Screen Genotype-specific Epitope Polypeptides Based On Conserved Sequence Assessment In HCV E2Region And B-cell Epitope Prediction

Backgrounds:Hepatitis C is an infectious disease with world-wide distribution caused by HCVinfection. HCV chronic infection in patients can lead to liver fibrosis and cirrhosis, evenhepatocellular carcinoma. The high mutation rates of HCV genome, especially of E2region, make HCV genotypes more diversified, detection of HCV and genotypes needto be more rigorous, suboptimal response to conventional antiviral treatment in patientsoccur more often and vaccine development aiming to prevent HCV infection moredifficult. Epitope polypeptides, generated based on conserved sequence assessment andcell epitope prediction, become hot topic of scientific research nowadays, because of itshigh conservation and strong antigenicity. Exploration and research of HCV conservedepitope polypeptides in the detection, treatment and prevention of HCV infection hadalready been applied widely.Objectives:Based on conserved sequence assessment in HCV E2region and B-cell epitopeprediction, we analyzed differences between HCV infected patients and controls,screened genotype-specific responses. Based on the above, we hoped to establish HCVgenotype serological ELISA detection technology; specific antibodies, which couldidentify these epitope polypeptides, block receptors where HCV infected humantargeting cells or inactivated virus through antigen-antibody complexes, thus achieveantiviral roles in HCV infection; epitope polypeptides became antigen candidate ofprevention HCV infection and provided the basis for new peptide vaccine development.Methods:We predicted3genotype-specific and concomitant conserved B-cell epitopesequences and synthesized epitope polypeptides chemically, through conservationassessment of40sequences in genotype1a,1b and4d HCV E2region by using MEGAv5.05software and B-cell epitope prediction. Through ELISA examination, OD450values were assayed, when epitope polypeptides were mixed with sera from29HCVinfection and25none HCV infection people. Differences were analyzed by SPSS v20.0 software. Student’s t test was used for comparisons between two groups, i.e. HCVinfection group and control group.Results:4B-cell epitope polypeptides were synthetized in this study, including genotype1aspecific sequence DC-13(434-DTGWLAGLFYYHK-446), genotype1b specificsequence HC-13(434-HTGFLAALFYAKS-446), genotype4d specific sequence NC-13(434-NTGFLASLFYTHK-446) and concomitant sequence FC-9(447-FNSSGCPER-455), respectively. ELISA examination and data analysis showed:DC-13, NC-13and HC-13responses were higher in HCV infection group than that incontrol group and the differences were statistically significant; HC-13responses washigher in HCV genotype1b infection group than that in HCV genotype2a infectiongroup and the difference was statistically significant. In contrast, the differences ofHC-13responses between with HCV genotype1b group and control group, were notstatistically significant.Conclusion:4HCV B-cell epitope polypeptides were synthetized, including genotype1a,1b,4d specific and concomitant epitope polypeptides. Among these, sera responses ofgenotype1a,4d specific and concomitant epitope polypeptides in HCV infectionpatients were higher than none-HCV infection people, and genotype1b specific epitopepolypeptides in HCV1b infection patients was higher than HCV2a infection patients.