title: Simultaneous detection and typing of influenza viruses A and B by a nested reverse transcription-PCR: comparison to virus isolation and antigen detection by immunofluorescence and optical immunoassay (FLU OIA).
abstract: A nested reverse transcription (RT)-PCR was developed for simultaneous detection and typing of influenza viruses A and B. The detection limit for influenza virus A subtypes H1 and H3 and that for influenza virus B were between 1 and 4 target gene copies per reaction for each type. The clinical benefit of the RT-PCR method was evaluated by comparing the results with virus isolation and direct immunofluorescence (IF) assays on 215 nasopharyngeal aspirates from patients with suspected influenza virus infection. The RT-PCR detected 83 cases of influenza A, compared to 66 cases detected by virus isolation and 68 cases detected by IF assay. The corresponding figures for the detection of influenza B were 15, 12, and 11 cases, respectively. In total, 16 out of 98 RT-PCR-positive specimens were negative by virus isolation and IF. An optical immunoassay for rapid detection of influenza A and B (FLU OIA; Bio Star Inc., Boulder, Colo.) was compared to RT-PCR and IF on 105 nasopharyngeal aspirates and 79 swabs. The sensitivity for the OIA was 40.4% compared to PCR and 48.8% compared to IF assay, when nasopharyngeal aspirates were examined. The specificities were 94.3 and 93.9%, respectively. The sensitivity was higher for OIA on nasopharyngeal swabs, 77.5% and 86.6% compared to PCR and IF, respectively, while the specificity was lower, 82.0% and 75.5%, respectively. The RT-PCR provides a sensitive and specific method for detecting and typing influenza viruses A and B. The rapid OIA is useful as a complementary test, but it cannot replace established methods without further evaluation.
authors.affiliation: Section of Virology, Department of Clinical Microbiology, University Hospital, S-751 85 Uppsala, Sweden. bjorn.herrmann@medsci.uu.se
authors.forename: B
authors.initials: B
authors.lastname: Herrmann
authors.forename: C
authors.initials: C
authors.lastname: Larsson
authors.forename: B W
authors.initials: BW
authors.lastname: Zweygberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000956:Antigens, Viral / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D007118:Immunoassay; D007223:Infant; D009980:Influenza A virus / Q000145:classification* / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D009981:Influenza B virus / Q000145:classification* / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D007251:Influenza, Human / Q000175:diagnosis / Q000821:virology*; D008875:Middle Aged; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity
chemical_list: D000956:Antigens, Viral