Genetic characterization of respiratory syncytial viruses isolated from consecutive acute respiratory infections in a HIV infected child.

BACKGROUND: Human respiratory syncytial virus (HRSV) was isolated from a 2-year-old child suffering from perinatally transmitted AIDS in the course of three distinct episodes of respiratory infections. The first episode occurred in the winter of 1994, the following two episodes of cough and fever occurred two and 4 months after the initial episode. OBJECTIVE: To analyze the genetic variability of the child's HRSV strains, and with contemporary circulating HRSV isolates. RESULTS: The three child's HRSV isolates belonged to group B. Sequence analysis of the attachment (G) protein gene (which has the highest degree of antigenic and genetic diversity in HRSV), demonstrated no difference in the sequence obtained from the three isolates recovered from the child. Comparison of the child's HRSV strain with contemporary circulating group B HRSV isolates showed a close sequence similarity with one of them. CONCLUSIONS: The immunodeficiency in an HIV-positive child may have resulted in the recurrent isolation of one HRSV strain. Although it cannot be discarded the possibility that the recurrent episodes might be re-infections, it is unlikely in view of the lack of change in the HRSV glycoprotein G. This is the first study that analyzes the genetic variation in HRSV isolates from consecutive respiratory disease episodes in an immunosuppressed patient.

Evaluation of the QuickLab RSV test, a new rapid lateral-flow immunoassay for detection of respiratory syncytial virus antigen.

Rapid respiratory syncytial virus (RSV) diagnosis is vital to the prevention of nosocomial RSV infections. We evaluated a new rapid lateral-flow RSV immunoassay, the QuickLab RSV test, that requires use of only one reagent. We compared QuickLab to the Directigen RSV (DIR) assay, which requires six reagents, and direct fluorescent antibody (DFA) testing. DFA results were considered the "gold standard." For 133 nasopharyngeal aspirates tested, DFA results were 77 (57.8%) positive, 47 (35.3%) negative, and 9 (6.8%) indeterminate. The sensitivities, specificities, positive predictive values, and negative predictive values of QuickLab and DIR tests were 93.3% (70 of 75) and 80.8% (59 of 73), 95.6% (43 of 45) and 100.0% (46 of 46), 97.2% (70 of 72) and 100.0% (59 of 59), and 89.6% (43 of 48) and 76.7% (46 of 60), respectively. QuickLab was significantly (P = 0.02) more sensitive than DIR; the difference in specificities was not significant. DFA was more sensitive than DIR (P < 0.001) but not more sensitive than QuickLab (P = 0.45). The results of DIR testing were initially uninterpretable and required retesting with 15% of the specimens compared to 3% of QL results (P < 0.001). We conclude that the QuickLab RSV test has sensitivity similar to that of the DFA assay and better than that of the DIR assay. QuickLab testing is also simpler to perform and interpret than both DFA and DIR testing.