Abstract:

【Objective】 The effect of four different dosages of inhibin gene expressing plasmid on the reproductive capacity of the beef cattle was studied. 【Method】 Fifty eight synchronized beef cattle were randomly assigned to four dosage groups (T1, T2, T3, or T4 , immunized with 0.75, 1.5, 2.25, or 3.0mg of DNA vaccine pCISI harboring two copies of INHal-32, respectively) and two control groups (C1 ,which was injected with 3.0mg pcMV-S plasmid per cattle and C2 , which was injected with physiological saline 3 mL per cattle) to investigate the effect of inhibin gene immunization on development of follicle and corpus luteum, and the booster immunization was given to the cattle on day 21 after the primary immunization. 【Result】 Animals in the four dosage groups had a greater number of large follicles (≥10 mm) than those in group C, and the number of large follicles was significantly larger than those in group C (P＜0.05). Compared to the control group, the number of medium and small follicles in T3 was much larger (P＜0.05), the same as T4. Moreover, luteum corpuses on bilateral ovaries of beef cattle in the four-dosage inhibin gene vaccine-immunized groups were significantly larger than those in group C (P＜0.05). Among the four dosage groups, the largest luteum corpus was in T3, the smallest was in T1, there was a significant difference between T3 and T1. Besides, on day 10 after booster immunization, there was a difference in correlation coefficient between the content of inhibin antibody and size of the mature follicles (r = 0.629, P＜0.05), and the content of inhibin antibody and the size of the corpus lutuem was significantly different (r = 0.651, P＜0.01). 【Conclusion】 These findings demonstrate that inhibin gene vaccine pcISI is able to stimulate development of follicle and corpus luteum. Dosage of 2.25 mg is the best dosage in the study.

Key words: inhibin, gene immunization, follicle, corpus luteum, beef cattle