Recombinant influenza virus as a vector for HIV antigens

OBJECTIVE: To develop a recombinant influenza virus as a vaccine vector for HIV antigen p17. To characterize the protein expression from the antigen inserted in the vector and to investigate the capacity of the vector to activate T cells in vitro and to induce antibody formation in vivo. DESIGN AND METHODS: The recombinant influenza vector for HIV antigens was constructed from eight influenza gene segments by molecular biology techniques. The influenza neuraminidase gene was replaced by the HIV antigen of interest. Protein expression from the construct was analyzed by western blot and by LC-MS/MS. Antigen-presenting cells were infected with the viral vector and co-cultured with T cells and T-cell activation was measured by cytokine production. The presence of antibodies specific for HIV in serum of mice vaccinated with the vector was analyzed by antibody assays. RESULTS: HIV antigens are expressed from the constructed recombinant influenza vector. Both the conventional western blot analysis and the more flexible LC-MS/MS method are suitable for detection of antigen expression from a viral vector. Antigen-presenting cells infected with the viral vector are able to present the HIV antigen to T cells through which HIV-specific T cells become activated. Mice immunized twice with the vector developed antigen-specific antibody responses. CONCLUSION: HIV antigens inserted into recombinant influenza are expressed from the viral vector, can activate antigen-specific T cells in vitro as well as induce antibody formation in vivo. Recombinant influenza viruses are promising vector candidates that may be used for the induction of antibody and T-cell mediated immune responses.