Comparison of commercial influenza A virus assays in detecting avian influenza H7N9 among poultry cloacal swabs, China.
BACKGROUND: Avian H7N9 virus emerged in China in February 2013 and has since spread widely among China's poultry, causing numerous human infections. OBJECTIVES: To compare World Health Organization (WHO) and US commercial influenza assays in detecting avian H7N9 virus in poultry cloacal specimens. STUDY DESIGN: Between April 6 and July 15, 2013, 261 cloacal swabs were collected from commercial poultry in Nanjing and Wuxi City, Jiangsu Province, China. Swabs were screened with the WHO's influenza A and H7N9 real-time RT-PCR (qRT-PCR) assays. A blinded panel of 97 specimens (27 H7N9-positive and 70 influenza A-negative) was then used to compare 3 antigen based commercial assays (Remel Xpect Flu A&B, Quidel Quickvue influenza, and Quidel Sofia Influenza A+B), and 2 molecular commercial assays (Quidel Molecular Influenza A+B assay and Life Technologies VetMAX™-Gold SIV Detection Kit). None of these commercial assays were approved for use with poultry specimens. RESULTS: Considering the WHO H7N9 qRT-PCR assay as the gold standard, all assays except the Quidel Quickvue influenza assay had high specificity (ranging from 96 to 99%). Regarding sensitivity, the Life Technologies VetMAX™-Gold SIV Detection Kit (100%; 95% CI 87-100%) and the Quidel Molecular Influenza A+B assay (85%; 95% CI 66-96%) performed the best. The sensitivities of the non-molecular antigen detection assays were either unable to detect small amounts of H7N9 viral RNA or were inhibited by specimen type. CONCLUSIONS: The Life Technologies VetMAX™-Gold SIV Detection Kit and the Quidel Molecular Influenza A+B assay are comparable in performance to the WHO H7N9 qRT-PCR assay in detecting H7N9 from poultry cloacal specimens.
Ma, M-J; Yang, X-X; Xia, X; Anderson, BD; Heil, GL; Qian, Y-H; Lu, B; Cao, W-C; Gray, GC
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