Antigenic Composition of Recombinant Virus Strains Produced from Human and Avian Influenza A Viruses

Summary The antigenic structure of a recombinant virus, FPV-A2 (r4), obtained by the interaction of an avian and a human influenza A virus was investigated by means of haemagglutination-inhibition, neuraminidase-inhibition and immunoprecipitation tests. The neuraminidase of the recombinant was found to be antigenically identical to that of its A2/singapore/1/57 parent whilst its haemagglutinin was identical to that of fowl plague virus, the other parent. Similar studies on a recombinant obtained by the interaction of two avian influenza A virus strains, fowl plague virus and A/turkey/massachusetts/65 virus, indicated that it contained neuraminidase of the antigenic type found in the turkey virus and haemagglutinin like that of fowl plague virus. A/turkey/massachusetts/65 was selected for study since its neuraminidase is antigenically closely related to that of human A2 virus strains. Studies on the electrophoretic mobilities of the structural proteins of FPV-A2 (r4) indicated that it contained structural components derived from each parent and thus supported the immunological findings. The significance of these findings in relation to possible genetic interactions between human and avian influenza viruses in nature is discussed.