Presence of A/Equi-2 Hemagglutinin and Neuraminidase Antibodies in Man

Abstract

Serum antibodies to envelope antigens of A/Equi-2 virus were determined in persons of various ages with no known exposure to human A2/Hong Kong/68 virus. Antibody to neuraminidase and hemagglutinin antigens was observed predominantly in persons born before 1900. These results raise the possibility that A/Equi-2 influenza virus originated in the human host.