Isolation of cross-reactive, subtype-specific monoclonal antibodies against influenza virus HA1 and HA2 hemagglutinin subunits.

The large (HA1) and small (HA2) subunits of influenza virus A/Vict/3/75 hemagglutinin were purified in denatured form by preparative electrophoresis. Both polypeptides were used to immunize mice from which monoclonal antibodies were obtained. These antibodies reacted not only with the corresponding hemagglutinin subunit but also with purified virions. When tested by radioimmunoassay against a panel of human viruses, most anti-HA1 and -HA2 antibodies behaved as subtype-specific, whereas anti-HA antibodies, raised against purified virus, were more restricted. The anti-subunit antibodies were negative in hemagglutination-inhibition and neutralization tests. The interest of these antibodies as reagents for research and diagnosis is discussed.