Rapid detection of respiratory syncytial virus in nasopharyngeal aspirates by direct immunofluorescence using monoclonal antibodies

Abstract

By examining nasopharyngeal aspirates (NPAs) collected during three successive winter epidemics of respiratory syncytial virus (RSV)-induced infantile bronchiolitis, we assessed the diagnostic value of a commercial monoclonal antibody-based direct immunofluorescence (IF) test for RSV antigens. This rapid assay was easy to read and more sensitive than virus isolation (sensitivities 1007 1071 (94%) versus 779 1071 (73%). The detection of RSV antigens in specimens negative by virus isolation probably reflected greater loss of infectious virus than of viral antigens during specimen transport or with increasing duration of the illness. When the IF test result was positive, virus isolation only rarely yielded viruses other than RSV (six isolates in 1020 specimens (0·6%)), and was therefore probably unnecessary. Virus isolation was valuable, however, when the IF result was negative or the specimen was unsuitable, as both RSV (89 isolates in 1525 specimens (6%) and other viruses implicated in bronchiolitis (e.g. parainfluenzaviruses, influenzaviruses, adenoviruses; 56 isolates in 1525 specimens (4%)) were frequently detected.