The project comprises: 1) Surveillance of recent swine influenza strains with the purpose to detect viruses differing in antigenic composition or virulence; 2) Vaccination challenge experiments in order to determine whether updating of the currently used influenza virus strains by more recent strains is advisable; 3) Studies on the importance of H1N2 swine influenza viruses in Belgium: antigenic characterisation of circulating strains; pathogenesis and cross-protection studies; 4) Study of the role of proinflammatory cytokines in influenzavirus-mediated disease in pigs; in vitro study of the mechanisms of cytokine induction by the virus.