Location: Virus and Prion Research
Project Number: 5030-32000-231-098-R
Project Type: Reimbursable Cooperative Agreement
Start Date: May 1, 2022
End Date: Mar 31, 2025
Aim 1. To generate and characterize live attenuated influenza virus (LAIV) vaccines modified for broad cross protection against influenza viruses in swine. Aim 2. To determine the safety and characterize the immune response stimulated by the LAIV vaccines in swine. Aim 3. To determine the efficacy of the LAIV vaccines in swine against antigenically distinct viruses.
The LAIV vaccines will be generated through cloning and reverse genetics, and further modified to express two immunomodulatory proteins. Three vaccine viruses will be generated and growth kinetics experiments and serial passages will be performed in vitro to determine the stability of the vaccine strains. Protein expression will be assessed by western blotting. A swine study will be performed with all three vaccines to determine safety and immunogenicity. Results will be compared to a commercial inactivated vaccine. Each vaccine will be administered using a prime-boost strategy two weeks apart. Serum, peripheral blood mononuclear cells, nasal wash, and bronchoalveolar lavage fluid will be analyzed 7 days post vaccination, 7- and 28-days post boost. Antibody levels will be determined using ELISA and Hemagglutination inhibition assays and cellular response will be evaluated by ELISPOT and flow cytometry after recall stimulation. Bronchus-associated lymphoid tissue and nasal- associated lymphoid tissue will be collected for flow cytometry and histological analyses of B and T cell populations. An in vitro study will be performed to test the reassortment potential of the LAIV vaccine viruses by co-culturing the vaccine viruses with a wild-type homologous strain and colonies will be screened after incubation. An additional swine study will be performed to determine the efficacy of the LAIV vaccines in swine. Vaccinated and unvaccinated control pigs (n=10/group) will be challenged with H1N1 or H3N2 heterologous virus, and clinical signs and viral shedding will be evaluated. Pigs will be euthanized at 5 days-post challenge and viral titers in lungs and lung lesions will be evaluated.