The evaluation of three diagnostic tests for the detection of equine influenza nucleoprotein in nasal swabs
Version of Record online: 7 FEB 2014
© 2014 The Authors. Influenza and Other Respiratory Viruses Published by John Wiley & Sons Ltd.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Influenza and Other Respiratory Viruses
Volume 8, Issue 3, pages 376–383, May 2014
How to Cite
2014) The evaluation of three diagnostic tests for the detection of equine influenza nucleoprotein in nasal swabs. Influenza and Other Respiratory Viruses 8(3), 376–383.et al. (
- Issue online: 10 APR 2014
- Version of Record online: 7 FEB 2014
- Manuscript Accepted: 27 DEC 2013
- Department of Agriculture, Food
- Marine under the National Development
- ELISA ;
- equine influenza;
- nucleoprotein Directigen;
- rapid antigen detection
Equine influenza (EI) is a highly contagious respiratory disease of horses.
The aim of this study was to evaluate two rapid antigen detection kits (Directigen or DFA, and Espline) and a commercial ELISA for the detection of EI nucleoprotein in nasal swabs.
Nasal swab samples from naturally and experimentally infected horses were used to compare the sensitivity and specificity of these assays to virus isolation (VI) and real-time RT-PCR.
If real-time RT-PCR was considered as the gold standard, the sensitivity of the other tests in field samples was 68% (DFA), 35% (ELISA), 29% (Espline), and 9% (VI). These tests had 100% specificity when compared to real-time RT-PCR. A receiver operating characteristic (ROC) curve indicated that decreasing the cutoff of the ELISA would increase sensitivity with some loss of specificity. In samples from experimentally infected horses, the sensitivity of the tests compared with real-time RT-PCR was 69% (VI), 27% (DFA), 6% (Espline), and 2% (ELISA). The specificity was 100% for Espline and ELISA and 95% for VI and DFA.
This study illustrated that DFA is the most sensitive antigen detection test evaluated for the diagnosis of EI and that it can detect virus in some subclinical infected and vaccinated horses. The results suggest that DFA is a useful adjunct to laboratory tests and may be effective as a screening test in a quarantine station or similar facility where horses are monitored daily.