An antigenic map of the haemagglutinin of the influenza Hong Kong subtype (H3N2), constructed using mouse monoclonal antibodies.

Panels of monoclonal antibodies were raised to the haemagglutinin of strains of the Hong Kong subtype of influenza (H3N2), namely Hong Kong 1968, England 1972, Port Chalmers 1973, Victoria 1975 and Texas 1977. The probable binding sites of individual antibodies in each panel were determined by correlation of cross-reactivity with 16 heterologous strains from the same subtype, and amino acid differences between their haemagglutinin molecules. This led to an approximation of the "average repertoire" of the BALB/c mouse to influenza type A haemagglutinin. Comparative data of the cross-reactivity of whole mouse sera suggested that the monoclonal panels derived from spleen cells were a fair representation of circulating antibody. Variation in the cross-reactivities of individual sera approached that of individual monoclonal antibodies. The relevance of this finding to selection of new virus variants in the human population was discussed. Heterospecific antibodies were detected in some monoclonal panels. Specific amino acid changes which could be responsible for such activity were identified.