title: Virulence and Evolution of West Nile Virus, Australia, 1960-2012.
abstract: Worldwide, West Nile virus (WNV) causes encephalitis in humans, horses, and birds. The Kunjin strain of WNV (WNVKUN) is endemic to northern Australia, but infections are usually asymptomatic. In 2011, an unprecedented outbreak of equine encephalitis occurred in southeastern Australia; most of the ≈900 reported cases were attributed to a newly emerged WNVKUN strain. To investigate the origins of this virus, we performed genetic analysis and in vitro and in vivo studies of 13 WNVKUN isolates collected from different regions of Australia during 1960-2012. Although no disease was recorded for 1984, 2000, or 2012, isolates collected during those years (from Victoria, Queensland, and New South Wales, respectively) exhibited levels of virulence in mice similar to that of the 2011 outbreak strain. Thus, virulent strains of WNVKUN have circulated in Australia for >30 years, and the first extensive outbreak of equine disease in Australia probably resulted from a combination of specific ecologic and epidemiologic conditions.
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Prow
authors.forename: Judith H
authors.initials: JH
authors.lastname: Edmonds
authors.forename: David T
authors.initials: DT
authors.lastname: Williams
authors.forename: Yin X
authors.initials: YX
authors.lastname: Setoh
authors.forename: Helle
authors.initials: H
authors.lastname: Bielefeldt-Ohmann
authors.forename: Willy W
authors.initials: WW
authors.lastname: Suen
authors.forename: Jody
authors.initials: J
authors.lastname: Hobson-Peters
authors.forename: Andrew F
authors.initials: AF
authors.lastname: van den Hurk
authors.forename: Alyssa T
authors.initials: AT
authors.lastname: Pyke
authors.forename: Sonja
authors.initials: S
authors.lastname: Hall-Mendelin
authors.forename: Judith A
authors.initials: JA
authors.lastname: Northill
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Johansen
authors.forename: David
authors.initials: D
authors.lastname: Warrilow
authors.forename: Jianning
authors.initials: J
authors.lastname: Wang
authors.forename: Peter D
authors.initials: PD
authors.lastname: Kirkland
authors.forename: Stephen
authors.initials: S
authors.lastname: Doggett
authors.forename: Christy C
authors.initials: CC
authors.lastname: Andrade
authors.forename: Aaron C
authors.initials: AC
authors.lastname: Brault
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Khromykh
authors.forename: Roy A
authors.initials: RA
authors.lastname: Hall
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D000956:Antigens, Viral / Q000235:genetics; D001315:Australia / Q000453:epidemiology; D002460:Cell Line; D019143:Evolution, Molecular; D016679:Genome, Viral; D006801:Humans; D051379:Mice; D014774:Virulence; D014901:West Nile Fever / Q000453:epidemiology / Q000821:virology*; D014902:West Nile virus / Q000235:genetics* / Q000472:pathogenicity*
chemical_list: D000911:Antibodies, Monoclonal; D000956:Antigens, Viral
keywords: Australia; West Nile virus; encephalitis; evolutionary markers; flavivirus; vector-borne infections; virulence; viruses; zoonoses