Jenkins M C, Chute M B, Danforth H D
Immunology and Disease Resistance Laboratory, USDA, Beltsville, MD 20705, USA.
Avian Dis. 1997 Jul-Sep;41(3):702-8.
In an effort to develop an attenuated coccidiosis vaccine against coccidiosis, we exposed Eimeria maxima oocysts to an optimum dose of gamma irradiation (17 kRad) that does not affect sporozoite invasion of the intestinal mucosa but does prevent asexual parasite development. Irradiated E. maxima oocysts were suspended in gelatin slabs and placed in battery cages for ingestion by 1-day-old chickens. Separate groups of chickens were given gelatin slabs containing nonirradiated E. maxima oocysts or were inoculated per os with either irradiated or nonirradiated E. maxima oocysts. Chickens infected with irradiated or nonirradiated oocysts by either oral inoculation or gel delivery showed a dose-dependent protection against weight loss associated with E. maxima challenge compared with unimmunized controls. In general, nonirradiated oocysts elicited protective immunity at lower immunization doses compared with irradiated oocysts. These experiments were extended to a floor pen study wherein 1-day-old male and female broiler chickens were given irradiated or nonirradiated E. maxima oocysts in gelatin slabs in hatching boxes and challenged at 4 wk of age. A significant reduction (P < 0.05) in lesion scores was observed for chickens immunized with either irradiated or nonirradiated oocysts compared with unimmunized controls. Although no significant difference (P > 0.05) was observed in weight gain between these groups, both male and female chickens inoculated with irradiated E. maxima oocysts showed about a 10% greater weight gain than unimmunized controls. For both male and female chickens, average weights at challenge were greater in groups that were immunized with 17-kRad-irradiated E. maxima oocysts compared with those animals immunized with nonirradiated oocysts.
为了研发一种针对球虫病的减毒球虫病疫苗，我们将巨型艾美耳球虫卵囊暴露于最佳剂量的γ射线照射（17千拉德）下，该剂量不会影响子孢子对肠黏膜的侵袭，但能阻止寄生虫的无性发育。将经照射的巨型艾美耳球虫卵囊悬浮在明胶板中，放置在层架式鸡笼中供1日龄雏鸡采食。将不同组的雏鸡分别给予含有未照射巨型艾美耳球虫卵囊的明胶板，或经口接种照射或未照射的巨型艾美耳球虫卵囊。与未免疫的对照组相比，通过口服接种或明胶递送感染照射或未照射卵囊的雏鸡，在抵抗与巨型艾美耳球虫攻击相关的体重减轻方面表现出剂量依赖性保护作用。一般来说，与照射卵囊相比，未照射卵囊在较低免疫剂量下即可引发保护性免疫。这些实验扩展到了地面平养研究，其中在孵化箱中给1日龄的雄性和雌性肉鸡投喂含有照射或未照射巨型艾美耳球虫卵囊的明胶板，并在4周龄时进行攻毒。与未免疫的对照组相比，用照射或未照射卵囊免疫的雏鸡的病变评分显著降低（P<0.05）。尽管这些组之间在体重增加方面未观察到显著差异（P>0.05），但接种照射巨型艾美耳球虫卵囊的雄性和雌性雏鸡的体重增加均比未免疫的对照组高约10%。对于雄性和雌性雏鸡，与用未照射卵囊免疫的动物相比，用17千拉德照射的巨型艾美耳球虫卵囊免疫的组在攻毒时的平均体重更高。
