Rapid Diagnosis of Respiratory Syn.cytial Virus Infection by Immunofluorescent Antibody Techniques

Abstract

Present methods of diagnosing respiratory syncytial virus infection by isolation and identification in tissue culture takes from 10 to 28 days. An immunofluorescent technique was used for the rapid detection of respiratory syncytial virus in: (a) cells scraped from three inoculated tissue culture tubes at intervals during the first seven days of culture; (b) direct smears from throat swabs; and (c) aspirated nasopharyngeal secretions from children with bronchiolitis. A fluorescent antibody technique was also used to confirm that early cytopathic effects were due to respiratory syncytial virus. Materials used for the fluorescent antibody technique were: acetone for fixation; a respiratory syncytial virus antiserum, prepared in rabbits, absorbed with human tissue culture cells; and a fluorescein labelled anti-rabbit globulin (Fluoroscan Plus). Three out of six nasopharyngeal secretions gave positive fluorescent antibody results on the same day that the patient was admitted to hospital. Five tissue culture tubes were inoculated with cough swab material from each of the 16 cases. Two tubes were used for conventional isolation techniques and three were examined by fluorescent antibody technique. Twent-five per cent. of the latter were positive on the second day and 50% within seven days by the fluorescent antibody technique. Examination of direct smears by fluorescent antibody techniques were unsatisfactory. Preliminary results suggested that, by the early examination of nasopharyngeal secretions and tissue culture cells by the fluorescent antibody technique, a virological report could be available as early as a report on bacterial isolations and sensitivities. This would give early guidance on management of cases, and will also be of particular use if anti-viral drugs become available. We wish to thank Professor S. D. M. Court for his help and encouragement in this work. We are grateful to the paediatricians at all hospitals and to their ward sisters and medical staff for their co-operation and to Miss P. M. Sturdy for the collection of specimens. Special thanks are due to the Scientific and Research Subcommittee of the Royal Victoria Infirmary and to the Medical Research Council for grants which made this work possible. We also wish to thank Winthrop Biologicals Limited for their reagents. © 1968, British Medical Journal Publishing Group. All rights reserved.