A Common Surface Antigen in Influenza Viruses from Human and Avian Sources

Abstract

Summary Serological cross-reactions were detected between four avian influenza viruses and a human A 2/57 virus and between an avian (TURKEY/CANADA/63) and an equine (EQUI 2/MIAMI/63) strain. The reactions were detected by strain-specific complement fixation tests and neuraminidase inhibition but not by haemagglutination-inhibition. Specific antiserum to the neuraminidase of an A 2/57 virus also reacted with the four avian viruses showing that it was the neuraminidase antigen on the avian and human A 2 virus that were antigenically closely related. The possibility that these viruses may have arisen by recombination between human and avian influenza viruses in nature is discussed.