Respiratory Syncytial Virus In Nasopharyngeal Aspirates Research Articles

Hospitalization for respiratory syncytial virus in the paediatric population in Spain.

The aim of this population-based retrospective study was to determine the incidence of hospitalization for community-acquired, laboratory-confirmed respiratory syncytial virus (RSV) infection in an unselected paediatric population from southern Europe. The study was performed in an area with 15,700 children aged less than 5 years attended by a single hospital. The presence of RSV in nasopharyngeal aspirates from children with acute respiratory infection treated in the hospital was investigated in four seasons (July 1996-June 2000). A total of 390 episodes of hospitalization for RSV infection were detected and 83.3% of the children were aged less than 1 year old. The annual hospitalization rate was 37/1000 for infants aged less than 6 months and 25/1000 for those aged less than 1 year. During the study period, 2.5% of the infants younger than 1 year and approximately 5% of those younger than 3 months were hospitalized for RSV infection. The mean length of hospital stay was 5.9 days. Seven per cent of the patients required admission to the intensive care unit and more than half of these children were aged less than 1 month. In Spain, community-acquired RSV infection is a highly frequent cause of hospitalization in young children, especially in those aged less than 1 year. Prevention of RSV infection, through the development of vaccines and/or other strategies, should be a public health priority.

Infection à virus respiratoire syncytial. Amplification génomique, immunofluorescence et culture

Summary Respiratory syncytial virus (RSV) is the most common cause of respiratory illness during human infancy, particularly among infants under 6 months of age. At the laboratory of Virology at the CHR-Rouen we have developed a method of viral detection based on reverse transcription (RT) and amplification of viral nucleic acid sequences by the polymerase chain reaction (PCR). This procedure was used to screen for RSV in nasopharyngeal aspirates from children with suspected respiratory infections between January and May 1993. Sixty patients under one year of age were included in the study. The PCR approach was compared to classic methods of diagnosis : the results were in good agreement. PCR also identified whether the virus was type A or B. But PCR is laborious, difficult and very expensive. It is still better suited to research than diagnosis.

Validation of respiratory syncytial virus enzyme immunoassay and shell vial assay results

The Pathfinder respiratory syncytial virus (RSV) enzyme immunoassay (EIA) (Kallestad), the shell vial (SV) technique, and conventional cell culture (CC) were compared for detection of RSV in nasopharyngeal aspirates. We found sensitivities, specificities, and positive and negative predictive values of 58.4, 100, 100, and 68.2%; 80.7, 97.2, 97.0, and 81.9%; and 77.6, 97.2, 96.9, and 79.5% for the CC, EIA, and SV methods, respectively. The SV and EIA techniques were both more sensitive than CC (P < 0.001). Finally, 29 respiratory viruses other than RSV were identified by CC.

Time-resolved fluoroimmunoassay compared with virus isolation for rapid detection of respiratory syncytial virus in nasopharyngeal aspirates.

Two monoclonal antibodies against two distinct conserved epitopes of the respiratory syncytial virus (RSV) nucleocapsid protein were used in a direct time-resolved fluoroimmunoassay (TR-FIA) for the detection of RSV antigens in nasopharyngeal aspirates. The capture antibody was adsorbed to the solid phase of microdilution strip wells, and the indicator antibody was labeled with a europium chelate. Specimens and label were incubated simultaneously for 1 h at 37 degrees C in the coated wells. After the test samples were washed, fluorescence enhancement solution was added, strips were shaken, and the time-resolved fluorescence was measured. The test procedure took only 75 min, and the total time for 20 specimens, with pretreatment by sonication, was 2 to 3 h. We prospectively evaluated the detection of RSV in nasopharyngeal aspirates of pediatric patients by TR-FIA and by virus isolation in human diploid fibroblasts. TR-FIA detected 40 of 42 isolation-positive specimens. Nine additional isolation-negative specimens were positive by TR-FIA; all proved to be true positives by a blocking-type confirmatory assay. The sensitivity, specificity, positive predictive value, and negative predictive value for TR-FIA were 95, 96, 82, and 99%, respectively, of the values obtained by virus isolation and 96, 100, 100, and 99%, respectively, of the values obtained by virus isolation and the confirmatory assay.

The detection of respiratory syncytial virus in nasopharyngeal aspirates: Assessment, formulation, and evaluation of monoclonal antibodies as a diagnostic reagent

Comparisons were made between standard methods of cell culture, indirect immunofluorescence (IF) using hyperimmune respiratory syncytial virus (RSV) antiserum, and indirect IF using mouse monoclonal antibodies directed against various epitopes of RSV for the detection of RSV in nasopharyngeal aspirates. The monoclonal antibodies were used singly and in pools of different specificities which in turn were tested in both direct and indirect IF. In a preliminary study, aspirates from 227 infants were examined for RSV by standard methods. The results were compared with the detection of RSV in these aspirates using nine separate monoclonal antibodies and a pool consisting of five monoclonal antibodies. Respiratory syncytial virus was detected in 64 (28%) by cell culture, in 68 (30%) by indirect IF using bovine polyclonal antibody (BPA), and in 75 (33%) by indirect IF using the monoclonal antibody pool. The nine individual monoclonal antibodies when tested separately were less sensitive, detecting between 8 and 77% of all aspirates found to be positive by culture. After statistical analysis of the results obtained in the preliminary study, a refined monoclonal antibody pool was prepared and in a further study was tested by both direct and indirect IF in parallel with our two standard methods. Slides prepared from 303 nasopharyngeal aspirates collected between 1981 and 1984 and either tested the same day or stored at -20 degrees C were used to evaluate these reagents. Overall agreement between the four tests was found in 274 (90%) specimens. Cell culture detected RSV in 68 (22%) specimens, indirect IF with BPA in 67 (22%), indirect IF with monoclonal antibody in 72 (24%), and direct IF with monoclonal antibody in 79 (26%). The pool of monoclonal antibodies used in direct or indirect IF was thus more sensitive than our standard methods for the detection of RSV in nasopharyngeal aspirates, and direct IF tests could be completed in 40 minutes.