title: Natural exposure of horses to mosquito-borne flaviviruses in south-east Queensland, Australia.
abstract: In 2011 an unprecedented epidemic of equine encephalitis occurred in south-eastern (SE) Australia following heavy rainfall and severe flooding in the preceding 2-4 months. Less than 6% of the documented cases occurred in Queensland, prompting the question of pre-existing immunity in Queensland horses. A small-scale serological survey was conducted on horses residing in one of the severely flood-affected areas of SE-Queensland. Using a flavivirus-specific blocking-ELISA we found that 63% (39/62) of horses older than 3 years were positive for flavivirus antibodies, and of these 18% (7/38) had neutralizing antibodies to Murray Valley encephalitis virus (MVEV), Kunjin virus (WNV(KUN)) and/or Alfuy virus (ALFV). The remainder had serum-neutralizing antibodies to viruses in the Kokobera virus (KOKV) complex or antibodies to unknown/untested flaviviruses. Amongst eight yearlings one presented with clinical MVEV-encephalomyelitis, while another, clinically normal, had MVEV-neutralizing antibodies. The remaining six yearlings were flavivirus antibody negative. Of 19 foals born between August and November 2011 all were flavivirus antibody negative in January 2012. This suggests that horses in the area acquire over time active immunity to a range of flaviviruses. Nevertheless, the relatively infrequent seropositivity to MVEV, WNV(KUN) and ALFV (15%) suggests that factors other than pre-existing immunity may have contributed to the low incidence of arboviral disease in SE-Queensland horses during the 2011 epidemic.
authors.affiliation: Australian Infectious Diseases Research Centre, University of Queensland, St. Lucia, QLD 4078, Australia. h.bielefeldtohmann1@uq.edu.au.
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Prow
authors.forename: Cindy S E
authors.initials: CS
authors.lastname: Tan
authors.forename: Wenqi
authors.initials: W
authors.lastname: Wang
authors.forename: Jody
authors.initials: J
authors.lastname: Hobson-Peters
authors.forename: Lisa
authors.initials: L
authors.lastname: Kidd
authors.forename: Anita
authors.initials: A
authors.lastname: Barton
authors.forename: John
authors.initials: J
authors.lastname: Wright
authors.forename: Roy A
authors.initials: RA
authors.lastname: Hall
authors.forename: Helle
authors.initials: H
authors.lastname: Bielefeldt-Ohmann
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D005260:Female; D005416:Flavivirus / Q000276:immunology*; D018177:Flavivirus Infections / Q000453:epidemiology / Q000276:immunology* / Q000662:veterinary; D006734:Horse Diseases / Q000453:epidemiology / Q000276:immunology*; D006736:Horses / Q000276:immunology; D011793:Queensland / Q000453:epidemiology; D016036:Seroepidemiologic Studies
chemical_list: D000914:Antibodies, Viral
references.citation: Curr Top Microbiol Immunol. 2002;267:253-69
references.pmid: 12082993
references.citation: J Clin Microbiol. 2003 Jun;41(6):2676-9
references.pmid: 12791902
references.citation: Med J Aust. 1996 Sep 2;165(5):256-60
references.pmid: 8816682
references.citation: Emerg Infect Dis. 2012 May;18(5):792-800
references.pmid: 22516173
references.citation: J Virol Methods. 1995 Feb;51(2-3):201-10
references.pmid: 7738140
references.citation: Am J Trop Med Hyg. 1982 May;31(3 Pt 1):548-55
references.pmid: 6177259
references.citation: Curr Microbiol. 2009 Dec;59(6):579-83
references.pmid: 19784699
references.citation: Microbes Infect. 2001 Mar;3(3):223-9
references.pmid: 11358716
references.citation: J Vet Med Sci. 2009 Jul;71(7):969-74
references.pmid: 19652487
references.citation: J Med Entomol. 1999 Nov;36(6):861-8
references.pmid: 10593092
references.citation: Aust Vet J. 2003 Jan-Feb;81(1-2):56-7
references.pmid: 15084012
references.citation: Emerg Infect Dis. 2013 Apr;19(4):635-7
references.pmid: 23631894
references.citation: Pathology. 1998 Aug;30(3):286-8
references.pmid: 9770194
references.citation: J Med Entomol. 2000 Mar;37(2):250-8
references.pmid: 10730496
references.citation: Evol Bioinform Online. 2010 Jun 15;6:91-6
references.pmid: 20938485
references.citation: J Vet Diagn Invest. 2012 Mar;24(2):431-6
references.pmid: 22379060
references.citation: Vet Microbiol. 2008 Jun 22;129(3-4):378-83
references.pmid: 18182255
references.citation: J Gen Virol. 2005 Jan;86(Pt 1):121-124
references.pmid: 15604438
references.citation: J Gen Virol. 2013 Jul;94(Pt 7):1462-1467
references.pmid: 23426358
references.citation: Med J Aust. 1999 Jun 7;170(11):533-6
references.pmid: 10397044
references.citation: Am J Trop Med Hyg. 2008 Jan;78(1):45-52
references.pmid: 18187784
references.citation: J Gen Virol. 2010 Jun;91(Pt 6):1407-17
references.pmid: 20130134
references.citation: J Gen Virol. 2008 Dec;89(Pt 12):3063-3072
references.pmid: 19008394
references.citation: Aust Vet J. 2013 Jan-Feb;91(1-2):5-13
references.pmid: 23356366
references.citation: Vector Borne Zoonotic Dis. 2008 Dec;8(6):805-11
references.pmid: 18973445
references.citation: J Vector Ecol. 1998 Jun;23(1):1-46
references.pmid: 9673928
references.citation: Emerg Infect Dis. 2007 Nov;13(11):1788-90
references.pmid: 18217573
references.citation: Aust J Exp Biol Med Sci. 1964 Apr;42:149-64
references.pmid: 14150749
references.citation: Vector Borne Zoonotic Dis. 2011 Apr;11(4):447-50
references.pmid: 20575642
references.citation: Bull World Health Organ. 1981;59(6):895-900
references.pmid: 6978196
references.citation: Virus Res. 2000 Jun;68(1):7-13
references.pmid: 10930658
references.citation: Am J Trop Med Hyg. 2006 Jul;75(1):21-5
references.pmid: 16837702
references.citation: Vaccine. 2006 Jan 23;24(4):516-24
references.pmid: 16129523