丙型肝炎病毒包膜基因变异与急性丙型肝炎疾病转归的动态研究  

Dynamic study of the rdationship of genetic evolution for hepatitis C virus envelope glycoproteins with the outcome of acute hepatitis C

作　　者：陈嵩[1] 陈佳[1] 王宇明[1] 

机构地区：[1]第三军医大学西南医院全军感染病研究所,重庆400038

出　　处：《中华微生物学和免疫学杂志》2007年第2期123-128,共6页Chinese Journal of Microbiology and Immunology

基　　金：国家自然科学基金资助课题（3970694）

摘　　要：目的 探讨HCV包膜基因变异与急性丙型肝炎疾病转归的关系。方法 前瞻性收集到5例HCV急性感染者的系列血清标本，其中2例一过性感染，3例持续性感染。采用高精确度DNA聚合酶，较长PCR扩增HCV基因组结构区（包括C区C端、E1和E2区N端）1kb产物并进行克隆，每份标本挑选33个克隆，以异源双链和单链构象多态分析筛查的代表性克隆型DNA进行测序，并对HCV的E1、HVR1及HVR1除外的E2区核酸序列的非同义碱基替换率、同义碱基替换率以及氨基酸序列的理化特征进行分析。结果 HCV持续性感染者急性期与慢性期的标本比较，HVR1基因差异性明显大于E1（0．0322±0．0068 vs-0．0020±0．0014，P〈0．05）和HVR1以外的E2区（0．0322±0．0068VS0．0017±0．0011，P〈0．05），而一过性感染者感染初期与病毒清除前标本比较，HVR1、E1和HVRl以外E2基因差异性则无明显改变。＂HCV持续性感染者的E1（0．23×10^-3±0．15×10^-3）、HVR1（2．76×10^-3±1．51×10^-3）和HVR1以外E2区（0．50×10^-3±0．10×10^-3）的非同义碱基替换率比较，HVR1非同义碱基替换率呈明显增高趋势。相反，一过性感染者E1、HVR1和HVR1以外E2区的同义碱基替换率和非同义碱基替换率则无明显改变。E1、E2区所有半胱氨酸及潜在的糖基化天冬酰胺均高度保守，HVR1第11、25、27位置保持碱性氨基酸。结论 HCV持续感染与宿主免疫反应对HVR1的阳性选择相关，HVR1区特异位置保守的碱性氨基酸可供研制HCV疫苗时参考。Objective To investigate the relationship of genetic evolution of hepatitis C virus envelope glycoproteins with the outcome of acute hepatitis C. Methods HCV quasispecies were characterized in specimens collected every two to six months from a cohort of acutely HCV-infected subjects. We evaluated two individuals with spontane- ously cleared viremia and three individuals with persistent viremia by 33 clones 1kb amplicons that spanned E1 and the 5＇ half of E2, including hypervariable region 1 （ HVR1 ）. To detect representative variants for sequencing, thirty-three cloned eDNAs were assessed by combined analysis of a single-stranded conformational polymorphism （SSCP） method and heteroduplex analysis （HDA）. For each patient, the rates of both synonymous and nonsynonymous substitutiom for the El, HVR1 and E2 regions outside HVR1 were evaluated. Amino acid sequences were analyzed for the physieochemical characterstics. Results The genetic diversity （genetic distance） within HVR1 was consistently higher than that in the complete E1 （0.0322±0.0068 vs -0.0020±0.0014, P 〈0.05） and E2 regions outside HVR1 （0.0322 ±0.0068 vs 0.0017 ±0.0011, P 〈0.05） in individuals with persistent viremia, but did not markedly change over time in those with clearance of viremia. For individuals with persistent viremia, the rate of nonsynonymous substitutions within the HVR1 region （2.76×10^-3±1.51±10^-3 ） predominated and gradually increased, compared to that in the E1 and E2 regions outside HVR1 （0.23×10^-3±0.15×10^-3, 0.50×10^-3 ±0.10×10^-3）. By contrast, the rotes both nomynonymous and synonymous substitutions for the E1 and E2 regions including HVR1 were consistently lower in individuals with clearance of viremia. All eysteine residues and N-hnked glycosylation sites were 100% conserved among the sequenced cloned cDNAs from each individual. Despite the high degree of variability within HVR1, basic residues were globally observed at positions 11, 25 and 27. Conclusion HCV persistence is a

关 键 词：丙型肝炎病毒 包膜基因 准种 演化动态 

分 类 号：R686[医药卫生—骨科学]