Detection of respiratory syncytial virus antigen in nasopharyngeal secretions by Abbott Diagnostics enzyme immunoassay

Abstract

We compared a rapid respiratory syncytial virus (RSV) antigen enzyme immunoassay (EIA) (Abbott Diagnostics, North Chicago, Ill.) with virus culture and with the indirect fluorescent-antibody test (FAT) by using nasopharyngeal washings from children with suspected RSV pneumonia or bronchiolitis. Fresh washings were used in ail three tests. Specimens were inoculated into HEp-2 cells and human embryonic lung fibroblasts and observed for cytopathic effect. Cells in the centrifuged sediments of the nasal washes were examined for typical cytoplasmic fluorescence of RSV by FAT. The EIA cutoff was an optical density (OD) at 492 nm that was greater than the mean OD of the negative controls plus 0.1. An OD within +20% of the cutoff was considered borderline, and these specimens were retested. Of 289 specimens, 118 (41%) were positive by culture, 150 (52%) were positive by FAT, and 154 (53%) were positive by EIA. Eight borderline EIAs were all negative when the specimens were retested after storage at-70°C. Of 17 specimens positive by EIA but negative by culture and FAT, 9 were blocked in a competitive EIA, indicating that they were true-positives and that the culture and FAT were falsely negative. The sensitivity, specificity, and predictive value (positive) of the EIA versus culture, FAT, or blocking assay were 90, 94, and 95%, respectively. We conclude that the Abbott RSV antigen EIA is highly sensitive and specific.

Rapid detection of respiratory syncytial virus and influenza A virus in cell cultures by immunoperoxidase staining with monoclonal antibodies

“…After staining, however, infected cells were easily -i s detected by microscopy and, occasionally, even with the naked eye. In contrast to the results of Masters et al (11), our observations implicate the usefulness of the testing of negative cultures for a maximum yield of RSV isolates. Simultaneous use of several cell lines has been suggested for optimal recovery of RSV in clinical specimens (2).…”

“…The availability of specific antiviral therapy for the treatment of infections with respiratory syncytial virus (RSV) and influenza A virus has resulted in an emphasis on the importance of a rapid diagnosis of these pathogens (8,12,19). Immunofluorescence microscopy and immunoassay techniques have been developed for direct detection of infected cells or viral antigens in clinical specimens (6,9,11,15,16,22,23). However, virus isolation is still the standard reference method for the evaluation of new alternatives (10).…”

Detection of respiratory syncytial virus antigen in nasal washings by Abbott TestPack enzyme immunoassay

“…Immunofluorescence requires special equipment and considerable expertise on the part of the microscopist (4, 6). Early RSV EIAs were generally insensitive (5,10), but recently introduced commercial RSV EIA kits appear to be more sensitive (1,8,9,13).…”

Evaluation of a monoclonal antibody pool for rapid diagnosis of respiratory viral infections

“…The MAbP did not detect two RSV isolates. Both RSV isolates missed by the MAbP had syncytia upon initial isolation; one had syncytia upon reisolation, and one was DFA positive (Table on September 13 1). Of the five RSV isolates missed by routine reference techniques, one showed no CPE, twd had questionable CPE, and two were contaminated.…”

“…Virus isolation can take up to 14 days for some respiratory viruses, including adenoviruses (AD), parainfluenza viruses, and respiratory syncytial virus (RSV). ELISA for RSV performed directly on nasopharyngeal specimens is commercially available (2,8,10,12,13,20), but it is not available for other respiratory viruses. Fluorescent-antibody staining performed directly on nasopharyngeal specimens (DFA) has been applied to all respiratory viruses with various degrees of sensitivity and specificity (1, 5, 8, 10, 11, 15, 17-19, 21, 22).…”