生物信息学解读丙型肝炎病毒结构与免疫病理学改变的关联性

Bioinformatics-based explanation of relationship between structure of hepatitis C virus and its immuno-pathological characteristics

目的:分析丙型肝炎病毒(HCV)基因组编码序列结构特征及蛋白同源性,预测HCV非结构蛋白(NS)3序列的抗原表位。方法:以Envision免疫组织化学两步法检测肝移植受体肝组织内HCV抗原。从美国国立生物技术信息中心(NCBI)数据库中获取HCV编码序列,利用RPS-BLAST蛋白同源性比对软件进行序列分析;ProPred-Ⅰ软件预测NS3编码区段的T细胞抗原表位。结果:37%的受检病例肝细胞核对Tordji-22单克隆抗体起反应,33.3%的受检病例肝细胞核或细胞质对NS3抗体起反应。HCV编码产物HCV糖蛋白(gp)1的NS3区为保守区,与多种人类解旋酶具有同源性;其余各编码区未检测到与人类同源性。NS3区显示有CD4+和CD8+T细胞表位。结论:HCV NS3区含有与人类解旋酶同源的保守序列。解旋酶在细胞核参与核酸复制与DNA修复,故针对HCV NS3的抗原检测有可能与人类解旋酶起交叉反应。NS3的抗原表位特征可能是机体抗病毒同时破坏自身肝脏结构的分子基础。

Objective To analyze the encoding sequence characteristics of hepatitis C virus （HCV） genome and its protein homology, and predict the antigenic epitope of non-structural protein （NS）3 region. Methods HCV antigen was detected by Envision two-step immunohistochemistry staining in 27 liver transplant recipients. Homologous analysis was performed via reversed position specific blast （RPS-BLAST） software, following HCV encoding sequence extraction from National Center for Biotechnology Information （NCBI） database. Simultaneously, the antigenic epitope of NS3 sequence was predicted by ProPred-Ⅰ software. Results Nuclear staining rate was 37% by Tordji-22 antibody and 33.3% by NS3 antibody, respectively. HCV genome with 9 646 bp encodes HCV glycoprotein （gp） 1, which encompass structural proteins and NS. There was a conserved domain in NS3 sequence, which was homologous to that of human helicase. No homology was identified in other HCV encoding sequences. The CD4 and CD8 positive T cell epitopes were predicted in HCV NS3 sequence. Conclusions HCV NS3 protein is homologous to human helicases, which are involved in DNA replication and repairing. Cross-reaction with human helicases might occur in the detection of NS3 antigen. The potential mechanism of liver injury in chronic hepatitis C might be related with the cross-reaction characteristics of antigenic epitope characteristic of NS3.