Dynamic characteristics of PrP~(Sc) deposits in the hamsters' brain tissues inoculated intracerebrally with scrapie 263K strain

Aim To observe the characteristics of PrP Sc deposits in the hamsters' brains infected with scrapie 263K. Methods After challenged intracerebrally with scrapie 263K,the animals were sacrificed 20 ,40 ,50 ,60 and 70 day postinoculation. PrP Sc deposits,neuropathological changes and protease resistant PrP were analyzed by immunohistochemistry (IHC),HE stain and Western blot. Results Few PrP Sc deposits were firstly identified in the brain tissues 20 day postinoculation. Intracellular deposits of PrP Sc were observed in the animals 40 day postinoculation,with more widely distribution. Larger granular,as well as plaque like PrP Sc were seen in the brain tissues 50 and 60 day postinoculation,with extensive spongiform degeneration in that of 70 day. Histoblot of PrP Sc deposited largely in the layer Ⅲ,Ⅳ and Ⅴ of cerebral cortex,pyramidal layer of hippocampus and granular layer of cerebellum,but not in white matter. Spongiform degeneration was firstly observed in cerebral cortex of the animals 40 day inoculation,and aggravated along with the incubation period. Protease resistant PrP Sc were firstly detected in brain homogenates prepared from the hamsters 40 day postinoculation. Total amount of PrP and the amount of PrP Sc in brain tissues increased significantly with prolong of incubation. Conclusion Along with the incubation,more extensive PrP Sc deposits distribute in the brain tissues of the infected hamsters with scrapie strain 263K. PrP Sc in central nerve tissues identified with IHC appears much earlier than the onset of clinical manifestations,even earlier than that with other commonly used methods.