拉米夫定治疗慢性乙肝的疗效及乙肝病毒YMDD变异的研究

目的评价拉米夫定治疗慢性乙肝病人的1年疗效、乙肝病毒YMDD变异率、变异与治疗前HBV-DNA、ALT水平的联系。方法治疗组按入选标准随机选择32例慢性乙型肝炎患者给予拉米夫定100 mg/d并随访1年,并于治疗开始后3、6、9、12个月检测肝功能、HBV-M、HBV-DNA、YMDD变异。对照组随机选择36例从未接受抗病毒治疗的HBV-DNA阳性、ALT异常的慢性乙型肝炎患者,检测YMDD变异株。结果①拉米夫定治疗一年,HBV-DNA转阴率71.88%(23/32),HBeAg/HBeAb血清转换率18.52%(5/27),ALT复常率62.5%(20/32);治疗前及治疗12个月后ALT水平分别为132.59±66.07、49.78±27.94,治疗前后差别有统计学意义(P<0.001)。②治疗组在治疗前未发现YMDD变异,治疗6个月发现2例YMDD变异,变异率6.25%,治疗12个月发现5例YMDD变异,变异率15.63%;对照组36例从未接受抗病毒治疗的慢性乙型肝炎病人中检测出2例YVDD变异株与野生株共存。③治疗前ALT<3×ULN组及≥3×ULN组YMDD变异率分别为11.76%、20.00%,两组差别无统计学意义(P=0.645);治疗前HBV-DNA<106copies/mL组及≥106copies/mL组YMDD变异率分别为5.88%、26.67%,两组差别无统计学意义(P=0.161)。结论拉米夫定能迅速抑制乙肝病毒复制、改善肝功能;治疗前HBV-DNA水平及ALT水平不足以预见YMDD变异的发生;乙肝病毒YMDD变异株存在于未使用拉米夫定的慢性乙肝患者中,建议在抗病毒治疗前对YMDD变异进行常规检测。     

Detection of YMDD motif mutants by oligonucleotide chips in lamivudine-untreated patients with chronic hepatitis B virus infection

Lamivudine, a nucleoside analogue, has been used widely as an effective antiviral agent for the treatment of patients with chronic hepatitis B virus (HBV) infection. However, the YMDD motif mutation of HBV polymerase resistant to lamivudine occurs very frequently after long term therapy. We developed an oligonucleotide chip for the detection of YMDD motif mutants resistant to lamivudine and investigated the prevalence of the mutants in patients with chronic HBV infection who had not been treated by lamivudine before. Forty patients who had not been treated with lamivudine were included in this study. Serum samples were tested by the oligonucleotide chips designed for detection of wild-type YMDD motif, M552V and M552I. Samples were confirmed by restriction fragment length polymorphism (RFLP) and direct sequencing. M552I mutants were detected by the oligonucleotide chips in 7.5% (3/40) of chronic HBV infected patients (2 chronic hepatitis and 1 cirrhosis). The results were in accordance with those of RFLP. YMDD motif mutants occur as natural genome variabilities in patients with chronic HBV infection who had not been treated with lamivudine before. Oligonucleotide chip technology is a reliable and useful diagnostic tool for the detection of mutants resistant to antiviral therapy in chronic HBV infection.     

Favorable efficacy of long-term lamivudine therapy in patients with chronic hepatitis B: an 8-year follow-up study

The long-term efficacy of lamivudine therapy in patients with hepatitis B virus (HBV) infection is still not clear. In this study, 20 non-cirrhotic Japanese patients infected with HBV received lamivudine therapy for more than 1 year and were followed for a median period of 8.5 years (range, 6.7-8.7 years). The rates of HBe antigen (HbeAg) negative, HBV-DNA undetectable, and alanine aminotransferase (ALT) normal level at the start of lamivudine were 55%, 25%, and 20% and 85%, 80%, and were 80%, respectively, at the last visit, including patients who received additional treatment. The values at the last visit tended to and were significantly higher than those at the start. The values improved at the last visit regardless of the emergence of YMDD motif mutant and continuation of lamivudine. YMDD mutant and biochemical relapse with mutant virus (breakthrough hepatitis) appeared in 65% and 45% during follow-up, respectively, but severe breakthrough hepatitis occurred in only 5%. Furthermore, 80% of patients who received additional treatment for breakthrough hepatitis, regardless of continuation of lamivudine, were ALT normal level at the last visit, in contrast to 25% untreated. HBsAg clearance occurred in two patients of the discontinuous lamivudine group with non-vertical transmission, who were relatively young. One was infected with HBV genotype C with breakthrough hepatitis and the other had no YMDD mutant and was infected with genotype D, a rare type in Japan. None developed cirrhosis or hepatocellular carcinoma (HCC) during follow-up. Our results suggest that long-term lamivudine therapy improves long-term prognosis, especially when additional treatment for breakthrough hepatitis is used.     

未经抗病毒治疗的慢性乙型肝炎病毒YMDD变异分析

目的探讨未经抗病毒治疗的慢性乙型肝炎患者中HBV多聚酶YMDD变异情况及与乙肝标志物之间的相关性。方法采用荧光定量PCR分析仪和ELISA方法分别对HBV-DNA含量、YMDD变异株及乙肝标志物进行检测。结果89例未经抗病毒治疗的慢性乙型肝炎患者YMDD变异率达13.5%,YMDD变异株以YIDD为主,占12.9%,YVDD占0.6%,并且其变异主要发生在HBeAg阳性患者中,HBeAg阳性占10.1%,抗-HBe阳性占3.4%。结论未经抗病毒治疗的乙肝患者仍存在较高的YMDD变异率,变异者中以YIDD变异株及集中在HBeAg阳性患者为主,临床上在应用抗病毒治疗前应对患者是否存在YMDD变异加以重视。     

未经拉米夫定治疗HBV YMDD变异的临床分析

目的分析未经拉米夫定治疗的HBV病毒YMDD变异出现的情况,探讨HBV病毒YMDD变异出现可能的机理,了解以YMDD自然变异的慢性HBV感染患者的肝损害情况。方法对140例HBVDNA阳性,未经拉米夫定治疗的慢性HBV感染者进行YMDD检测,同时检测谷丙转氨酶(ALT)、谷草转氨酶(AST)、血清总胆红素(TBIL)、白蛋白(ALB)、发病年龄、HBeAg与抗HBe等临床相关指标。结果140例未经拉米夫定治疗的慢性乙肝病毒感染者中20例自然发生YMDD变异,YMDD变异组与未变异组引起的肝损害无显著性差异(P>0.05)。YMDD变异与HBeAg与抗HBe的阳性表达无明显差异(P>0.05)。结论HBV病毒YMDD变异株作为一个准种与野毒株同时存在感染个体,YMDD变异对肝损害严重性无关,YMDD变异与HBeAg阳性率与抗HBe阳性率无明显差异。     

乙型肝炎病毒基因变异与转氨酶关系的探讨

目的：探讨乙型肝炎病毒基因变异与血清转氨酶水平的关系。方法：采用实时荧光PCR熔解曲线法检测948例乙型肝炎病毒感染者的YMDD变异，其中342例（YMDD变异株84例，YMDD野生株132例，YMDD阴性126例），同时检测其ALT、AST水平。结果：948例患者中检出YMDD变异株126例，其中单一变异株104例，混合变异株22例。342例中YMDD变异株、YMDD野生株和YMDD阴性的ALT、AST异常率分别为45．2％、53．0％、19．0％及42．9％、43．9％、17．5％。结论：乙型肝炎患者其乙肝病毒基因发生变异与其ALT、AST异常水平比较无统计学意义。     

Therapy of chronic hepatitis B: current challenges and opportunities

Better understanding of hepatitis B virus (HBV) replication, natural history and the immunopathogenesis of chronic hepatitis B, together with the introduction of effective agents with different mechanisms of action are the basis for better therapeutic strategies against chronic hepatitis B. Among currently available drugs, interferon-alpha and thymosin-alpha1 have only modest efficacy (approximately 40% vs 9-20% in controls). In the past decade, lamivudine has dominated in the treatment of chronic HBV infection because it is easy to use, safe, and is effective in terms of hepatitis B e antigen and/or HBV-DNA loss, ALT normalization, and improvement in histology. The response rate increases with increasing pretherapy alanine aminotransferase (ALT) levels, suggesting that patients with stronger endogenous immune response against HBV have a better response to direct antiviral agents. Lamivudine is also beneficial in decompensated cirrhotics with HBV replication. Hepatitic flares may occur after stopping lamivudine therapy in nonresponders and also in responders. Therefore, prolonged therapy is usually required. However, tyrosine-methionine-aspartate-aspartate (YMDD) mutations conferring resistance to lamivudine start to emerge after 6-9 months of therapy, and hepatitis flare, even decompensation, may develop after viral breakthrough. Thus the benefits of long-term lamivudine therapy must be balanced against the concern about YMDD mutations and the durability of treatment response. Adefovir dipivoxil, entecavir, emtricitabine, clevudine and other nucleoside/ nucleotide analogues have shown encouraging results and some agents appear effective in patients with YMDD mutants. Further development of new drugs and new strategies may help to improve treatment in the new century.     

乙型肝炎病毒前C基因区变异对YMDD变异毒株复制活性的影响

目的调查接受拉米夫定治疗的乙型肝炎病毒（HBV）感染者中HBV前C基因区终止密码变异（A1896，PC）和基本核心启动子变异（BCP，T1762／A1764）对YMDD变异毒株复制活性的影响。方法应用聚合酶链反应-限制性片断长度多态性（PCR—RFLP）法对197例接受拉米夫定治疗后发生YMDD耐药变异的患者进行HBV基因型、PC及BCP变异检测，并用实时荧光定量法对所有患者血清HBVDNA进行定量。结果197例YMDD变异株感染者中B基因型占51．8％，C基因型占48．2％；有61例（31．0％）发生PC变异，69例（35．0％）发生BCP变异；PC变异在B基因型中的发生率明显高于C基因型（X^2=8．433，P=0．004），而BCP变异在C基因型中的发生率显著高于B基因型（X^2=16．83，P〈O．001）；发生PC或BCP变异的HBV感染者，其血清中HBVDNA水平与野生株相比差异均无统计学意义。结论HBV前C基因区的PC或BCP变异与基因型具有相关性，但这两种变异对YMDD变异株感染者的血清病毒水平均无影响。