拉米夫定治疗慢性乙型肝炎出现YMDD变异患者的临床意义

目的探讨拉米夫定治疗慢性乙型肝炎患者YMDD变异株YVDD和/或YIDD的变异情况。方法用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)分析方法,检测65例慢性乙型肝炎患者血清YMDD变异情况。结果65例血清标本中,检出YMDD变异31例,其中YVDD变异22例(33.8%),YIDD变异8例(12.3%),YVDD与YIDD混合变异1例(1.5%)。31例发生变异者中服用拉米夫定满一年发生YVDD变异4例,YIDD变异2例;服用拉米夫定满二年发生YVDD变异8例,YIDD变异3例,YVDD与YIDD变异1例;服用拉米夫定满三年发生YVDD变异10例,YIDD变异3例。结论YMDD变异与病情变化无关,随着拉米夫定治疗时间延长,发生变异的机会增大。     

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。     

YMDD自然变异毒株流行病学调查

目的 了解YMDD自然变异的发生情况及影响YMDD自然变异的因素.方法 依托国家食品药品监督管理局注册药物临床试验"阿德福韦酯片治疗成人慢性乙型肝炎的多中心、随机、双盲、对照临床研究(Ⅲ期)"开展.采用乙型肝炎病毒(HBV)拉米夫定耐药荧光PCR检测试剂盒及实时荧光PCR基因型分型试剂盒,对该临床研究筛选期183例半年内未经抗病毒治疗的慢性乙型肝炎(CHB)患者血清标本进行检测,并通过Logistic逐步回归对影响YMDD自然变异检出率的可能因素进行多因素分析.结果 183例CHB患者中,检出YMDD自然变异毒株者40例(21.86%),其中YVDD阳性36例,YIDD阳性3例,YVDD和YIDD同时阳性者1例;变异毒株占总病毒量50%以上者6例,占25%～50%者9例,占9%～25%者25例.B基因型CHB患者中YMDD自然变异检测阳性的比例高于C基因型(31.67%对17.65%,P=0.038 2),患者性别、年龄、HBeAg状态、血清HBV DNA载量及丙氨酸氨基转移酶(ALT)水平对YMDD自然变异检出率无显著影响(P＞0.05).结论 在CHB患者中存在YMDD自然变异毒株;YMDD自然变异的发生率与患者性别、年龄、HBeAg状态、HBV DNA水平、ALT水平无关.B基因型较C基因型更易出现YMDD自然变异.     

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．     

慢性乙型肝炎患者血清中病毒的YMDD自然变异

近年来,随着拉米夫定的广泛应用,部分患者出现YMDD变异而产生耐药性,最常见的有YVDD(M552V)和YIDD(M552I)变异.因此,服用拉米夫定后患者的YMDD变异成为近几年的研究热点[1-2];但有研究证实存在YMDD自然变异[3].国内目前尚缺乏大样本YMDD自然变异率的研究,我们对未经治疗的449例慢性乙型肝炎患者进行YMDD变异株的检测,探讨了不同慢性乙型肝炎患者血清中HBV YMDD的自然变异率及其与血清HBV DNA水平的关系.     

慢性乙型肝炎患者拉米夫定治疗24周时YMDD变异对疗效的影响

目的 使用基因芯片方法检测乙型肝炎病毒(HBV)YMDD变异的发生情况,研究YMDD变异发生与肝功能损伤和HBV复制水平指标之间的关系。方法 120例以常规剂量(100mg/d)口服拉米夫定的慢性乙型肝炎患者,治疗前和治疗第24周抽取血清检测丙氨酸氨基转移酶(ALT)、HBV DNA(定量)水平,对24周HBV DNA阳性的17例患者血清样本,以基因芯片方法检测其治疗前和治疗24周时血清中YMDD变异是否存在,并分析该变异发生和ALT、HBV DNA的关系。结果 (1)120例入选患者治疗24周时有17例患者HBV DNA仍为阳性,除外治疗前已存在的1例感染变异病毒,基因芯片共检出7例变异,变异率为5.8％。其中纯变异2例,YIDD变异1例,YVDD变异1例,混合变异5例,其中YMDD/YVDD变异3例,YVDD/YMDD变异2例。(2)变异组在治疗前和治疗24周时ALT定量水平与非变异组相比,差异无显著性,P>0.05。(3)变异组在治疗前和治疗24周时HBV DNA定量水平与非变异组相比,差异无显著性,P>0.05。结论 在拉米夫定治疗过程中,YMDD基因变异发生对肝脏炎症活动度和病毒复制的抑制作用无显著影响。     

氧化苦参碱联合胸腺肽治疗拉米夫定所致YMDD变异后的慢性乙型肝炎疗效观察

本文观察氧化苦参碱联合胸腺肽治疗拉米夫定所致的HBV YMDD变异慢性乙型病毒性肝炎患者的临床疗效。入选64例慢性乙型病毒性肝炎患者,其中男48例,女16例,平均年龄36.4岁,自1999年1月至2001年12月经拉米夫定抗病毒治疗36周～104周后,已出现病情反复,HBeAg,HBV DNA重新转阳,肝功能异常,用PCR检测肯定YMDD区已发生YIDD或YVDD等变异。随机将该64例分为二组:     

乙型肝炎病毒P基因变异的检测及其意义

目的采用错配PCR扩增方法进行乙型肝炎病毒(HBV)P基因YMDD变异的检测,并对其临床意义进行初步研究.方法应用分子克隆方法,构建YMDD、YVDD、YIDD变异的阳性质粒,并进行敏感性及特异性试验.对44例经拉米夫定治疗1年、HBVDNA持续阳性的乙型肝炎患者检测YMDD变异情况.结果经PCR方法、酶切鉴定及直接测序鉴定出YMDD、YVDD和YIDD质粒构建成功,且该方法具有较好的敏感性和特异性.44例拉米夫定治疗1年、HBVDNA持续阳性的乙型肝炎患者存在YMDD变异,半年出现变异5例,变异率为11.36%;1年出现变异7例,变异率为15.91%.结论本检测方法简便、实用,抗病毒药物压力是导致HBVYMDD变异的重要因素.     

基因芯片和聚合酶链反应-限制性片段长度多态性法检测拉米夫定耐药的慢性乙型肝炎患者YMDD变异

目的对基因芯片和聚合酶链反应-限制性片段长度多态性(PCR-RFLP)两种方法检测YMDD变异进行比较。方法取40例临床考虑拉米夫定耐药的患者血清，分别用基因芯片和PCR-RFLP法检测YMDD基序变异情况。随机抽取8份血清标本进行测序验证两种方法的准确性。结果40例患者血清标本中，用基因芯片法检测出YMDD变异阳性标本27例，其中，YIDD变异4例，YVDD变异16例，YVDD／YMDD共存12例；YIDD与YVDD混合变异7例。用PCR-RFLP法检测出变异阳性标本21例。在变异株中，YIDD变异和YVDD变异各9例，YIDD／YVDD混合变异3例，明显低于基因芯片的检出率。结论1、用基因芯片能快速灵敏地检测YMDD变异情况，并能检测到患者体内变异株与野生株混合存在形式；2、基因芯片能同时检测两种YMDD变异株和YMDD野生株，优于PCR-RFLP法，适用于临床检测乙型肝炎病毒YMDD变异。     

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.     

The hepatitis B virus

Of all the hepatotropic viruses, HBV is associated with the greatest worldwide morbidity and mortality. This is because of the ease of transmission and the potential for progression to a chronic infective carrier state, with the complications of cirrhosis and hepatocellular carcinoma. The use of PCR has shown that some of the earlier concepts concerning the interpretation of serological data were inaccurate. Many patients with anti-HBe and anti-HBs have viral DNA detectable by PCR, and some hepatocellular carcinoma patients have detectable HBV DNA in their livers in the absence of all serological markers of HBV disease. The clearance of HBV infected cells from the liver is dependent on the interplay between the interferon system and the cellular limb of the host immune response. The importance of the nucleocapsid proteins as targets for sensitized cytotoxic T cells has been established for chronic HBV infection. The importance of pre-S sequences as inducers and targets of the virus-neutralizing humoral immune response is becoming established, but their precise role must await the development of in vitro models of hepadnavirus infection and a greater understanding of the mechanisms of viral uptake. The epidemiology and clinical course of the disease can be modified by immunization, immune stimulation and antiviral chemotherapy. For the developing world, a programme of immunization at birth would be the most effective way of eliminating this disease, but at present the cost is prohibitive. For the developed world, immunization is realistic for the at-risk population, and anti-viral and immunostimulatory therapy available for those already infected. In adult acquired chronic HBV infection alpha-interferon produces HBe antigen clearance in 40-60% of cases and is followed by resolution of the hepatic inflammation. Results in neonatally acquired infection are less impressive and prednisolone priming followed by interferon may be needed. The presence of a mutation in the pre-core region of some virus isolates has recently been described. Hepatocytes infected with this virus cannot produce HBe antigen and the course of the liver disease is fairly rapid. Whether this mutant causes liver damage in the same way as the wild virus or is directly cytopathic remains unclear, and its relationship to fulminant hepatitis is under investigation.     

Hepatitis B virus taxonomy and hepatitis B virus genotypes

Hepatitis B virus (HBV) is a member of the hepadnavirus family. Hepadnaviruses can be found in both mammals (orthohepadnaviruses) and birds (avihepadnaviruses).The genetic variability of HBV is very high. There are eight genotypes of HBV and three clades of HBV isolates from apes that appear to be additional genotypes of HBV. Most genotypes are now divided into subgenotypes with distinct virological and epidemiological properties. In addition, recombination among HBV genotypes increases the variability of HBV. This review summarises current knowledge of the epidemiology of genetic variability in hepadnaviruses and, due to rapid progress in the field,updates several recent reviews on HBV genotypes and subgenotypes.     

Persistence of hepatitis B virus DNA after serological clearance of hepatitis B virus

Using Southern blot technique, the state of hepatitis B virus (HBV) DNA in liver tissue was investigated in 16 patients who were sero-negative for hepatitis B surface antigen (HBsAg) but positive for its antibody (anti-HBs). In only one case, was HBV DNA found in liver tissue in a heterogeneously integrated form. In this case, digestion with Taq I demonstrated integrated HBV DNA as two definite bands at 1.8 and 0.5 kbp. This suggests that HBV DNA in some cases persists even after HBV infection has been cleared serologically. It is possible that this persistence of HBV DNA plays an important role in hepatocarcinogenesis.     

Dual chronic hepatitis B virus and hepatitis C virus infection

Dual hepatitis B virus (HBV) and hepatitis C virus (HCV) infection are common in HBV or HCV endemic areas. However, several clinical and pathogenetic issues remain unresolved. First, clinical and in vitro studies suggest the interactions between two viruses. The dynamics of the interaction in untreated setting versus treated setting and its influence on the long-term outcomes await further studies. A key issue regarding viral interactions is whether modulation of infection occurs in the same dually infected individual hepatocyte of the liver. Clarifying this issue may help to understand the reciprocal interference between HCV and HBV and provide clues for future immunopathogenetic studies. Second, the prevalence and clinical significance of coexisting occult HBV infection in patients with chronic HCV infection need further investigations. Third, combination therapy of peginterferon alfa-2a and ribavirin appears to be just as effective and safe for the treatment of hepatitis B surface antigen (HBsAg)-positive patients chronically infected with active chronic hepatitis C as it is in patients with HCV monoinfection. Nevertheless, one-third of dually infected patients with nondetectable serum HBV DNA-level pretreatment developed HBV reactivation posttreatment. How to prevent and treat this reactivation should be clarified. Furthermore, about 10% of the dually infected patients lost HBsAg. Underlying mechanisms await further investigations. Finally, the optimal treatment strategies for dually infected patients with hepatitis B e antigen-positive chronic hepatitis B should be identified in future clinical trials.     

Serum hepatitis B virus DNA in acute hepatitis type B

Sera obtained within 7 days after clinical onset of acute hepatitis type B were positive for hepatitis B virus (HBV) DNA by spot hybridization only in 4 out of 45 patients who subsequently recovered, but in 10 out of 10 patients who instead developed chronic infection. These results indicate that in uncomplicated acute hepatitis B, virus replication is limited to an early phase of infection, often preceding the onset of clinical symptoms, and suggest that serum HBV-DNA may represent an early and predictive marker of chronicity.     

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.     

乙型肝炎病毒的传播

乙型病毒性肝炎(hepatitisbvirus,HBV),简称乙肝,在甲、乙、丙、丁、戊型肝炎中最为严重的一种.他一直是我国“八五”、“九五”、“十五”重点医疗科研攻关项目.众所周知,乙肝危害已成为一种严重的世界性疾病,全球大约有20多亿人感染过HBV,其中约有4亿人为慢性感染.WHO已将HBV感染列为世界第九死亡原因,每年全世界死亡人数约30万.我国是HBV感染高发区,有50-70%的人感染过HBV,约有1.7亿人(占全国人口的十分之一还要多)是HBsAg携带者.我国现患乙肝者约3000万,其中60%以上为慢性乙肝患者.可见乙肝患病者之多,对人类危害之大.为了让人们了解乙肝,本文从HBV的感染,发病、转归(慢性乙肝,肝硬化、肝癌)和药物治疗进行系统的介绍和讨论.     

Myocarditis and hepatitis B virus

Two patients with hepatitis B virus infection and myocarditis are reported. The implicated pathogenesis was an immune complex mechanism in one patient. Both patients presented with heart failure and arrhythmia which were controlled with conventional medical therapy. Echocardiography played an important role for early detection of left ventricular dysfunction. The efficacy and safety of corticosteroid therapy is still conjectural. Acute hepatitis B infection should be a differential diagnostic consideration in the etiology of acute myocarditis.     

Occult hepatitis B virus infection

Occult hepatitis B virus(HBV)infection(OBI)refers to the presence of HBV DNA in the absence of detectable hepatitis B surface antigen.Since OBI was first described in the late 1970s,there has been increasing interest in this topic.The prevalence of OBI varies according to the different endemicity of HBV infection,cohort characteristics,and sensitivity and specificity of the methods used for detection.Although the exact mechanism of OBI has not been proved,intrahepatic persistence of viral covalently closed circular DNA under the host’s strong immune suppression of HBV replication and gene expression seems to be a cause.OBI has important clinical significance in several conditions.First,OBI can be transmitted through transfusion,organ transplantation including orthotopic liver transplantation,or hemodialysis.Donor screening before blood transfusion,prophylaxis for high-risk organ transplantation recipients,and dialysis-specific infection-control programs should be considered to reduce the risk of transmission.Second,OBI may reactivate and cause acute hepatitis in immunocompromised patients or those receiving chemotherapy.Close HBV DNA monitoring and timely antiviral treatment canprevent HBV reactivation and consequent clinical deterioration.Third,OBI may contribute to the progression of hepatic fibrosis in patients with chronic liver disease including hepatitis C.Finally,OBI seems to be a risk factor for hepatocellular carcinoma by its direct protooncogenic effect and by indirectly causing persistent hepatic inflammation and fibrosis.However,this needs further investigation.We review published reports in the literature to gain an overview of the status of OBI and emphasize the clinical importance of OBI.     

Occult hepatitis B virus infection

Many studies have shown that hepatitis B virus infection may also occur in hepatitis B surface antigen-negative patients. This occult infection has been identified both in patients with cryptogenic liver disease and in patients with hepatitis C virus-related chronic hepatitis, and much evidence suggests that it may be a risk factor of hepatocellular carcinoma development. However, several aspects of this occult infection remain unclear, such as its prevalence and the factor(s) involved in the lack of circulating hepatitis B surface antigen. Moreover, it is uncertain whether the occult hepatitis B virus infection may contribute to chronic liver damage, considering that it is usually associated with a suppressed viral replication. Evidence and hypotheses concerning this fascinating field of biomedical research are reviewed.