Rapid diagnosis of respiratory syncytial virus infection by antigen immunofluorescence detection with monoclonal antibodies and immunoglobulin M immunofluorescence test.

During a respiratory syncytial virus (RSV) infection outbreak in a pediatric hospital, diagnosis was made by immunofluorescence on smears by using an anti-RSV monoclonal antibody (IFm). Immunoglobulins M and G were titrated by indirect immunofluorescence on HEp-2 cells infected with an RSV strain. The IFm was sensitive (89%) and specific (75%) when compared with the cell culture method. We showed that the specimens which were found positive by IFm and negative by cell culture were truly positive. Under these conditions, the IFm test appears more sensitive and more specific than cell culture, particularly when no care is taken to maintain the specimens in the cold during transport. In this study the immunoglobulin M immunofluorescence test had a low sensitivity (34%), especially on serum samples taken on days 0 to 4 after the onset of illness.