Rapid diagnosis of influenza type A infection: comparison of shell-vial culture, directigen flu-A and enzyme-linked immunosorbent assay.
Two direct antigen detection methods (Directigen FLU A, Becton-Dickinson, Cokeysville, Md. and Influenza A virus ELISA Antigen detection kit, Alpha Biotech, Milano) were compared with isolation by shell-vial cultures for rapid diagnosis of influenza type A virus infection. The three methods were performed using a reference viral suspension consisting of a clinical isolate of influenza type A virus as well as 41 nasopharyngeal aspirates collected from patients with influenza symptoms. Influenza type A virus was recovered from 14 specimens by shell-vials. Ten specimens were positive by Directigen FLU A and 7 by ELISA antigen detection kit. When performed on clinical samples the sensitivity of Directigen FLU A and ELISA was 64.2% and 42.8%, respectively. The limit of sensitivity of the shell-vials, performed on a virus stock suspension titrated by haemagglutinin activity, was 0.06-0.03 HA units/ml at 24 hours or 72 hours after inoculation. Directigen FLU A and ELISA detected as positive a virus stock suspension containing 0.25 HA units/ml and 1 HA units/ml, respectively.
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Laboratorio Analisi chimico-cliniche e microbiologia, Ospedale Civile, Università di Padova.
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D000818:Animals; D000956:Antigens, Viral / Q000032:analysis*; D002460:Cell Line; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D007124:Immunoenzyme Techniques; D009980:Influenza A virus / Q000276:immunology / Q000302:isolation & purification*; D007251:Influenza, Human / Q000175:diagnosis* / Q000821:virology; D009305:Nasopharynx / Q000821:virology; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014776:Virus Cultivation
D000956:Antigens, Viral; D011933:Reagent Kits, Diagnostic