[Detection of the new influenza A subtype H1pdmN2 in a pig holding with severe respiratory symptoms].

Early in 2012 fattening pigs in a pig holding in northern Baden-Württemberg developed serious respiratory disease. After detecting Influenza A specific RNA by Real time-RT-PCR in the lung of an euthanized pig, virus isolation was achieved in embryonated chicken eggs. The haemagglutination-inhibition (HI) test performed on this isolate showed a reaction with H1N1 specific serum, so the strain was initially characterised as subtype H1N1. However, serum samples from convalescent pigs of the same stock four and six weeks later did not show any antibodies to H1N1 in HI test. However, using an ELISA, selected serum samples showed positive reactions against the highly conserved nucleocapsid protein. Performing an HI test using the isolated virus as antigen, significantly positive titers between 1:80 and 1:160 were obtained. The virus isolate was finally identified by molecular methods as a subtype H1pdmN2, a reassortant between the human pandemic (pdm) subtype H1N1/2009 virus and a swine influenza virus of the subtype HxN2.