[Hemagglutinin antigens of influenza viruses isolated from man and birds]

Immunological analysis has shown hemagglutinins of avian viruses like hemagglutinins of human viruses to have a complex antigenic composition. Three antigenic determinants were discovered in hemagglutinin of A/Chicken/12/71 virus previously designated H3 and in hemagglutinin of A/Tern/18/73 virus previously designated Hav7. The H3 determinant and the second determinant are identical in avian and A/Hong Kong/1/68 human viruses. In addition, hemagglutinins of avian viruses have a determinant specific for each virus which is lacking in human influenza virus hemagglutinin.