Hamir A N, Kunkle R A, Richt J A, Miller J M, Greenlee J J
National Disease Center, ARS, USDA, Ames, IA 50010, USA.
Vet Pathol. 2008 Jan;45(1):7-11. 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 (PrP(Sc)) 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 PrP(Sc) in central nervous system and lymphoid tissues were present in these sheep. One intranasally inoculated sheep euthanized at 12 MPI had presence of PrP(Sc) 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.
羊瘙痒病是绵羊和山羊自然发生的一种致命性神经退行性疾病。本研究记录了用美国绵羊瘙痒病病原体接种的基因易感绵羊组织中的潜伏期、病理发现以及通过免疫组织化学检测到的异常朊病毒蛋白（PrP(Sc)）的分布情况。4月龄萨福克羔羊（密码子171处为QQ型）通过3种不同途径（鼻腔、腹腔和结膜）之一接种了由一组瘙痒病感染羊脑组成的接种物（编号为13 - 7）。除3只羊外，所有接种动物在接种后19至46个月（MPI）出现瘙痒病晚期临床症状时被安乐死。这些羊的大脑中出现海绵状病变，中枢神经系统和淋巴组织中存在PrP(Sc)标记。一只在12 MPI时经鼻腔接种后被安乐死的羊，其PrP(Sc)仅局限于咽扁桃体。这些结果表明，上呼吸道，特别是咽扁桃体，可能是朊病毒蛋白在瘙痒病感染环境中的进入门户。
