Mitogenicity of influenza hemagglutinin glycoproteins and influenza viruses bearing H2-hemagglutinin.

The hemagglutinin glycoprotein is responsible for the mitogenic effect of influenza A viruses of the H2N2 subtype. This was indicated by the ability of viruses bearing the H2-hemagglutinin glycoprotein, regardless of its associated neuraminidase, to induce lymphocyte proliferation in normal spleen cell suspensions and by the ability of antisera with specificity for the H2-hemagglutinin to block this response. Moreover, purified hemagglutinin from representative viruses from the H0N1, H1N1, H2N2, H3N2, and influenza B subtypes were also shown to be mitogenic.