EVALUATION OF MONOCLONAL-ANTIBODIES FOR SUBTYPING OF CURRENTLY CIRCULATING HUMAN TYPE-A INFLUENZA-VIRUSES

The hemagglutinin subtype specificities of six monoclonal antibodies ( MAbs) to influenza type A viruses were evaluated in a rapid culture as say by immunoperoxidase staining, Confluent monolayers of MDCK cells i n multiwell plates were inoculated with (i) 23 reference viruses, (ii) 200 isolates collected during the influenza season 1995 to 1996, and (iii) 28 clinical specimens previously found to be influenza virus pos itive, After overnight incubation, the cells were fixed and stained wi th MAbs IVA1/B10, IIF4/D3, 12L/5, 13L/6, 18L/1, or 18L/4, Type-specifi c MAbs were included as controls, All antibodies gave intensive cytopl asmic staining,vith infected cells in the absence of any reaction with uninfected cells, MAbs 12L/5, 13L/6, 18L/1, and 18L/4 exclusively rea cted with viruses of the subtype H1, and the antibodies IVA1/B10 and I IF4/D3 exclusively reacted with viruses of the subtype H3, None of the se MAbs reacted with viruses of the H2 subtype or with influenza type B viruses, Of the 200 recent isolates, 63 were identified as influenza virus type A, subtype H1, 95 were identified as type A, subtype H3, a nd 41 were identified as type B, One isolate contained a mixture of a type A (H3) and a type B influenza virus, Of the 28 previously positiv e clinical specimens, 15 contained an influenza virus A, subtype H3, 1 contained an influenza virus A, subtype H1, and 9 contained an influe nza B virus, The subtype of a very weakly positive specimen could not be determined, and two specimens remained negative, The MAbs described here allow for a rapid typing and subtyping of influenza virus isolat es and for the type- and subtype-specific detection of influenza virus es in clinical specimens.