Recombination of influenza A viruses of human and animal origin.

Simultaneous infection of the allantoic sac of the chick embryo with influenza A/equine 1/56 and any of three recombinants derived from human influenza viruses produced stable hybrids with antigens from each parent strain. These hybrids contain the hemagglutinin protein of the equine virus and the neuraminidase of the human strains. The experiments demonstrate genetic homology of human and equine influenza A viruses and suggest the possibility of their recombination in nature.