慢性乙型肝炎与肝硬化患者乙型肝炎病毒S蛋白变异分析

目的探讨慢性乙型肝炎(CHB)患者、肝硬化患者乙型肝炎病毒(HBV)S蛋白变异的差异及其临床意义。方法选取CHB患者114例,其中慢性HBV携带者41例(慢性HBV携带组)、非活动性乙型肝炎表面抗原(HBsAg)携带者38例(非活动性HBsAg携带组)、肝硬化组35例(肝硬化组)。采用测序法检测所有对象的HBV S蛋白基因序列。结果慢性HBV携带组、非活动性HBsAg携带组与肝硬化组之间年龄和HBV DNA载量差异均有统计学意义(P<0.01),性别及HBV基因型差异均无统计学意义(P>0.05)。肝硬化组HBV S蛋白总体变异率明显高于非活动性HBsAg携带组和慢性HBV携带组(P<0.05、P<0.01)。慢性HBV携带组、非活动性HBsAg携带组与肝硬化组S蛋白的主要亲水区(MHR)外变异率及细胞毒T淋巴细胞(CTL)+辅助性T淋巴细胞(Th)免疫表位区变异率依次升高(P<0.01)。3组之间S蛋白的MHR及位于MHR内的"a"决定簇、LOOP1和LOOP2的变异率差异均无统计学意义(P>0.05),MHR外的非免疫表位区变异率差异亦无统计学意义(P>0.05)。慢性HBV携带组中有1例患者同时出现MHR外Th免疫表位区、CTL免疫表位区和非免疫表位区3个位点变异,1例患者出现MHR与MHR外Th免疫表位区2个位点变异,其他患者均为单点变异,且MHR外CTL+Th免疫表位区与非免疫表位区变异率相当,呈随机分布。非活动性HBsAg携带组有5例(13.15%)患者出现2个位点以上的变异,肝硬化组有9例(25.71%)患者出现2个位点以上的变异,且2个组的变异位点集中于MHR外CTL+Th免疫表位区。结论HBV S蛋白MHR外,尤其是MHR外CTL+Th免疫表位区变异不仅与HBeAg阴性血清学状态相关,也与肝硬化相关。

Analysis of hepatitis B virus S protein mutation in chronic hepatitis B and cirrhosis patients

Objective To investigate the difference of hepatitis B virus(HBV)S protein mutations in patients with chronic hepatitis B(CHB)and cirrhosis,and to assess its role in clinical application.Methods A total of 114 patients with CHB were enrolled,and they were classified into 3 groups,asymptomatic HBV carriers(41 cases),inactive hepatitis B surface antigen(HBsAg)carriers(38 cases)and cirrhosis patients(35 cases).DNA sequencing was used to determine HBV S protein gene mutation.Results There was statistical significance in age and HBV DNA loads of asymptomatic HBV carrier,inactive HBsAg carrier and cirrhosis groups(P<0.01),and there was no statistical significance in sex and HBV genotypes(P>0.05).The gene mutation frequency of HBV S protein was higher in cirrhosis group than those in asymptomatic HBV carrier group(P<0.05)and inactive HBsAg carrier group(P<0.01).The mutation rates in outside major hydrophilic region(MHR)and cytotoxic T lymphocytes(CTL)+helper T cell(Th)epitopes were increased in the 3 groups(asymptomatic HBV carrier0.05).Single amino acid substitution was found in the majority of asymptomatic HBV carriers except 2 patients.Of these,one had 3 amino acid substitutions in CTL+Th epitopes and non-immune epitopes located outside MHR,and another had 2 amino acid substitutions in MHR and CTL+Th epitopes outside MHR.The mutation rates in CTL+Th epitopes and non-immune epitopes outside MHR were comparable and random for asymptomatic HBV carriers,whereas more than 2 mutation sites were determined in 5 cases of inactive HBsAg carriers(13.15%)and 9 patients with cirrhosis(25.71%).These mutation sites preferentially concentrated at the CTL+Th epitopes outside MHR.Conclusions High prevalence of outside MHR variants especially CTL+Th epitopes is associated not only with hepatitis B e antigen(HBeAg)-negative serostatus but also with severe liver diseases,particularly cirrhosis.