title: Koala retrovirus genotyping analyses reveal a low prevalence of KoRV-A in Victorian koalas and an association with clinical disease.
abstract: OBJECTIVE
  Koala retrovirus (KoRV) is undergoing endogenization into the genome of koalas in Australia, providing an opportunity to assess the effect of retrovirus infection on the health of a population. The prevalence of KoRV in north-eastern Australia (Queensland and New South Wales) is 100 %, whereas previous preliminary investigations in south-eastern Australia (Victoria) suggested KoRV is present at a lower prevalence, although the values have varied widely. Here, we describe a large study of free-ranging koalas in Victoria to estimate the prevalence of KoRV and assess the clinical significance of KoRV infection in wild koalas.
  
  
  METHODS
  Blood or spleen samples from 648 koalas where tested for KoRV provirus, and subsequently genotyped, using PCRs to detect the pol and env genes respectively. Clinical data was also recorded where possible and analysed in comparison to infection status.
  
  
  RESULTS
  The prevalence of KoRV was 24.7 % (160/648). KoRV-A was detected in 141/160 cases, but KoRV-B, a genotype associated with neoplasia in captive koalas, was not detected. The genotype in 19 cases could not be determined. Genomic differences between KoRV in Victoria and type strains may have impacted genotyping. Factors associated with KoRV infection, based on multivariable analysis, were low body condition score, region sampled, and 'wet bottom' (a staining of the fur around the rump associated with chronic urinary incontinence). Koalas with wet bottom were nearly twice as likely to have KoRV provirus detected than those without wet bottom (odds ratio=1.90, 95 % confidence interval 1.21, 2.98).
  
  
  CONCLUSIONS
  Our findings have important implications for the conservation of this iconic species, particularly regarding translocation potential of Victorian koalas.
authors.affiliation: Asia Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Alistair R
authors.initials: AR
authors.lastname: Legione
authors.affiliation: Veterinary Department, Melbourne Zoo, Parkville, Victoria, Australia.|Asia Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Jade L S
authors.initials: JLS
authors.lastname: Patterson
authors.affiliation: Wildlife Health Surveillance Victoria, The University of Melbourne, Werribee, Victoria, Australia.|Asia Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Pam
authors.initials: P
authors.lastname: Whiteley
authors.affiliation: Asia Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Firestone
authors.affiliation: Australian Wildlife Health Centre, Healesville Sanctuary, Healesville, Victoria, Australia.|Asia Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Megan
authors.initials: M
authors.lastname: Curnick
authors.affiliation: Veterinary Department, Melbourne Zoo, Parkville, Victoria, Australia.
authors.forename: Kate
authors.initials: K
authors.lastname: Bodley
authors.affiliation: Veterinary Department, Melbourne Zoo, Parkville, Victoria, Australia.|Asia Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Lynch
authors.affiliation: Centre for Equine Infectious Diseases, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: James R
authors.initials: JR
authors.lastname: Gilkerson
authors.affiliation: Asia Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Fiona M
authors.initials: FM
authors.lastname: Sansom
authors.affiliation: Asia Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Devlin
mesh_terms: D000818:Animals; D004279:DNA, Viral / Q000235:genetics; D005838:Genotype; D060005:Genotyping Techniques; D016015:Logistic Models; D015999:Multivariate Analysis; D009517:New South Wales / Q000453:epidemiology; D048368:Phascolarctidae / Q000821:virology*; D015995:Prevalence; D011793:Queensland / Q000453:epidemiology; D012190:Retroviridae / Q000235:genetics / Q000302:isolation & purification*; D012192:Retroviridae Infections / Q000453:epidemiology / Q000662:veterinary*
chemical_list: D004279:DNA, Viral