羊瘙痒因子263K经颅内注射感染仓鼠后半数致死量(LD_(50))的测定

目的测定羊瘙痒因子263K经颅内注射感染仓鼠后的LD50。方法将感染羊瘙痒因子263K的仓鼠脑组织用生理盐水制成10%(w/v)脑组织匀浆,梯度稀释后感染仓鼠,观察仓鼠的发病情况。以Reed-Muench公式计算LD50,用West-ern blot方法检测观察期结束后发病及仍存活的仓鼠脑组织、脾组织中抵抗蛋白酶K的PrPSc。结果当颅内接种稀释度由低到高变化时,仓鼠发病的潜伏期及病程同时也由短到长发生变化。发病仓鼠脑组织中可以检测到PrPSc,但是PrPSc的量在不同的组之间无太大差别。观察期结束后,仍存活的仓鼠脑组织中未检测到具有PK抗性的PrP信号。结论本实验室保存的羊瘙痒因子263K经颅内注射感染仓鼠的LD50为9.2-log10LD50i.c.units/0.001g brain,即当对仓鼠颅内接种10μl羊瘙痒因子263K的10-9.2稀释液时,50%的仓鼠会死亡。

Measurement of LD50 of scrapie agent strain 263K in hamsters through intracerebral route

To determine LD_(50) of scrapie agent strain 263K in hamsters through intracerebral route, hamsters were infected intracerebrally with 10-fold diluted 10% homogenates of the infected hamster brain tissues from dilution of homogenates from 10 -1 to 10 -10 , and the LD_ 50 value was calculated with Reed-Muench's method. The presence of PrP Sc in the brain and spleen tissues of the clinical onset or the living hamsters to resist the action of proteinase K was screened by Western blot analysis. It was found that incubation periods and clinical courses of disease varied greatly with the amounts of infectious agent inoculated, showing a remarkable dose-dependent manner. PrP Sc could be detected in the brain tissues of the diseased hamsters, but the amount of PrP Sc in brains was comparable among different groups, indicating that it was not related to the initiative concentration of the infectious agent. Proteinase K-resistant PrP signal was not observed in the brain tissues of the survival animals receiving 10 -9 and 10 -10 dilutions of agent at the end of observation. It is concluded the LD_ 50 of scrapic agent 263K kept in our laboratory is 9.2-log10, that is, the intracerebral inoculation of 10μl of scrapic agent 263K at dilution of 10 -9.2 causes 50% of death in the infected hamsters.