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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI:

    Performance characteristics of two real-time TaqMan polymerase chain reaction assays for the detection of WSSV in clinically diseased and apparently healthy prawns

    Nicholas J. G. Moody*, Peter G. Mohr, Lynette M. Williams, David M Cummins, John Hoad, Joanne Slater, Stacey T. Valdeter, Axel Colling, Nagendrakumar B. Singanallur, Ian A. Gardner, Nicholas Gudkovs, Mark St. J. Crane

    *Corresponding author:

    ABSTRACT: This study aimed to generate data on performance characteristics for 2 real-time TaqMan PCR assays (CSIRO and OIE WSSV qPCRs) for the purposes of (1) detection of white spot syndrome virus (WSSV) in clinically diseased prawns and (2) detection of WSSV in apparently healthy prawns. Analytical sensitivity of both assays was 2 to 20 genome copies per reaction, and analytical specificity was 100% after testing nucleic acid from 9 heterologous prawn pathogens and 4 prawn species. Results obtained after testing more than 20000 samples in up to 559 runs with the CSIRO WSSV qPCR and up to 293 runs with the OIE WSSV qPCR demonstrated satisfactory repeatability for both assays. Both assays demonstrated median diagnostic sensitivity (DSe) 100% (95% CI: 94.9–100%) when testing clinically diseased prawns. When 1591 test results from apparently healthy prawns were analysed by Bayesian latent class analysis, median DSe and diagnostic specificity (DSp) were 82.9% (95% PI: 75.0–90.2%) and 99.7% (95% PI: 98.6–99.99%) for the CSIRO WSSV qPCR and 76.8% (95% PI: 68.9–84.9%) and 99.7% (95% PI: 98.7–99.99%) for the OIE WSSV qPCR. When both assays were interpreted in parallel, median DSe increased to 98.3 (95% PI: 91.6–99.99%), and median DSp decreased slightly to 99.4% (95% PI: 97.9–99.99%). Routine testing of quantified positive controls by laboratories in the Australian laboratory network demonstrated satisfactory reproducibility of the CSIRO WSSV qPCR assay. Both assays demonstrated comparable performance characteristics, and the results contribute to the validation data required in the OIE validation pathway for the purposes of detection of WSSV in clinically diseased and apparently healthy prawns.