Abstract Using the technology of gene immunization, 60 sheep(Ovis aries) were immunized with recombinant plasmid of tandem inhibin gene, pcDNA-DPPISS-DINH and pcDNA-DPPISS-DINH-sC3d3, respectively. The P(Positive absorbancy of blood sera)/N(Negative absorbancy of control) values of antibody against inhibin were detected by ELISA(enzyme-linked immunoassay) and the hormone levels were detected at different stage by RIA(radioimmunoassay) after gene immunization of tandem inhibin in sheep. The results showed that the P/N values of antibody against inhibin in gene immunization groups of pcDNA-DPPISS-DINH and pcDNA-DPPISS-DINH-sC3d3 were higher than those in control group(P＜0.05), respectively, and the levels of antibody against inhibin were rose significantly after the third immunization. The levels of follicle stimulating hormone(FSH) in gene immunization groups were higher than those in control group after the first immunization, and the difference was significant after the second and third immunization (P＜0.05), respectively. The levels of LH(luteinizing hormone), E2(estradiol) and P(progesterone) were all higher than those in control group after the second immunization, but there were no significant differences (P＞0.05). After the third immunization, the levels of E2 and P were higher than those in control group(P＜0.05), and the twinning rates were 22.2% and 30.0%, respectively, which were significantly higher(P＜0.05) than that in the control group. All the results showed that the recombinant plasmid of tandem inhibin gene as vaccine for sheep can stimulate FSH secretion, and molecular adjuvant sC3d(sheep complement 3d) can promote immune response, so as to effect follicle development and induce sheep twinning.
