Study On DNA Immunization Of Mice With Plasmid Encoding Mimic Epitopes Of The Hypervariable Region 1 Of Hepatitis C Virus

Hepatitis C virus (HCV) is the major cause of non-A non-B viral hepatitis .More than one billion people infected with HCV will develop chronic hepatitis,and some will progress to cirrhosis and perhaps hepatocellular carcinoma . But its nosogenesis is still not clear. So HCV infection is now a worldwide health problem. Many research have shown that the hypervariable region 1 (HVR1) of HCV contains a principal neutralization epitope,and can induce cross-reactive anti-HVR1 antibodies against different HCV subspecies, and suppose that the conservative epitopes in this region is the molecular basis for cross-reaction.Seven HVR1 mimic peptides were designed and synthesized based on the analysis of sequence diversity of HCV HVR1 in Chinese patients infected with genotype II/1b and III/2a and antigen properties of these peptides. DNA immunization, which allows the de novo synthesis of antigen in host's cells, is able to elicit protective humoral and cellular immune responses in animal models. In this research, recombinant plasmid (pCDN A3.1-target gene ) encoding 4 chosen mimic peptides of HCV HVRl(No.l, No.5, No.6, No.7)was constructed and used to immuniz e Balb/c mice by intramuscular injection .7 weeks after immunization, immunized mice produced high titers of antibodies against these mimic epitopes. They are 1:800, 1:200, 1:200, l:400(aganst No.1, No.5, No.6, No.7) respectively. The results are higher than those of peptides immunization.We use synthetic peptides to stimulate the spleen cells of immunizedmice in vitro. The obvious cell proliferations were observed after stimulation. The stimulation index(SI) of No.l, No.5, No.6,No.7 are 71.45 3.1,12.64 2.5,10.05 1.9,31.20 2.4 respectively. In our research, cytokines secretion of spleen cells of mice after stimulation of HVR1 antigen synthetic peptides was also tested. There is a rise of IFN-y, TNF-a, IL-4, IL-10. That means both Th1 and Th2 cytokines rise instead of the Th2 tendency of cytokines secretion in natural infection. Gene immunization has induced both humoral and cellular immune response gainst mimic epitopes of HVR1 Of HCV. Strong foundation has been built for the study of gene immunization of mimic epitopes of HVR1 of HCV...