羊瘙痒因子263K经多种途径感染仓鼠的脑外组织PrP~(Sc)分子和沉积特点研究

目的　比较研究实验仓鼠经不同途径感染羊瘙痒病 (Scrapie)毒株 2 6 3K的终末期病鼠脑外组织内PrPSc分子和沉积特点。方法　以Scrapie 2 6 3K毒株经颅内、腹腔、心内、肌肉注射及灌胃等途径接种金黄地鼠 ,在终末期取脑、脊髓、脾、肾、舌、肌肉、小肠回盲部和胃组织 ,用HE染色观察病理变化 ,免疫组化法检测PrPSc的组织沉积特点 ,Westernblot检测PrPSc分子特征。结果　五种感染方式均可引起动物发病 ,在脑和脊髓组织中观察到典型的病理改变 ;PrPSc免疫组化检测显示外周途径感染动物脊髓白质内有大量沿纤维走行的PrPSc沉积 ,灰质前后角内围绕空泡点状或网状沉积 ,而颅内感染主要在中央管附近和后角出现大量的点状PrPSc沉积 ;脾脏、肾、小肠回盲部、胃组织中均观察到点状PrPSc的沉积 ;WesternBlot检测发现不同感染途径动物脊髓提取物均出现可抵抗蛋白酶消化的PrPSc条带 ,与脑提取物中PrPSc电泳性状完全一致 ;外周组织仅在脾脏检测到抵抗蛋白酶消化的PrPSc,但与正常对照比较 ,各种组织中PrP的总量明显增高 ,同时呈现与中枢神经组织不同的PrP电泳特征。结论　在TSE感染发病过程中 ,多种组织细胞成分可能参与了TSE感染因子的向中枢神经系统传递过程 ,PrP蛋白在中枢神经组织和其他外周组织细胞中的翻译后修饰及

Comperative study of the characteristics of PrPSc molecules and deposits in spinal cords and peripheral tissues of hamsters infected with scrapie strain 263K by different pathways

To understand the characteristics of PrP Sc molecules and deposits in spinal cords and other peripheral tissues in hamster infected with scrapie strain 263K in five challenge pathways.Golden hamsters were challenged through different pathways, including intracerebral (i.c.), intraperitoneal (i.p.), intragastrical (i.g.), intracardiac and intramuscular (i.m.)routes. At the terminal stage of clinical course, all animals were sacrificed and brain, spinal cord, spleen, ileocecum, kidney and stomach were dissected. The pathological changes, PrP Sc deposits, and patterns of PrP Sc were analyzed by HE stain, immunohistochemistry (IHC) assay and Western blotting. Typical TSE could be induced in the hamsters inoculated with strain 263K by all five pathways. The typical pathological changes were only found in brain tissues and spinal cords. PrP Sc specific immunohistochemistry assays revealed amounts of PrP Sc deposits along with the fibrils in white matters of spinal cords from the hamsters challenged through peripheral pathways, with dotted or reticular deposits surrounding the spongiform degenerations in anterior and posterior horn in gray matters. However, PrP Sc deposits were mainly observed in the regions of central tube and posterior horn in i.c. route. Sporadic dotted PrPSc deposits were also observed in the tissues of spleen, ileocecum, kidney and stomach. Protease resistant PrP Sc were detected in spinal cords with Western blotting, showing the same electrophoresis patterns as that of brain tissues. Among the tested peripheral tissues, only spleens contained detectable PrP Sc bands in Western blotting. However, the amounts of PrP proteins in the tested peripheral tissues were increased compared with the health control. Moreover, the electrophoresis patterns of PrP from peripheral tissues were distinct from that of central nerve tissues. In conclusion these data imply that several peripheral tissues and cells might take part in the transport of exotic PrP Sc to central nerve system during the pathogenesis of TSE. The post translation modification and metabolism processes of PrP protein in central nerve tissues as well as other peripheral tissues may be different.