title: Oral challenge of brushtail possums (Trichosurus vulpecula) with possum enteroviruses: clinical observation, antibody response and virus excretion in faeces.
abstract: OBJECTIVE
  To investigate the pathogenesis of two cytopathic enteroviruses, W1 and W6, isolated from possums, to evaluate their potential as vectors for biological management of possums.
  
  
  METHODS
  Possums (n=10) were fed 1 x 107 median tissue culture infectious doses (TCID50) of either the W1 strain (Possums 1-5) or W6 strain (Possums 6-10), while controls (n=2, Possums 11 and 12) were fed uninfected cell culture medium. Blood samples were collected from all possums on Days -1, 2, 7, 14, 21 and 34 or 35 post-inoculation (p.i.), and bodyweight and rectal temperatures were measured on the same days. Virus specific antibodies were determined using virus neutralisation tests (VNTs). Faeces were collected on Days -1, 2, 7, 9, 14, 16, 21, 28 and 34 or 35 p.i., and the presence of W1 and W6 virus in faeces was determined using cell culture and reverse transcriptase-polymerase chain reaction (RT-PCR). Possums were euthanised on Day 34 or 35, and ileal Peyer's patches were collected for detection of virus using RT-PCR.
  
  
  RESULTS
  No diarrhoea or significant changes in rectal temperature or loss of bodyweight were observed in virus-inoculated possums during the study period. Virus-neutralising antibodies were detected using VNTs in 2/5 and 3/5 possums exposed to the W1 and W6 strain, respectively. Excretion of virus in faeces was detected in 6/10 virus-inoculated possums, from as early as Day 4 p.i.; virus excretion in faeces was transient in some and persistent in other possums up to the time of euthanasia. The viruses were detected in 3/10 virus-inoculated possums following necropsy, but were not detected using RT-PCR in sera collected on Days 2 and 7, nor in Peyer's patches of virus-inoculated possums collected on Day 34 or 35.
  
  
  CONCLUSIONS
  Possum enteroviruses W1 and W6 established an asymptomatic infection in the gastrointestinal tract (GIT) in a proportion of challenged possums. A virus-specific antibody response was elicited in infected possums, which excreted the virus in faeces for up to 35 days p.i. The absence of noticeable adverse effects in enterovirus-infected possums is an advantageous characteristic for candidate vectors on animal welfare grounds.
authors.affiliation: AgResearch, Wallaceville Animal Research Centre, PO Box 40-063, Upper Hutt, New Zealand. tao.zheng@agresearch.co.nz
authors.forename: T
authors.initials: T
authors.lastname: Zheng
authors.forename: H C M
authors.initials: HC
authors.lastname: Chiang
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D000917:Antibody Formation; D004770:Enterovirus / Q000276:immunology / Q000472:pathogenicity*; D004769:Enterovirus Infections / Q000276:immunology / Q000662:veterinary*; D005243:Feces / Q000821:virology; D005260:Female; D012367:RNA, Viral / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D048330:Trichosurus / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D012367:RNA, Viral