title: Involvement of gut-associated lymphoid tissue of ruminants in the spread of transmissible spongiform encephalopathies.
abstract: Scrapie is a transmissible spongiform encephalopathy (TSE) and its spread across the intestine of sheep is linked to the biology of intestinal Peyer's patches (PPs). Specialized epithelial cells, M cells, would appear to be the portal of entry for the scrapie agent, PrP(Sc), while lymphoid nodules of PPs become major sites of accumulation of PrP(Sc) as the infection becomes established. Furthermore, evidence suggests that the enteric nervous system supplying the PPs is important for neuroinvasion. The gut-associated lymphoid tissue (GALT) of ruminants shows morphological and functional differences to the GALT of mice and humans. Recent investigations of aging scrapie-affected sheep revealed a substantial network of nerve fibres in the lymphoid nodules of PPs, contradicting the widely held notion that lymphoid nodules are poorly innervated. Advances in the understanding of the pathogenesis of scrapie may be achieved by a deeper appreciation of the development, morphology and function of GALT in small ruminants.
authors.affiliation: Department of Morphology, Genetics and Aquatic Biology, Norwegian School of Veterinary Science, P.O. Box 8146 Dep., Oslo, Norway. charles.press@veths.no
authors.forename: Charles McL
authors.initials: CM
authors.lastname: Press
authors.forename: Ragna
authors.initials: R
authors.lastname: Heggebø
authors.forename: Arild
authors.initials: A
authors.lastname: Espenes
mesh_terms: D000818:Animals; D006801:Humans; D007413:Intestinal Mucosa / Q000276:immunology* / Q000473:pathology* / Q000821:virology; D008221:Lymphoid Tissue / Q000276:immunology* / Q000473:pathology* / Q000821:virology; D017096:Prion Diseases / Q000276:immunology* / Q000473:pathology / Q000635:transmission*; D012418:Ruminants