Analysis by Monoclonal Antibodies of H3N2 Subtype of Influenza A Viruses in Japan and South East Asia During 1980-1982

Four hybridomas secreting monoclonal HI antibodies to A/Bangkok/1/79 strain of Hong Kong (H3N2) subtype of influenza A virus were established. HI titers of the monoclonal antibodies were determined against 95 strains of the Hong Kong subtype isolated since 1968. Strains before 1976 were sharply distinguished from those after 1977, and strains after 1977 were divided into 4 or more groups with the HI test using the monoclonal antibodies. By HI tests using the culture fluids of four hybridome clones, following antigenic drifts of influenza A viruses in Japan and Thailand were sharply recognized. (1) A/Tokyo/1/77-variant was sharply distinguished from viruses before 1976, (2) A/Tokyo/1/77-variant was replaced with ABangkok/1/79-variant, (3) ABangkok/137 and 138/80 were the first isolates of A/kyoto/C-1/81-variant which prevailed in Japan in 1982, and (4) A/Niigata/102/81-variant was the other minor prevailing virus in 1982, which was first isolated as ABangkok/211 /81 in Thailand.