Poster Presentation International Veterinary Immunology Symposium 2016

Enhanced disease, but not cross-protection, following heterologous influenza challenge of vaccinated pigs is associated with an increase in pulmonary IL-17 and complement activation. (#134)

Holly R Hughes 1 , Phillip C Gauger 2 , Susan L Brockmeier 1 , Crystal L Loving 1
  1. USDA-ARS-National Animal Disease Center, Ames, IA, United States
  2. College of Veterinary Medicine, Iowa State University, Ames, IA, 50010

Vaccine associated enhanced respiratory disease (VAERD) has been described in pigs vaccinated with whole-inactivated influenza virus (WIV) and subsequently challenged with heterologous influenza A virus (IAV). Pathological changes in lungs of pigs with VAERD include significant lymphocytic infiltration and increased levels of proinflammatory cytokines. To better identify the mechanism(s) associated with VAERD versus partial-protection we defined the lymphocyte populations infiltrating the lungs following challenge, as well as level of complement activation. Pigs partially protected against infection had an increase in IFN-g producing memory T cells (CD4+CD8α+ double-positive), while pigs with VAERD had an increase in IFN-γ producing CD4 and CD4-CD8α- double-negative T cells compared to non-vaccinated, challenge controls. Additionally, IL-17A and complement activation was significantly higher in the lungs of pigs experiencing VAERD. These data suggest a role for the inflammatory IL-17A response and complement activation in the development of VAERD pathology, as well as differential activation of T cell populations.