钴^(60)丙线控制刚地弓形虫(Toxoplasma gondii)包囊感染性的研究

STUDY ON THE EFFECT OF IRRADIATION ON THE INFECTIVITY OF TOXOPLASMA GONDII CYSTS

实验采用 NT 株刚地弓形虫,将含有该虫株包囊的鼠脑匀浆,分别用0.1～1.0KGy 钴^(60)丙线剂量照射,经腹腔接种小鼠后50d,用脑组织压印涂片检查弓形虫包囊和血清 IHA 试验检测抗体及盲传试验考查辐照效果。0.5KGy 及以下剂量对小鼠仍具感染性,感染率达75～25%,但弓形虫包囊的存活力随辐照剂量的增大而减弱。0.75KGy 及1.0KGy 剂量照射的包囊,对小鼠无感染性,同样经幼猫试验获得与上述相似的结果。进一步实验证明:丙线控制 NT 株弓形虫包囊感染性的最小有效剂量接近于0.55KGy。

Homogenate of mouse brains harbouring Toxoplasma gondii cysts of NT strain were irradiated at doses of 0.1,0.25,0.50,0.75 and 1.00 KGy of Cobalt-60 gamma-ray and then inoculated into mice.The Results showed that the Positive rate and density of cysts of mice infected had a declining tendency along with the rise of dose.the positive rates in 0.1,0.25,0.5 KGy and control groups were 75%(6/8),59%(4/8),25%(2/8) and 100%(8/8)respectively.The mean numbers of cysts per 400mm^2 of impression smea of mouse brains were 1.73,0.92,0.83 and 3.13 correspondingly.The GRMT of IHA tests were 161,90.5 and 64 in groups of 0.1,0.25,0.50KGyy and 203 in control group on the 50th day after inoculation.Similar results were obtained in kittens.Especially at a dose of 0.75 KGy,cyst or oocyst has never been found in mice and kitten.All IHA and subpassage were also negative.A further experiment at doses of 0.5,0.55,0.60, 0.65,0.70and 0.75KGy was carried out.The results showed that the positive rate of cysts in control group was 100%,that of 0.5KGy group was 14%(1/7).No cyst was found in other groups and IHA tests and subpassages showed negative too.It was concluded that effectivc dose and the minimum effe:tive dose of gamma-ray to contror the infectivity of NT strain toxoplasma cysts were 0.75 KGy and 0.55 KGy respectively. This project is supported by Joint FAO/IAEA Division of Nuclear Technipues in Food and Agriculture.