In order to develop vaccine with stable efficiency against easily transforming virus such as influenza H5N1 virus, bioinformatic tools were 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 B-cell continuous and discontinuous epitopes on conserved domains of HA and NA antigens from H5N1 influenza A virus. To confirm the immunogenicity of these epitopes, genetic manipulating techniques have been employed, to prepare the recombinant epitopes in E. coli as a fusion form with H:1,2 flagellin antigen from Salmonella Typhimurium and with glutathione S-transferase. These recombinant antigens have been collected, purified and used for animal immunizing. This study shows the results in specific immunogenicity of recombinant B-cell epitopes continuous in chickens. Using HI test (Hemagglutination Inhibition Test), we could successfully prove that the antiserum from both of chicken groups immunized with GST-H:1,2-HeBc and GST-H:1,2-NeBc had specific antibodies could inhibit the agglutination of antigens derived from an influenza H5N1 virus strain isolated from infected chickens in Vietnam. The HI titer of anti-GST-H:1,2-NeBc antibodies was 113,00, that is 1,19 times higher than the HI titer of anti-GST-H:1,2-HeBc antibodies (95,00), while the HI titer of antibodies from chickens immunized with commercial inactivated vaccine H5N1 reached 291,58.
Protective immunity against influenza H5N1 virus challenge in mice by intranasal co-administration of baculovirus surface-displayed HA and recombinant CTB as an adjuvant