title: Exposure of sheep scrapie brain homogenate to rumen-simulating conditions does not result in a reduction of PrP(Sc) levels.
abstract: OBJECTIVE
  Experiments were designed to evaluate the potential of rumen-simulating conditions to reduce PrP(Sc) levels.
  
  
  RESULTS
  Scrapie-positive brain material was incubated under rumen-simulating conditions. Time points were taken over a 24-h period and PrP(Sc) levels were analysed by Western blot. No loss of PrP(Sc) was observed over a 24-h time period.
  
  
  CONCLUSIONS
  Our results indicate that a fully developed rumen fermentation does not provide significant protection against prion infection via the oral route. Developmental changes including senescence of immune system function or other developmental changes in the gastrointestinal tract are potential mechanisms by which relative bovine spongiform encephalopathy (BSE) susceptibility might vary with age.
  
  
  CONCLUSIONS
  Epidemiology of the BSE outbreak in the United Kingdom indicates that younger animals were at higher risk of infection. The rumen undergoes pronounced developmental changes early in life, coinciding with the introduction of fibre into the diet. The timeframe of highest risk of infection overlaps the time in life prior to full rumen development. This work indicates that a fully developed rumen does not provide significant protection against prion infection via the oral route of infection. This result implicates other developmental changes that are responsible for the age-dependent susceptibility of cattle to BSE.
authors.affiliation: Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA 50010, USA. enicholson@nadc.ars.usda.gov
authors.forename: E M
authors.initials: EM
authors.lastname: Nicholson
authors.forename: J A
authors.initials: JA
authors.lastname: Richt
authors.forename: M A
authors.initials: MA
authors.lastname: Rasmussen
authors.forename: A N
authors.initials: AN
authors.lastname: Hamir
authors.forename: S
authors.initials: S
authors.lastname: Lebepe-Mazur
authors.forename: R L
authors.initials: RL
authors.lastname: Horst
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001923:Brain Chemistry; D002417:Cattle; D002457:Cell Extracts / Q000737:chemistry; D018620:PrPSc Proteins / Q000032:analysis* / Q000378:metabolism; D012417:Rumen / Q000737:chemistry* / Q000382:microbiology*; D012608:Scrapie / Q000276:immunology*; D034561:Sheep, Domestic
chemical_list: D002457:Cell Extracts; D018620:PrPSc Proteins