Transportation of prion protein across the intestinal mucosa of scrapie-susceptible and scrapie-resistant sheep.
To determine the mechanisms of intestinal transport of infection, and early pathogenesis, of sheep scrapie, isolated gut-loops were inoculated to ensure that significant concentrations of scrapie agent would come into direct contact with the relevant ileal structures (epithelial, lymphoreticular, and nervous). Gut loops were inoculated with a scrapie brain pool homogenate or normal brain or sucrose solution. After surgery, animals were necropsied at time points ranging from 15 min to 1 month and at clinical end point. Inoculum-associated prion protein (PrP) was detected by immunohistochemistry in villous lacteals and in sub-mucosal lymphatics from 15 min to 3.5 h post-challenge. It was also detected in association with dendritic-like cells in the draining lymph nodes at up to 24 h post-challenge. Replication of infection, as demonstrated by the accumulation of disease-associated forms of PrP in Peyer's patches, was detected at 30 days and sheep developed clinical signs of scrapie at 18-22 months post-challenge. These results indicate discrepancies between the routes of transportation of PrP from the inoculum and sites of de novo-generated disease-associated PrP subsequent to scrapie agent replication. When samples of homogenized inoculum were incubated with alimentary tract fluids in vitro, only trace amounts of protease-resistant PrP could be detected by western blotting, suggesting that the majority of both normal and abnormal PrP within the inoculum is readily digested by alimentary fluids.
Jeffrey
M
M
Veterinary Laboratories Agency (VLA)-Lasswade, Pentlands Science Park, Midlothian, UK. m.jeffrey@vla.defra.gsi.gov.uk
González
L
L
Espenes
A
A
Press
C McL
CM
Martin
S
S
Chaplin
M
M
Davis
L
L
Landsverk
T
T
MacAldowie
C
C
Eaton
S
S
McGovern
G
G
D000818:Animals; D015153:Blotting, Western; D004063:Digestion; D005766:Gastrointestinal Contents; D020022:Genetic Predisposition to Disease; D005838:Genotype; D007082:Ileum / Q000382:microbiology; D007413:Intestinal Mucosa / Q000378:metabolism / Q000382:microbiology*; D008221:Lymphoid Tissue / Q000382:microbiology; D010581:Peyer's Patches / Q000382:microbiology; D011328:Prions / Q000302:isolation & purification / Q000472:pathogenicity / Q000493:pharmacokinetics*; D012608:Scrapie / Q000235:genetics / Q000382:microbiology*; D012756:Sheep; D014020:Tissue Extracts / Q000378:metabolism
D011328:Prions; D014020:Tissue Extracts