Serological evidence of natural recombinant influenza virus (Hsw1N2) infection among pigs in Japan.

A new recombinant influenza A virus (Hsw1N2) infection among hogs in Miyagi prefecture, Japan, was confirmed by serological examinations. Nineteen out of twenty sera collected in one farm in January 1979 showed high haemagglutination inhibition antibody titres to Hsw1 antigen (A/New Jersey/8/76) and also significant neuraminidase inhibition antibody titres to N2 antigen of the Hong Kong 1973 variant (A/Port Chalmers/1/73) but not to N1 antigen. The results indicate the occurrence of genetic reassortment between Hsw1N1 and H3N2 viruses in Japanese pigs and spread of the recombinant in nature.