Date of Award
Master of Science
Veterinary Microbiology and Preventive Medicine
Live-attenuated influenza virus (LAIV) vaccines provide broader cross-protection than whole-inactivated virus (WIV) vaccines against influenza A virus (IAV) in swine. However, standard correlates of protection, such as serum hemagglutination inhibition (HI) antibody titers, do not accurately predict cross-protective efficacy provided by LAIV vaccines. While the contribution of T cells to IAV immunity is appreciated, data comparing methods to evaluate IFN-g production by IAV-specific T cells is limited. To understand the differential immunogenicity between LAIV and WIV vaccines as it relates to induction of T cell responses, IFN-g production by peripheral T cells following antigen restimulation was assessed post-vaccination. ELISpot assays used to enumerate IAV-specific IFN-g secreting cells (SC) in peripheral blood 42 days post-vaccination (dpv) indicated that WIV-vaccinated pigs had a greater number of IFN-g SC compared to LAIV vaccinated pigs, regardless of recall IAV used. In LAIV vaccinates there was no change in the number of IFN-g SC to homologous IAV when comparing responses at 77 dpv to 42 dpv, but a decrease over time in WIV vaccinates. Pig age at time of WIV vaccination significantly effected peripheral IAV-specific IFN-g recall responses. In only one instance were statistical differences between vaccine groups different between the ELISpot and ELISA, in all other cases, the same conclusion was made in regards to responses. Collectively, these data indicate that peripheral IAV-specific IFN-g recall responses are not predictive of LAIV vaccination status, nor a useful surrogate for predicting cross-protection. However, the evaluation of IFN-g recall responses may be useful for investigating factors, such as animal age or vaccine formulation that can affect immune responses to WIV vaccination.
Zahra F. Olson
Olson, Zahra F., "Differential measures of cellular IFN-γ responses in swine following influenza vaccination" (2014). Graduate Theses and Dissertations. 14221.