ARS | Publication request: Immune responses elicited to a live-attenuated influenza virus vaccine compared to a traditional whole-inactivated virus vaccine for pandemic H1N1in pigs

Submitted to: Keystone Symposia
Publication Type: Abstract Only
Publication Acceptance Date: December 27, 2010
Publication Date: February 26, 2011
Citation: Loving, C.L., Vincent, A.L., Pena, L., Perez, D. 2011. Immune responses elicited to a live-attenuated influenza virus vaccine compared to a traditional whole-inactivated virus vaccine for pandemic H1N1 in pigs [abstract]. Keystone Symposium, Immunity in the Respiratory Tract. Poster No. 228. p. 163.

Technical Abstract: In the United States there are currently two influenza vaccine platforms approved for use in humans - conventional inactivated virus and live-attenuated influenza virus (LAIV). One of the major challenges for influenza vaccination is designing a platform that provides cross-protection across strains. Pandemic H1N1 influenza (pH1N1) swept across the globe in 2009 and crossed the species barrier, infecting swine in several countries. Pigs are a natural host for influenza virus and serve as a model for evaluating immune responses following vaccination and challenge. Recently, a live-attenuated vaccine (LAIV) was developed by introducing modifications in the polymerase genes of a swine-like triple reassortant (tr) virus (Pena et al, 2010). A single intranasal dose in pigs provided sterilizing immunity upon intratracheal challenge with virulent pH1N1 virus. In addition, a single immunization induced a strong cell-mediated immune response characterized by an increased number of IFN-gamma secreting cells and expanded T-cell populations when compared to pigs vaccinated with a whole inactivated virus (WIV) vaccine. Following challenge, there was a significant increase in the percentage of CD4/CD8 double-positive memory T-cells in LAIV vaccinated pigs compared to WIV vaccinated pigs. In addition, there was a significant increase in the percentage of proliferating cells in the LAIV group compared to the WIV group following restimulation with pH1N1 in vitro. Taken together, these results indicate the tr-LAIV vaccine elicits a robust cell-mediated immune response and sterilizing immunity to pH1N1 infection.