title: Evaluation of twenty-two rapid antigen detection tests in the diagnosis of Equine Influenza caused by viruses of H3N8 subtype.
abstract: BACKGROUND
  Equine influenza (EI) is a highly contagious disease caused by viruses of the H3N8 subtype. The rapid diagnosis of EI is essential to reduce the disease spread. Many rapid antigen detection (RAD) tests for diagnosing human influenza are available, but their ability to diagnose EI has not been systematically evaluated.
  
  
  OBJECTIVE
  The aim of this study was to compare the performance of 22 RAD tests in the diagnosis of EI.
  
  
  METHODS
  The 22 RAD tests were performed on fivefold serial dilutions of EI virus to determine their detection limits. The four most sensitive RAD tests (ImmunoAce Flu, BD Flu examan, Quick chaser Flu A, B and ESPLINE Influenza A&B-N) were further evaluated using nasopharyngeal samples collected from experimentally infected and naturally infected horses. The results were compared to those obtained using molecular tests.
  
  
  RESULTS
  The detection limits of the 22 RAD tests varied hugely. Even the four RAD tests showing the best sensitivity were 125-fold less sensitive than the molecular techniques. The duration of virus detection in the experimentally infected horses was shorter using the RAD tests than using the molecular techniques. The RAD tests detected between 27% and 73% of real-time RT-PCR-positive samples from naturally infected horses.
  
  
  CONCLUSIONS
  The study demonstrated the importance of choosing the right RAD tests as only three of 22 were fit for diagnosing EI. It was also indicated that even RAD tests with the highest sensitivity serve only as an adjunct to molecular tests because of the potential for false-negative results.
authors.affiliation: Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamanaka
authors.affiliation: Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Nemoto
authors.affiliation: Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Bannai
authors.affiliation: Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Tsujimura
authors.affiliation: Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kondo
authors.affiliation: Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan.
authors.forename: Tomio
authors.initials: T
authors.lastname: Matsumura
authors.affiliation: Virology Unit, Irish Equine Centre, Johnstown, Naas, Co. Kildare, Ireland.
authors.forename: Sarah
authors.initials: S
authors.lastname: Gildea
authors.affiliation: Virology Unit, Irish Equine Centre, Johnstown, Naas, Co. Kildare, Ireland.
authors.forename: Ann
authors.initials: A
authors.lastname: Cullinane
mesh_terms: D000818:Animals; D000914:Antibodies, Viral; D000956:Antigens, Viral / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D006734:Horse Diseases / Q000175:diagnosis* / Q000821:virology*; D006736:Horses; D006801:Humans; D053123:Influenza A Virus, H3N8 Subtype / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D007251:Influenza, Human / Q000175:diagnosis / Q000821:virology; D007564:Japan; D009305:Nasopharynx / Q000821:virology; D009976:Orthomyxoviridae Infections / Q000175:diagnosis / Q000662:veterinary* / Q000821:virology; D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic; D060888:Real-Time Polymerase Chain Reaction / Q000592:standards; D012680:Sensitivity and Specificity
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic
keywords: diagnosis; equine influenza; rapid antigen detection test