Monoclonal antibodies for the rapid diagnosis of influenza A and B virus infections by immunofluorescence.

Mouse monoclonal antibodies, directed against antigenic sites on influenza A and B viruses and found to be type-specific in an immunoassay, were assessed for use as diagnostic reagents in an indirect immunofluorescence assay on nasopharyngeal secretions. The influenza A antibodies were directed against nucleoprotein or matrix protein antigens and the influenza B antibodies against nucleoprotein and haemagglutinin antigens. The influenza A anti-matrix monoclonal antibody was found to give a strong intranuclear particulate fluorescence in normal baboon kidney cells and cells from nasopharyngeal secretions negative for influenza A virus, including those from a patient infected with respiratory syncytial virus. Pools of the remaining monoclonal antibodies gave satisfactory results on 25 specimens from patients with influenza A H1N1 and H3N2 subtypes and 12 from patients with influenza B.