Natural killer T cell adjuvanted inactivated swine influenza virus vaccine enhanced the viral load and suppressed the host immune response to pandemic 2009 H1N1 virus in pigs (P6093)

Abstract

Abstract Swine influenza virus (SIV) causes an acute respiratory disease in pigs, and pigs are infectable by both avian and mammalian influenza viruses. Activation of NKT cell induces heterologous protection against influenza viruses in rodent studies. We discovered CD1d-restricted NKT cell in pigs. Aim of this study was to determine the efficacy of UV-inactivated bivalent SIV vaccine, comprising of triple reassortant zoonotic H1N1 (Sw/OH/24366/07) and H3N2 (Sw/OH/04) viruses; coadministered intranasally with NKT cell adjuvants, phosphatidylinositolmannosides-2 (PIM2) and α-Galctosylceramide (α-GalCer). In vaccinated homologous H1N1 virus challenged pigs, reduced viral load in the lungs associated with increased IFN-γ+ lymphocytes in the lungs and tracheobronchial lymph nodes by ELISPOT, and an increase in IFN-γ+CD8+ and IFN-γ+ γδ T cells was observed. Further, increased virus specific IgA response in the BAL fluid and enhanced lung NK cell-cytotoxicity was detected. However, in vaccinated pandemic 2009 H1N1 virus challenged pigs, enhanced nasal viral shedding and lung viral load was detected. Immunologically, reduced frequency of total lymphocytes and CD8+ T cells, and reduced frequency of total IFN-γ+ T cells was detected in the lungs. In conclusion, NKT cell adjuvanted inactivated SIV vaccine in pigs enhanced the pandemic 2009 H1N1 replication and dampened the anti-viral immune response.