[Antigenic characteristics of influenza virus protein M. The ELISA detection of the differences in the M proteins of remantadine-sensitive and -resistant variants of the virus].

Antigenic characteristics of influenza A virus M protein were studied by ELISA using a monospecific antiserum to M protein and monoclonal antibodies to the B4 and A7 antigenic determinants of M protein. The design of the test systems for M protein detection was based on the indirect and "sandwich" variants of ELISA as well as on the previously developed principle of blocking the indirect reaction. The latter variant of the test system had the highest specificity: 0.1--0.5 ng of specific protein. The high specificity of the method allows subtle antigenic differences of M protein within influenza A virus group to be detected. Comparative studies of remantadine-sensitive and resistant variants of the classic fowl plague virus showed the previously demonstrated significant differences in the physico-chemical properties of M protein of these variants to correlate with a marked antigenic divergence associated, in particular, with greater antigenicity of B4 epitope in M protein of remantadine-sensitive strains. The test system of ELISA blocking was found to be useful for M protein detection in virus-containing materials not subjected to purification and concentration (native allantoic fluids). The latter attests to the expedience of using ELISA in clinical diagnostic studies of influenza.