Rapid diagnosis of equine influenza by the Directigen FLU-A enzyme immunoassay
Chambers, T.M.; Shortridge, K.F.; Li, P.H.; Powell, D.G.; Watkins, K.L.
Veterinary Record 135(12): 275-279
1994
ISSN/ISBN: 0042-4900 PMID: 7817505 Document Number: 425700
The Directigen FLU-A enzyme immunoassay was tested for its ability to detect equine-2 influenza viruses in nasopharyngeal fluids from horses and ponies. 125 swabs from experimental infections and from different sources of natural infection in the USA and Hong Kong were examined. The assay results were compared with the results of standard virus culture in embryonated chicken eggs or Madin-Darby canine kidney cells, and with the serology of the horses sampled. In comparison with virus culture the enzyme immunoassay showed 83% sensitivity, 78% specificity, 70% positive predictive value and 88% negative predictive value. The test appeared to be more sensitive than haemagglutination for the detection of low levels of virus in embryonated egg cultures. It also detected equine-1 influenza virus in culture. The test is rapid (15 minutes), simple, and should be a convenient method for the rapid diagnosis and screening of horses for equine influenzavirus infection.