肠艾美耳球虫张家口分离株致病性和免疫原性的初步研究

PATHOGENICITY AND IMMUNOGENICITY OF EIMERIA INTESTINALIS ZHANGJIAKOU ISOLATE

肠艾美耳球虫是兔球虫中的主要致病虫种之一，充分研究其生物学特性对兔球虫病的防治有十分重要的意义。本文对肠艾美耳球虫张家口分离株的致病性和免疫原性进行了初步研究。利用3个剂量（1×10^4、1×10^5、1×10^6）的肠艾美耳球虫张家口分离株孢子化卵囊感染35—45日龄无球虫兔，观察临床症状和体重变化，以研究其致病性；21d后，再用1×10。个肠艾美耳球虫孢子化卯囊进行攻毒，监测体重变化和卵囊排出量，评价其免疫原性。结果发现，接种1×10^4个卵囊，即可导致家兔出现临床症状，与空白对照组相比，日增重显著下降，更高感染剂量则会加重症状。攻毒后，免疫组增重未受影响，与空白对照组相比无差异，而不免疫攻毒组体重显著下降；同时免疫组的卵囊排出量显著低于不免疫攻毒组。结果表明肠艾美耳球虫张家口分离株对仔兔具有中等致病性；同时其免疫原性良好。因此可以把该株球虫作为原始株进行早熟虫株选育，并以此为基础，进行兔球虫病疫苗的开发。

Eimeria intestinalis is one relatively high pathogenic specie of rabbit coccidia. Fully understanding of its biological characteristics makes great contribution to the control of rabbit coccidiosis. In this study, the pathogenicity and immunogenicity of E. intestinalis ZJK strain was studied on weaning rabbits by investigating clinical syndrome, body weight loss and oocyst output. Four groups of rabbits were inoculated with sporulated oocysts in the dose of 0, 1 × 10^4 , 1 × 10^5 and 1 × 10^6 , respectively. Then these rabbits were challenged with 1 x 106 oocysts 21 days post inoculation. The results show that the infection with 1 × 10^4 oocysts was sufficient to cause clinical syndrome and body weight loss, compared with the control group. And the groups given more oocysts show worse symptom. After challenge, no difference of the body weight gain was seen between non-infected control group and immunized groups; meanwhile, the oocyst output of the immunized rabbits was much lower than that of the non-immunized but challenged control group. These results suggest that E. intestinalis ZJK strain is of mediate pathogenicity and excellent immunogenicity. Therefore, a precocious line of E. intestinalis based on this strain can be a suitable candidate for the development of a live attenuated vaccine for rabbit coccidiosis.