title: The evaluation of three diagnostic tests for the detection of equine influenza nucleoprotein in nasal swabs.
abstract: BACKGROUND
  Equine influenza (EI) is a highly contagious respiratory disease of horses.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors: Virology Unit, The Irish Equine Centre, Johnstown, Naas, Co. Kildare, Ireland.
authors: Pamela
authors: P
authors: Galvin
authors: Sarah
authors: S
authors: Gildea
authors: Maura
authors: M
authors: Nelly
authors: Michelle
authors: M
authors: Quinlivan
authors: Sean
authors: S
authors: Arkins
authors: Cathal
authors: C
authors: Walsh
authors: Ann
authors: A
authors: Cullinane
mesh_terms: D000818:Animals; D003955:Diagnostic Tests, Routine / Q000295:instrumentation / Q000379:methods* / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation / Q000379:methods / Q000662:veterinary; D006734:Horse Diseases / Q000175:diagnosis*; D006736:Horses; D009666:Nose / Q000821:virology*; D019590:Nucleocapsid Proteins; D009976:Orthomyxoviridae Infections / Q000175:diagnosis / Q000662:veterinary*; D016601:RNA-Binding Proteins / Q000032:analysis* / Q000235:genetics; D011933:Reagent Kits, Diagnostic / Q000662:veterinary; D012680:Sensitivity and Specificity; D014758:Viral Core Proteins / Q000032:analysis* / Q000235:genetics
chemical_list: C048842:NP protein, Influenza A virus; D019590:Nucleocapsid Proteins; D016601:RNA-Binding Proteins; D011933:Reagent Kits, Diagnostic; D014758:Viral Core Proteins
keywords: Diagnosis; ELISA; Espline; equine influenza; nucleoprotein Directigen; rapid antigen detection