医学微生物学课件--第32节 朊粒.ppt

医学微生物学 * Chapter 32 朊粒(Prion)仅有蛋白质, 无核酸多beta折叠, 对蛋白酶的抗性引起人库鲁病, 克-雅病 Cellular prion protein (PrPc) can be identical to scrapie like prion protein(PrPsc) in its protein sequence but differs in tertiary structure. PrPc PrionPsc Simplified model for prion disease. PrPsc, acts as a template. It associates with the helical form allowing the latter to be converted to the beta-pleated sheet resistant form There are now two molecules of the resistant form that can act as a template and so the process accelerates PrionPsc的抵抗力PrP抵抗力强，对甲醛，戊二醛，乙醇，蛋白酶, 标准高压灭菌法等具有抗性。可用以下方法灭菌:1N NaOH 1h, then 121 ℃ 1h1N NaOH 1h, then 134℃ 18min.  致病性 慢性, 退化性, 致死性中枢神经系统病患。临床上出现痴呆，共济失调，震颤等症状. 1. 瘙痒病（Scrapie）:皮肤瘙痒、摩擦，脱毛. 2. 疯牛病（Mad cow disease）:运动失调、狂躁 Parts of cattle at high risk for harboring the infectious agent for bovine spongiform encephalopathy (BSE), or mad cow disease, include the skull, brain, eyes, vertebral column, and spinal cord of cows at least 30 months of age. The tonsils and a portion of the small intestine of all cattle also may contain the agent. Federal agencies protect public health by prohibiting these cow parts in the human food supply.Infographic: FDA/Michael Ermarth 库鲁（Kuru）病Kuru(颤抖)病, 发生于巴布亚新几内亚宗教性食尸恶习，患者多为妇女，儿童。潜伏期4～30年，病人小脑受损，产生共济失调和震颤。一旦发病，一年内（6～9个月）内死亡. A child infected with Kuru 克雅病(Creutzfeldt-Jakob Disease,CJD)与克雅病新变种原因: Prion 自发突变, 常染色体显性遗传, 进食含PrPsc的牛肉, 医源性感染.潜伏期几～ 几十年，进行性发展的肌肉痉挛、痴呆、昏迷，发病后,多在12个月内死亡。病理：脑组织海绵状变性. *