Monoclonal antibodies to glycopolypeptides HA1 and HA2 of influenza virus haemagglutinin.

Anti-haemagglutinin monoclonal antibodies were prepared and their HA1 or HA2 specificity was determined by solid phase radioimmunoassay (RIA) using purified viral haemagglutinin (HA) and haemagglutinin glycopolypeptides HA1 and HA2, by radioimmunoprecipitation followed with SDS-PAGE, by immunoblotting and by inhibition of virus-induced haemagglutination. The capacity of these methods to estimate HA1 or HA2 specificity of anti-HA monoclonal antibodies (MoAb) was compared. HA1 specificity was demonstrated for all hybridomas originating from lymphocytes of mice immunized with complete influenza virus, except IIF4 hybridoma which was HA2-specific. All hybridomas obtained with lymphocytes from mice immunized with HA glycopolypeptide HA2 were HA2-specific. Anti-HA2 MoAb neither inhibit haemagglutination induced by the virus or by HA subunits nor neutralized viral infectivity, either alone or in mixture. As expected, all anti-HA1 MoAb were H3 subtype-specific, showing usually good reactivity only with viruses close to the virus strain used for immunization. Two anti-HA1 MoAb (IVA1 and IVG6) showed unusual cross-reactivity within the H3 subtype. All anti-HA2 MoAb were broadly cross-reactive within the H3 subtype. Moreover, a half of them showed high cross-reactivity with influenza viruses of the H7 HA subtype. But the same antibodies did not react with HA of H1, H2 and H8 subtypes.