Synthesis and immunogenicity evaluating of a discontinuous B-cell epitope predicted from influenza virus A/H5N1 HA antigen

Abstract

To develop vaccine with stable efficiency against easily transforming virus such as influenza A/H5N1 virus, bioinformatic tools have been used to predict conserved epitopes from viral antigens to be used as materials for the development of polyvalent vaccine against this virus. Using this approach, we have successfully predicted one discontinuous B-cell epitope, a peptide of 14 aminoacids on conserved domains of HA antigen from H5N1 influenza A virus. In this study, we report results of the preparation of this discontinuous B-cell epitope as the recombinant fusion form with H:1,2 flagellin from Salmonella typhimurium to increase the immunogenicity of this epitope using genetic manipulating techniques with Escherichia coli as host cell. The immunogenicity of the chemically synthesized predicted epitope and the recombinant epitope was examined by immunization of each of these epitopes to mice. Using hemagglutination inhibition (HI) method, we successfully demonstrated that both anti-sera from mice immunized either with chemically synthesized peptide or with recombinant flagellin H:1,2 fused epitope could recognize and inhibit the agglutination of inactivated influenza H5N1 virus strains, such as A/H5N1/ Chicken13/ Vietnam/LA/2006 and A/Vietnam/CL26/2004 (H5N1) isolated from infected chicken and human in Vietnam.