Research On The Immunogenicity Of Synthetic Peptides Of HCV HVR1 And Th1/Th2 Immune Response Of Hepatitis C

About 1.7 billion people are infected with HCV in the world ,and among them above 50% will become chronic. What's more , 20% of HCV patients will develop cirrhosis and perhaps hepatocellular carcinoma 20-30 years later . In most organ transplant centers , HCV infection has become the major cause of liver transplant. But its nosogenesis is still not clear. So HCV infection is now a world-wide health problem. The 27-aa hypervariable region 1 (HVRl)in the N-terminal part of the putative envelope protein of HCV encoded by the E2 gene shows a high degree of variation and heterogeneity and appears to contain major neutralizing epitopes.This region can induce both strain specific or non-specific antibodies (cross-reactive antibodies) in experimental animals, study on HVR1 is one of the hottest points in HCV research.Among the synthetic peptides which we designed before, No.l peptide perform well in various biological tests. In this research, we compare its aa sequence with the aa sequence of the Il/lb and III/2a strain, both of which are the prevalent strain in Chinese population. Also , we compare it with the HVR1 sequences of genebank. Then,we digitally analyze its conformation and antigencity. Results show that its aa sequence is similar with aa with the highest frequency, and theaa mutation usually takes place between aa of similar character, which mean aa at the N terminal of HVR1 has somewhat conservativeness. We aslo test antibody responses against No.1 peptide in 208 HCV dynamic sera. Results show that (l)totally 79.8% of these sera turn to be positive in the reaction with No.l peptide. (2)the sera reactabilty against No.1 peptide in liver cirrhosis HCV patients group is higher than that of chronic HCV patients group; the sera reactabilty against No.l peptide in active liver cirrhosis liver patients group is higher than that of mild or moderate chronic HCV patients groups . There exists relation between the sera reactabilty against 7aa mimic epitope and different stages of diseases course. In its reaction with long-term sera from 11 patients, we can found that though with some up and down, its reactivity with sera keeps positive in fairly long time. Our method in designing peptide helps to overcome the lose of immune supervision caused by aa mutation in HVR1.We detected the cytokine secretion of the PBMC of HCV patients in vitro with or without peptide stimulation, hoping to make preliminary exploration of the nature of the immune response and its relation with pathogenesis of HCV. Without peptide stimulation, we found the rise of the secretion of IL-10, TNF-a and IFN- in the culture of PBMC of HCV patients, especially IL-10 which means Th2 tendency in the immune responses in HCV patients. Th2 tendency may helps chronicity of HCV infection. After peptide stimulation, wefound obvious rise of the secretion of IL-10, TNF- a and IFN- compared with the controls without peptide stimulation, and especially IFN- Y which means it has induced some Thl immune responses.This Research forms a firm foundation for the further research on the HCV peptide and DNA vaccine. And it also provides a novel way for the clinical treatment of HCV infection.