MONOCLONAL-ANTIBODIES DEMONSTRATE ACCESSIBLE HA2 EPITOPES IN MINOR SUBPOPULATION OF NATIVE INFLUENZA-VIRUS HEMAGGLUTININ MOLECULES

Haemagglutinin (HA) was detected on the surface of influenza virus inf ected cell with monoclonal antibodies (MAbs) against both HA glycopoly peptides, HA1 and HA2, however, the reactivity of HA2-specific MAbs wa s remarkably lower as compared with HA1-specific MAbs. Quantitative an alysis with two MAbs, IB8 (anti-HA1) and IIF4 (anti-HA2) respectively, revealed that HA2 epitope was reachable for antibody only in minor su bpopulation of the HA representing approximately 7% of all molecules ( spikes). The basis of the HA heterogeneity is discussed.