RESUMO
This study aimed to develop an effective experimental vaccine against highly pathogenic H5N1 Avian Influenza (HPAI) virus and to optimize their immunization programs. As reported previously, various DNA-based or recombinant vaccinia viral(Tiantan)-based H5N1 vaccine candidates, which containing a single cistronic construct (HAop, or NAop) or a bicistronic construct (HAop/M2 or NAop/M1) of H5N1 influenza virus (Anhui strain) were constructed and characterized in our lab. In this study, we further analysed the immunogenicity in mice of these vaccine candidates by various protocols (single or combined immunization). Our results showed that: comparing with immunization with DNA-based or rTTV-based H5N1 vaccine only, combined DNA-based with rTTV-based H5N1 vaccine immunization via prime-boost strategy enhanced immune response significantly against multi-H5N1 antigens detected by hemagglutination inhibition (HI) assay, NA- or M1- or M2-specific antibody detection, and micro-neutralizing antibody test and IFN-gamma ELISpot assay. Priming with DNA-based vaccine induced higher level of humoral response against HA or NA antigen than priming with rTTV-based vaccine; In contract, M1 and M2-specific antibody levels were higher among that of priming with rTTV -based vaccine. These findings provide a basis for further development of novel H5N1 vaccines and for the optimization of the immunization programs of combined multi-antigens vaccine candidates.