title: Comparison of assays for the detection of West Nile virus antibodies in equine serum after natural infection or vaccination.
abstract: West Nile virus (WNV) mainly infects birds, horses and humans. Outcomes of the infection range from mild uncharacteristic signs to fatal neurologic disease. The main objectives of the present study were to measure serum IgG and IgM antibodies in naturally exposed and vaccinated horses and to compare results of haemagglutination inhibition test (HIT), enzyme-linked immunosorbent assay (ELISA) and plaque reduction neutralisation test (PRNT). Altogether 224 animals were tested by HIT for WNV antibodies and 41 horses were simultaneously examined by ELISA and PRNT. After primary screening for WNV antibodies, horses were vaccinated. Samples were taken immediately before and 3-5 weeks after each vaccination. McNemar's chi-squared and percent agreement tests were used to detect concordance between HIT, ELISA and PRNT. Analyses by HIT confirmed the presence of WNV antibodies in 27/105 (26%) naturally exposed horses. Sera from 57/66 (86%) vaccinated animals were positive before the first booster and from 11/11 (100%) before the second booster. HIT was less sensitive for detecting IgG antibodies. We could detect postvaccination IgM in 13 cases with IgM antibody capture ELISA (MAC-ELISA) and in 7 cases with HIT. WNV is endemic in Hungary and regularly causes natural infections. Protective antibodies could not be measured in some of the cases 12 months after primary vaccinations; protection is more reliable after the first yearly booster. Based on our findings it was not possible to differentiate infected from recently vaccinated horses using MAC-ELISA. HIT cannot be used as a substitute for ELISA or PRNT when detecting IgG, but it proved to be a useful tool in this study to gain statistical information about the tendencies within a fixed population of horses.
authors.affiliation: MTA-SZIE Large Animal Clinical Research Group, Dóra major, Üllő, 2225, Hungary; Kaposvár University, Doctoral School of Animal Science, Guba Sándor u. 40., Kaposvár, 7400, Hungary. Electronic address: joo.kinga@aotk.szie.hu.
authors.forename: Kinga
authors.initials: K
authors.lastname: Joó
authors.affiliation: University of Veterinary Medicine, Department of Microbiology and Infectious Diseases, Hungária krt. 23-25., Budapest, 1143, Hungary; Viral Zoonoses, Emerging and Vector-Borne Infections Group, Institute of Virology, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria. Electronic address: bakonyi.tamas@aotk.szie.hu.
authors.forename: Tamás
authors.initials: T
authors.lastname: Bakonyi
authors.affiliation: MTA-SZIE Large Animal Clinical Research Group, Dóra major, Üllő, 2225, Hungary. Electronic address: szenci.otto@aotk.szie.hu.
authors.forename: Ottó
authors.initials: O
authors.lastname: Szenci
authors.affiliation: Vet Agro Sup, Universite de Lyon, Cliniques Vétérinaires, Lyon, France. Electronic address: sardi.sara@gmail.com.
authors.forename: Sára
authors.initials: S
authors.lastname: Sárdi
authors.affiliation: National Center for Epidemiology, National Reference Laboratory for Viral Zoonoses, Albert Flórián út 2-6, Budapest, 1097, Hungary. Electronic address: ferenczi.emoke@oek.antsz.hu.
authors.forename: Emőke
authors.initials: E
authors.lastname: Ferenczi
authors.affiliation: University of Veterinary Medicine, Department of Microbiology and Infectious Diseases, Hungária krt. 23-25., Budapest, 1143, Hungary. Electronic address: monika.barna@aotk.szie.hu.
authors.forename: Mónika
authors.initials: M
authors.lastname: Barna
authors.affiliation: National Food Chain Safety Office, Veterinary Diagnostic Directorate, Tábornok u. 2., 1143, Budapest, Hungary. Electronic address: malik.peter@aotk.szie.hu.
authors.forename: Péter
authors.initials: P
authors.lastname: Malik
authors.affiliation: Institute of Vertebrate Biology, Academy of Sciences, Kvetna 8, 60365, Brno, Czechia. Electronic address: zhubalek@brno.cas.cz.
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Hubalek
authors.affiliation: MTA-SZIE Large Animal Clinical Research Group, Dóra major, Üllő, 2225, Hungary. Electronic address: ezustezust@gmail.com.
authors.forename: Orsolya
authors.initials: O
authors.lastname: Fehér
authors.affiliation: MTA-SZIE Large Animal Clinical Research Group, Dóra major, Üllő, 2225, Hungary; University of Veterinary Medicine, Institute for Animal Breeding, Nutrition and Laboratory Animal Science, István utca 2, 1078, Budapest, Hungary. Electronic address: kutasi.orsolya@aotk.szie.hu.
authors.forename: Orsolya
authors.initials: O
authors.lastname: Kutasi
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary*; D006385:Hemagglutination Inhibition Tests / Q000662:veterinary*; D006734:Horse Diseases / Q000097:blood / Q000276:immunology / Q000821:virology*; D006736:Horses; D014765:Viral Vaccines / Q000276:immunology*; D014901:West Nile Fever / Q000276:immunology / Q000662:veterinary*; D014902:West Nile virus
chemical_list: D000914:Antibodies, Viral; D014765:Viral Vaccines
keywords: Enzymelinked immunosorbent assay; Haemagglutination-inhibition test; Natural infection; Plaque reduction neutralization test; Vaccination; West Nile virus