Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/13/2014
Publication Date: N/A
Technical Abstract: Controlling influenza A virus (IAV) in swine has become increasingly difficult with the emergence of novel reassorted strains and introduction of human seasonal IAV into pigs. In North America there are six antigenically distinct H1 subtypes currently circulating in pigs. Live-attenuated influenza virus (LAIV) vaccines provide broader cross-protection than whole-inactivated virus (WIV) vaccines making LAIV a candidate for next-generation swine IAV vaccines. However, a defined immune correlate or standardized assay has not been identified to predict cross-protection following LAIV vaccination. Hemagglutination-inhibiting (HI) immunoglobulin (Ig) in serum has long been the gold standard correlate of protection following WIV vaccination; however, LAIV does not elicit a robust serum HI Ig titer. Oral fluids (OF) have become a rapidly developing diagnostic specimen for a variety of animal pathogens. In order to evaluate mucosal immunogenicity and identify a potential correlate of protection, groups of pigs were vaccinated with different LAIV vaccines encoding pandemic surface genes and subsequently challenged with a heterologous beta-cluster or gamma-cluster IAV. Following vaccination nasal wash (NW) and OF were collected to evaluate Ig levels against a panel of H1 viruses. Both NW and OF had detectable levels of IAV-specific Ig when measured by whole-virus ELISA. Higher IAV-specific IgA endpoint titers were associated with reduced virus shedding following challenge with heterologous IAV. These data suggest OF can serve as a sample for evaluating LAIV immunogenicity and predicting cross-protection.