title: Role of palatine tonsils as a prion entry site in classical and atypical experimental sheep scrapie.
abstract: Atypical and classical scrapie-infected sheep brain tissue was monolaterally injected into the tonsils of lambs to investigate their role as a prion entry point. We first detected classical PrP(Sc) within the inoculated tonsil and in the ipsilateral retropharyngeal lymph node at 3 months postinoculation (p.i.). At 7 months p.i., PrP(Sc) colonized other lymphoid tissues bilaterally, including ileal Peyer's patches. The earliest PrP(Sc) deposition within the brain was ipsilaterally observed at 9 months p.i. in the substantia reticularis of the medulla oblongata. At 12 months p.i., PrP(Sc) deposition was present bilaterally in the nucleus parasympathicus nervi vagi, as well as in the intermediolateral cell column of the thoracolumbar spinal cord. No PrP(Sc) was detected in the lambs inoculated with atypical scrapie. These findings suggest that neuroinvasion may naturally occur from the tonsil after a widespread prion replication within the lymphoid tissues during classical scrapie only, thus mimicking the pathogenesis after oral ingestion.
authors.affiliation: Istituto Zooprofilattico Sperimentale of Sardinia, Sassari, Italy.
authors.forename: Maria G
authors.initials: MG
authors.lastname: Cancedda
authors.forename: Giovanni
authors.initials: G
authors.lastname: Di Guardo
authors.forename: Roberto
authors.initials: R
authors.lastname: Chiocchetti
authors.forename: Francesca
authors.initials: F
authors.lastname: Demontis
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Marruchella
authors.forename: Caterina
authors.initials: C
authors.lastname: Sorteni
authors.forename: Caterina
authors.initials: C
authors.lastname: Maestrale
authors.forename: Alfio
authors.initials: A
authors.lastname: Lai
authors.forename: Ciriaco
authors.initials: C
authors.lastname: Ligios
mesh_terms: D000818:Animals; D008221:Lymphoid Tissue / Q000378:metabolism / Q000473:pathology; D014066:Palatine Tonsil / Q000378:metabolism* / Q000473:pathology; D010581:Peyer's Patches / Q000378:metabolism / Q000473:pathology; D018620:PrPSc Proteins / Q000378:metabolism*; D012608:Scrapie / Q000378:metabolism* / Q000473:pathology; D012756:Sheep
chemical_list: D018620:PrPSc Proteins