Abstract:

To assess the immunoefficacy of recombinant Serpin against E. tenella infection in chickens, Serpin gene of E. tenella was cloned and expressed, subsequently, the recombinant Serpin was purified and refolded. Three experimental groups i.e. intramuscular injection, oral administration and intranasal administration groups were designed. At the same time, the challenged and unchallenged groups were also designed as positive and negative control, respectively. Seven-day old chickens were immunized with the recombinant Serpin protein,and boosted with the same method at 14 and 28 days of age. All chickens were orally challenged with sporulated oocysts at 35 days of age and killed at day 7 post challenge. Survival rate ,relative weight gain, oocyst decrease ratio and anticoccidial index were used as the main criteria for the assessment of the protective effect. The results showed the weight gains of the immunized chickens were significantly higher than that of the positive control group (P＜0.05). The oocyst outputs in immunized chickens dropped significantly when compared with the positive control. In comparison with the positive control, the ACI in immunized groups were significantly higher,and the ACI of group immunized orally with recombinant antigen was the highest, the results that the ACI of all immunized group were below 160 implied that the Serpin protein is not an ideal coccidiosis vaccines candidate antigen.