羊瘙痒因子263K毒株感染金黄地鼠后鼠脑组织中检出PrP-res蛋白及其神经病理学研究

羊瘙痒病是累及山羊及绵羊的可传播海绵状脑病。为了观察羊瘙痒因子 (Scrapie)的病原特征及病理组织改变特点 ,将羊瘙痒因子 2 6 3K毒株颅内接种至金黄地鼠。经过 81～ 110天的潜伏期 ,89%的动物发病 (17/19只 )。对发病地鼠的神经病理学检测发现 ,海绵状空泡变性的检出率为 5 9% ,淀粉样斑的检出率为 17 6 %。利用免疫组化和蛋白酶消化后的Westernblotting检测证实 ,10 0 %的发病地鼠的脑组织中都出现蛋白酶抗性朊蛋白 (PrP res)。17只发病地鼠脑组织提取物中 ,PrP res的泳动位置和分子量大小完全一致 ,出现两条分子量在 2 5kD～ 31kD的反应带。尝试应用快速玻片印迹法检测病变组织中的PrP res,结果显示 ,与常规固定包埋切片的免疫组化检出效果相似。这提示脑组织印片法可成为临床检测克 雅氏病 (Creutzfeldt Jacobdisease ,CJD)患者脑组织活检标本中PrP res的快速、有效的方法。羊瘙痒因子 2 6 3K成功感染金黄地鼠再次证明 ,金黄地鼠是TSE感染因子良好的动物模型 ,发病率高 ,潜伏期短 ,发病动物PrP res的检出率明显高于典型病理改变的检出率。新生成的PrP res的电泳类型与接种的TSE因子有关 ,与宿主的个体差异无关 ,提示TSE感染因子的确存在“株”的现象。

PrP-res Protein and Neuropathological Analyses of the Brain Tissues from Hamsters Infected with Scrapie 263K

Scrapie is a kind of transmissible spongiformencephalopathies(TSE)involving in sheep and goat. To study the characteristics of the infectious agent and the neuropathology, Scrapies agent 263K was inoculated into the brains of the hamsters. 81 to 110 days after inoculation, 89% animals(17/19)appeared typical symptoms of TSE. Neuropathological studies revealed that 59% infected hamsters showed spongiform degeneration and 17% showed amyloid plaques. By immunohistochemistry and proteinase K-digested Western blot, the proteinase-resistant PrP-res proteins were detected in the brain tissues from all the infected animals. The electrophoresis patterns and the evaluated molecular weights of the PrP-res proteins from 17 infected hamsters were all the same, presenting two bands between roughly 25 kD and 31 kD in Western blot assays. Moreover, imprints of fresh brain tissues on slides were tested for PrP-res proteins. It showed similar results as that of routinely used paraffin-embedded slides by immunohistochemistry assays, which implies that this technique might be an effective method to detect PrP-res in the brain biopsies of the patients with CJD. Successful infection of Scrapie agent 263K in hamsters confirmed that baby hamster is an ideal model for TSE agents, with shorter incubation period and higher morbidity. The detecting rate of PrP-res is clearly higher than that of the neuropathological changes in the brain tissues from the infected animals. The electrophoresis patterns of the newly formed PrP-res proteins depend on the inoculated TSE agents, but not the individual animals, suggesting that there might be various “strains" among TSE agents.