Influenza virus consists of an 8-segment RNA genome. The non-structural (NS1) gene segment has been shown to accommodate large recombinant sequences, and recombinant influenza viruses retain the ability to infect mucosal tissue and stimulate innate immunity. We have developed a T-cell vaccine for HIV using influenza as a vector to generate a mucosal response in the genital mucosa and limit the initial focus of infection of HIV.
We have successfully developed recombinant influenza viruses, encoding the entire HIV-1 p24 capsid, HIV-1 p17 matrix, SIV p27 capsid and GFP (a control of similar insert size) genes into the NS segment of mouse-adapted PR8 (H1N1) and X31 (H3N2) influenza viruses. To express the viral NS1, nucleo-export protein (NEP) and antigens as separate proteins, intervening ‘2A’ ribosomal skip sequences were used. The influenza NS-segment is, thus, capable of multi-cistronic protein expression. MDCK cells and A549 lung epithelial cell lines infected with recombinant influenza PR8 and X31 viruses encoding the p24 and GFP proteins have shown robust expression of these proteins.
We hypothesise that the expression of HIV/SIV proteins from a recombinant influenza infection in the lungs will concurrently induce a CTL response in the genital mucosa. Immunogenicity studies in BALB/c mice will be performed, using a ‘priming’ vaccination with recombinant PR8 viruses, followed by a ‘booster’ vaccination with recombinant X31 viruses. The capacity to induce robust cellular responses in the spleen and lungs will be assessed using intracellular cytokine staining and tetramer assays. Cellular responses in the iliac lymph nodes draining the genital region will also be measured.