ANALYSIS OF MONOCLONAL IMMUNE-RESPONSE TO INFLUENZA-VIRUS .2. ANTIGENICITY OF VIRAL HEMAGGLUTININ

The antigenicity of the hemagglutinins (HA) of 5 influenza viruses of the A0 and A1 subtypes was analyzed by means of monoclonal antibodies of murine origin produced in vitro. Secondary monoclonal anti-HA(PR8) antibodies were able to differentiate 14 antigenic determinants (or groups of determinants) on the HA of 5 influenza virus strains of the A0 and A1 subtypes. Taking into account that certain pairs of determinants delineated on heterologous HA may reflect the heterogeneity of the humoral immune response to a single homologous determinant, the presence of at least 8 determinants (host cell-derived determinants not included) on the homologous HA of PR8 and probably on the HA of influenza viruses in general is postulated. Three types of HA-determinants of A0 and A1 influenza virus strains could be distinguished: strain-specific, partially shared, and determinant(s) common to all 5 virus strains tested. Roughly 40, 55 and 5%, respectively, of the secondary anti-PR8 antibodies of BALB/c mice were directed against determinants belonging to either of the 3 types.