Experimental Transmission of US Scrapie Agent by Nasal, Peritoneal, and Conjunctival Routes to Genetically Susceptible Sheep

• Published in: Veterinary pathology 2008, Vol.45 (1), p.7-11
• Main Authors: Hamir, A.N, Kunkle, R.A, Richt, J.A, Miller, J.M, Greenlee, J.J
• Format: Article
• Language: English
• Subjects: Animals; Brain; Conjunctiva; disease transmission; Female; genetic predisposition; Genetic Predisposition to Disease; genetic susceptibility; genotype; histopathology; immunohistochemistry; incubation period; Injections; inoculation methods; inoculation routes; intraconjunctival inoculation; intranasal administration; intraperitoneal injection; Male; Nose; Peritoneum; Prions; PrPSc proteins; scrapie; Scrapie - genetics; Scrapie - transmission; Sheep; Suffolk (sheep breed); tissue distribution; United States
• ISSN: 0300-9858; 1544-2217
• DOI: 10.1354/vp.45-1-7

Scrapie is a naturally occurring fatal neurodegenerative disease of sheep and goats. This study documents incubation periods, pathologic findings, and distribution of abnormal prion proteins (PrPSc) by immunohistochemistry in tissues of genetically susceptible sheep inoculated with US sheep scrapie agent. Four-month-old Suffolk lambs (QQ at codon 171) were inoculated by 1 of 3 different routes (nasal, peritoneal, and conjunctival) with an inoculum (No. 13-7) consisting of a pool of scrapie-affected sheep brains. Except for 3 sheep, all inoculated animals were euthanized when advanced clinical signs of scrapie were observed between 19 and 46 months postinoculation (MPI). Spongiform lesions in the brains and labeling of PrPSc in central nervous system and lymphoid tissues were present in these sheep. One intranasally inoculated sheep euthanized at 12 MPI had presence of PrPSc that was confined to the pharyngeal tonsil. These results indicate that the upper respiratory tract, specifically the pharyngeal tonsil, may serve as a portal of entry for prion protein in scrapie-infected environments.