVDD阳性20例,YIDD阳性例1变;变异毒株占总病毒株超过50%者1例,25%～500者5例,9%～25%者15例.B基因型HBV感染病例中YMDD变异株的检出率(20.00%,12/60)显著高于C基因型HBV感染病例(7.38%,9/122),χ~2=6.28,P<0.05.患者性别、年龄、HBeAg状态、HBVDNA载量、疾病状态、病毒感染时间对YMDD自然变异株的检出率无显著影响. 结论 在未经抗病毒治疗的慢性HBV感染者中存在HBV YMDD自然变异;YMDD自然变异的发生率与患者性别、年龄、HBeAg状态,HBV DNA载量、疾病状态、感染时间无显著相关性.B基因型较C基因型HBV更易出现YMDD自然变异.     

Interferon therapy for flare-up of hepatitis B virus infection after emergence of lamivudine-induced YMDD motif mutant

A 61-year-old man with chronic hepatitis B was treated with interferon (IFN)-α for flare-up after the emergence of a lamivudine-induced YMDD motif mutant. The YMDD mutant emerged 13 months after the initiation of lamivudine therapy. Despite this, lamivudine therapy was continued. Acute exacerbation occurred 25 months after the emergence of the YMDD mutant. Treatment with IFN-α resulted in rapid loss of hepatitis, B virus DNA, resolution of hepatitis, and clinical recovery. Received: December 27, 1999 / Accepted: April 28, 2000     

拉米夫定加肝络欣治疗慢性乙型肝炎疗效及对YMDD变异的影响

观察拉米夫定加肝络欣联合治疗慢性乙型肝炎的疗效及对慢性乙型肝炎病毒P基因(YMDD)变异的影响。收集乙型肝炎病毒(HBV)HBeAg、HBVDNA阳性的慢性乙型肝炎患者6 7例,分为拉米夫定加用肝络欣组(A组)、单用拉米夫定组(B组)。分别检测血清HBeAg、抗-HBe、HBVDNA ,肝脏生化指标和基因YMDD变异。在治疗5 6周时,拉米夫定联合肝络欣组HBeAg/抗-HBe转换率(39. 4 % ) ,优于拉米夫定组(P <0 .0 5 )。HBVDNA阳性率及YMDD变异率都比拉米夫定组低(P <0 . 0 5 )。拉米夫定联合肝络欣能在一定程度上提高治疗慢性乙型肝炎的疗效并可减少YMDD变异。     

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。     

The HBV DNA cutoff value for discriminating patients with HBeAgnegative chronic hepatitis B from inactive carriers

Background

Patients with HBeAg-negative chronic hepatitis B (CHB) has a significantly different prognosis than inactive carriers; there is however, no reliable strategy for accurately differentiating these two disease conditions.

Objectives

To determine a strategy for discriminating patients with HBeAg-negative CHB from inactive carriers.

Materials and Methods

Consecutive inactive carriers (i.e. HBeAg-negativity, anti-HBe-positivity, normal ALT levels, and HBV DNA < 2000 IU/mL) were enrolled. HBV reactivation was defined as the elevation of the HBV DNA level to ≥ 2000 IU/mL. Patients were classified into true inactive carriers when their HBV DNA levels remained at < 2000 IU/mL or false inactive carriers when their HBV DNA levels increased to ≥ 2000 IU/mL during the first year.

Results

The Mean ± SD age of 208 inactive carriers (140 males) was 47.7 ± 12.6 years. The Mean ± SD serum ALT and HBV DNA levels were 22.8 ± 8.6 IU/L and 360 ± 482 IU/mL, respectively. HBV reactivation developed in 41 (19.7%) patients during the first year. Baseline HBV DNA and ALT levels differed significantly between true inactive and false inactive carriers. The AUROCs of the baseline ALT and HBV DNA levels for predicting a false inactive carrier were 0.609 and 0.831, respectively. HBV reactivation developed more often in patients with a baseline HBV DNA level of ≥ 200 IU/mL than in those with a baseline HBV DNA level of < 200 IU/mL during a Mean ± SD follow-up of 622 ± 199 days.

Conclusions

The HBV DNA level was useful for discriminating patients with HBeAg-negative CHB from true inactive carriers. The follow-up strategies applied to inactive carriers need to vary with their HBV DNA levels.     

慢性乙肝YMDD变异患者肝纤维化指标、血清标志物的检测及意义

探讨慢性乙肝患者(CHB)发生YMDD变异后肝纤维化指标及血清标志物的变化意义.检测接受拉米夫定治疗285例CHB患者YMDD变异情况,根据结果分为无突变组和突变组;又各分为继续使用拉米夫定治疗组和未继续治疗组;并测定各组乙肝病毒拷贝数(HBV-DNA)、乙肝两对半(HBV M)、常规肝功能指标、透明质酸(HA)、Ⅲ型前胶原(PCⅢ)、Ⅳ型胶原(CIV)水平.结果显示285例患者中发生YMDD突变144例,以YIDD型最常见;突变组HBeAg阳性率、HBV-DNA水平高于无突变组(P＜0.01、P＜0.05);无突变病例中继续治疗组CIV、PCⅢ、HBV-DNA水平比未继续治疗组出现下降(P＜0.01、P＜0.05).YMDD突变组HBeAg阳性率、病毒拷贝数高于无突变组,而纤维化指标无差异;继续使用拉米夫定治疗,可改善无突变组患者肝组织纤维化.     

拉米夫定治疗2年时乙肝病毒的YMDD变异情况

观察核苷类似物拉米夫定治疗慢性乙肝病人２年时ＹＭＤＤ变异情况及其与血清ＨＢＶＤＮＡ，ＡＬＴ水平等指标的关系。第一阶段（１－１２周）为随机、双盲、安慰剂对照研究，７２名ＨＢｓＡｇ．ＨＢｅＡｇ阳性至少６个月，ＨＢＶ－ＤＮＡ阳性的慢性乙肝患者分别口服拉米夫定１００ｍｇ／ｄ（ｎ＝５４）或安慰剂（ｎ＝１８）；第二阶段（１３－１０４周）所有患者均服用拉米夫定 １００ｇ／ｄ。５２周和 １０４周检查病毒的 ＹＭＤＤ变异．其总变异率分别为 １３．７％（８／５８）和 ３９．７％（２３／５８）。１０４周时变异组血清 ＨＢＶＤＮＡ，ＡＬＴ水平高于无变异组（３９４．９±７２７．９比 １６．３±５０．９，Ｐ＝０．００４８；６２．７±５７．９比２６ ４±２７．５，Ｐ＝０．００３），ＨＢＶＤＮＡ阴转率低于未变异组（１７．４％比４８．６％，Ｐ＜０．０５）；服用拉米夫定的慢性乙肝患者的ＹＭＤＤ发生率与服药时间长短有关，血清ＨＢＶＤＮＡ及ＡＬＴ水平与ＹＭＤＤ相关。     

拉米夫定联合中药复方胶囊治疗慢性乙型肝炎疗效及其对乙型肝炎病毒YMDD变异的影响

拉米夫定在慢性乙型肝炎抗病毒（HBV）治疗上的广泛应用，是近年来乙型肝炎治疗上的重大进展，已成为慢性乙型肝炎的基础用药，但每年约有20%的患者出现HBVP基因YMDD变异。而中药通过调整机体免疫功能来治疗慢性乙型肝炎在临床上有一定的疗效。本研究采用中西医结合的方法，通过观察拉米夫定联合中药复方胶囊治疗慢性乙型肝炎的疗效及对YMDD变异的影响。     

Relationship between hepatocellular carcinoma and hepatitis B virus genotype with spontaneous YMDD mutations

AIM: To investigate the relationship between hepatitis B virus (HBV) genotype with spontaneous YMDD mu-tations and hepatocellular carcinoma (HCC) in HBV-related cirrhosis. METHODS: We investigated 264 liver cirrhosis pa-tients who were not treated with antiviral drugs, in-cluding 81 patients with HCC. YMDD mutations were detected by fluorescent hybridization bioprobe poly-merase chain reaction (PCR) and melting curve assay using the Diagnosis Kit for HBV YMDD Mutation. Serum HBV genotypes were detected by real-time PCR using genotype-specific TaqMan probes. Statistical analysis was performed according to data type using the t test, χ2 test and unconditional logistic regression analysis. RESULTS: In the HCC group, genotype C strains, spon-taneous YMDD mutations, and genotype C strains with YMDD mutations were detected in 33 (40.74%), 13 (16.05%) and 11 (13.58%) patients, respectively. In the liver cirrhosis (LC) group, HBV genotype C strains,spontaneous YMDD mutations, and genotype C strains with YMDD mutations were detected in 33 (18.03%), 7 (3.83%) and 2 (1.09%) patients, respectively. The dif-ferences in genotype C strains, spontaneous YMDD mu-tations, and genotype C strains with YMDD mutations between the two groups were statistically significant (χ2=15.441, P=0.000; χ2=11.983, P=0.001; P=0.000). In the HCC and LC groups, there were seven patients infected by genotype B strains with YMDD mutations and 13 by genotype C strains with YMDD mutations. Further research revealed that HCC oc-curred in 2 patients infected by genotype B strains with YMDD mutations and 11 infected by genotype C strains with YMDD mutations. The difference was statistically significant (P=0.000). Unconditional logistic regres-sion analysis revealed that patients infected by geno-type C strains with spontaneous YMDD mutations had a 7.775-fold higher risk for the development of HBV-related HCC than patients infected by other type HBV strains (P=0.013, 95%CI: 1.540-39.264). CONCLUSION: Genotype C strains with spontaneous YMDD mutations ar     

拉米夫定治疗中乙型肝炎病毒YMDD野毒株和变异株的变化

目的 观察慢性乙型病毒性肝炎(CHB)患者应用拉米夫定治疗前后,YMDD野毒株及变异株的动态变化,并分析其临床意义。方法 取5例CHB患者治疗前与治疗48周的10份血清标本,先用PCR法扩增包括YMDD基序的乙型肝炎病毒(HBV)部分核苷酸序列,然后进行DNA序列测定,同时分别进行克隆,每份标本随机挑选20～24株单克隆,用实时荧光PCR法检测YMDD野毒株及其变异株。结果 5例CHB患者治疗前PCR产物直接测序结果未检出YMDD变异,治疗48周时有4例检出YMDD变异,但对每株克隆的分别检测显示：治疗前YMDD变异株(YIDD／YvDD)所占比率分别为0％、9．5％、0％、4．5％、5．6％;治疗48周时所占比率分别为100％、100％、65％、100％、0％。其中1例患者治疗前检出YIDD变异株,而治疗48周时YVDD变异株则变成优势株。治疗52周时,4例YMDD变异患者中2例HBVDNA和血清丙氨酸转氨酶(ALT)突破,1例患者ALT突破,但HBVDNA为阴性。结论 YMDD变异株在拉米夫定治疗前的血清中已存在,在服用拉米夫定后,由于选择性抑制了野毒株,使YMDD变异株由弱势株变成优势株,部分患者可导致拉米夫定临床耐药。YVDD变异株可能比YIDD变异株的复制能力强。     

Relationship between levels of DNA damage in lymphocytes and histopathological severity of chronic hepatitis C and various clinical forms of hepatitis B

BACKGROUND AND AIM: A significant proportion of cancer is attributable to DNA damage caused by chronic infection and inflammation. Because both hepatitis B and C viruses (HBV and HCV, respectively) cause chronic infection and inflammatory disease, the aim of the present study was to investigate whether there is a difference in peripheral DNA damage in patients with chronic HCV compared with patients with chronic HBV; and whether there is an association in the level of peripheral DNA damage with a natural history of HBV infection. METHODS: Twenty patients with chronic hepatitis C, 20 patients with chronic hepatitis B, 11 patients with cirrhosis secondary to hepatitis B, 12 inactive hepatitis B s antigen (HBsAg) carriers and 21 healthy subjects were included in the study. The DNA damage in lymphocytes was determined using the alkaline comet assay. RESULTS: Although the chronic hepatitis C group had similar levels of DNA damage compared with patients with cirrhosis due to hepatitis B (P > 0.05) and non-cirrhotic patients with chronic hepatitis B (P > 0.05), they had higher levels of DNA damage compared with inactive HBsAg carriers (P = 0.021) and controls (P = 0.001). Hepatitis B cirrhotic patients and patients with chronic hepatitis B had significantly higher levels of DNA damage than inactive HBsAg carriers (P = 0.002 and P = 0.012, respectively) and controls (both P = 0.001). Linear logistic regression analysis showed that chronic hepatitis C and HBV-related cirrhosis were discriminators in determining DNA damage in lymphocytes (beta 0.424 and P = 0.013, beta 0.393 and P = 0.016, respectively). CONCLUSIONS: Chronic hepatitis C, based on the severity of liver disease, or cirrhosis as an advanced form of HBV infection increase DNA damage in lymphocytes independently of confounding factors such as age, gender, body mass index and smoking habits.