柔嫩艾美球虫SO7重组蛋白对巨型艾美球虫的免疫保护作用

Cross protective effects of recombinant Eimeria tenella SO7 antigen against E.maxima infections

将大肠杆菌中融合表达的柔嫩艾美球虫(Eimeria tenella)SO7重组蛋白,单独或以鸡重组γ-干扰素为佐剂,于5、12、19日龄对雏鸡进行3次免疫,同时设立E.tenella、巨型艾美球虫(E.maxima)口服卵囊免疫组、未免疫、未攻毒组和未免疫攻毒组作对照,于26日龄用E.maxima进行攻毒,9 d后统计各组的相对增重率和卵囊减少率,探讨其对E.max-ima的交叉保护作用。结果表明:重组蛋白免疫对增重的改善效果与E.maxima口服卵囊免疫组相差不大,γ-干扰素佐剂效应不明显。从卵囊减少率指标角度判断,口服卵囊免疫组效果最佳,为96.35%,重组蛋白免疫组为12.51%,γ-干扰素佐剂组为35.75%。重组SO7蛋白对E.maxima具有一定的交叉免疫保护作用,γ-干扰素对SO7抗原的免疫保护效果具有一定的增强作用。

The fragment of SO7 gene of Eimeria teneUa YZ strain without signal peptide encoding region was cloned into expression vector pGEX-6P-1, insoluble 48 ku GST-SO7 fusion protein was expressed after induced by IPTG, accounted for 37.5 % of total bacterial proteins by Tic-scanning. 5 day old chickens were subcutaneously immunized with SO7 antigen （ 100 microgram per chicken）, and boosted with the same dosage at 12, 19 days of age. Group 1 were given antigen mixed with 5 000 units＇ chicken recombinant interferon-gamma （chIFN-gamma） per dose, group 2 were given nonadjuvanted antigen subcutaneously, group 3 were given 100 sporulated oocysts of E. maxima （orally） at 12 days of age, and group 4 were given 100 sporulated oocysts of E. teneUa （orally） at 12 days of age. Group5 and 6 were unimmunized, served as positive and negative control, respectively. Chickens in all groups were orally challenged with 105 homologous sporulated E. maxima oocysts at 26 days of age, and killed at 8 days postchallenge. The weight gains and oocyst outputs of all the groups were determined and compared with those of the controls. The results demonstrated that the chickens orally immunized with E. maxima oocysts showed best protective effects, while those immunized with nonadjuvanted antigen subcutaneously produced no apparent protective effects. When adjuvanted with chIFN-gamma, recombinant protein showed partial protective effects in terms of oocyst output, but no effects on weight gain（ P 〉 0. 05 ）. Recombinant SO7 antigen of E. tenella induced some responses associated with partial cross-species protection against E. maxima when adjuvanted with chIFN-gamma, which had a potential as a vaecine adjuvant against avian coccidiosis.