Korean Journal of Veterinary Research 1993;33(4):657-664.
 Effects of γ-Irradiation from Cobalt-60 on Immunogenicity of Eimeria tenella Hee-jeong Youn1, Yung-bai Kang1, Du-hwan Jang2 1Department of Parasitology, Veterinary Research Institute of RDA in Korea2Department of Parasitology, College of Veterinary Medicine, Seoul National University Cobalt-60 γ-선 조사가 Eimeria tenella 의 면역원성에 미치는 영향 윤희정1, 강영배1, 장두환2 1가축위생연구소2서울대학교 수의과대학 Abstract To reveal the immunogenicity of ${gamma}-irradiated$ E tenella and its progeny, a series of experiments on the effects of Cobalt-to ${gamma}-irradiation$ was performed. The SPF chickens inoculated with diffenrt doses of inoculum were challenged with $1{ imes}10^5$ oocysts of virulent E tenella. The levels of 100 Gy ${gamma}-irradiation$ from $^{60}Co$ and of inoculum with $1{ imes}10^4$ oocysts were recognized as proper as immunogen by comparison of survival rates, body weight gains, blood in feces and lesion scores in the chickens. In these trials of challenge with virulent E tenella after inoculation with $1{ imes}10^4$ oocysts of the ${gamma}-irradiated$ E tenella and its progeny, the survival rates of the chickens challenged with the virulent E tenella after immunization with the 1st and the 3rd progeny groups of ${gamma}-irradiated$ E tenella oocysts were higher(l00%) than that(87.0%) of the challenged control group. The signs of blood in feces and the lesion scores were seen markedly lower with the ourput of the smaller number of oocysts, i.e. OPG 103,900 and 25,800 in the groups of the 1st and the 3rd progeny, respectively, than those(OPG 1,658,900) of the challenged control group. The body weight gains of the 1st and the 3rd progeny groups, the 1st week and the 2nd week after challenge, were higher (2.6g and 155.4g, 11.6g and 168.9g respectively) than those(-85.8g and 63.6g, respectively) of the challenged control group, and the feed conversion ratios(FCR 3.28 and 2.96) of the 1st and the 3rd progeny groups were lower than that(FCR 5.60) of the groups challenged control group. The anticoccidial indices(70.5 and 93.9) of the groups challenged with the virulent oocysts of E tenella after immunization with the 1st and the 3rd progeny of the ${gamma}-irradiated$ E tenella were significantly higher than that (ACI -81.9) of the challenged control group. It was thought that the immunogenicity of ${gamma}-irradiated$ E tenella would be increase according to increase the number of generation passaged in chicken. That might be because of increasing the pathogenicity of ${gamma}-irradiated$ E tenella according to increase the number of generation passaged in chicken. Key Words: Eimeria tenella, Cobalt-60, ${gamma}-irradiation$, the 1st and the 3rd progeny, immunogenicity, anticoccidial index