生长抑素基因免疫对湖羊羔羊生长及GH和IGF-Ⅰ的影响

Influence of somatostatin gene immunization on growth and GH and IGF-Ⅰ of Hu lamb

为探讨生长抑素DNA疫苗免疫湖羊的效果,将生长抑素(SS)与乙肝表面抗原(S)基因融合构建真核表达质粒pES/2SS,分别与pE-CpG质粒、细菌DNA、脂质体粗品配合及重新构建的pES/2SS-GMCSF免疫断奶母羔羊,4周后以相同剂量加强免疫1次。结果显示,免疫组的抗体水平高于对照组(P<0.05),首次免疫4周和加强免疫2周后,细菌DNA佐剂组的抗体水平高于生长抑素单独免疫组(P<0.05),其抗体阳性率也为各免疫组最高。全期免疫组抗生长抑素抗体阳性率达36.0%;免疫羊的增重比对照组高18.82%(P<0.01)。加强免疫后2周,免疫组的GH和IGF-Ⅰ水平显著高于对照组(P<0.05),抗体阳性羊的GH和IGF-Ⅰ水平显著高于抗体阴性羊(P<0.01)。分析第2、4、6和10周所检测的各免疫组湖羊生长抑素抗体P/N值、GH、IGF-Ⅰ及周增重之间的相关性,发现生长抑素抗体与GH、IGF-Ⅰ、周增重显著相关(P<0.01),周增重与生长抑素抗体(P<0.01)、GH(P<0.01)、IGF-Ⅰ(P<0.05)显著相关。结果表明:SS基因免疫产生SS抗体,有效中和了内源性SS,影响了相关激素的分泌,促进羔羊生长。

To investigate the immune effect of DNA vaccine against somatostatin （SS） in sheep, the fusion expression plasmid harboring SS and HBsAg S（ pES/2SS ） was used to immunize the female Hu lambs with different adjuvants, such as the pE-CpG plasmid, E. coil DNA, the crude liposome and immunized with reconstructed plasmid pES/2SS- GMCSF. A booster was administrated four weeks later. The resultsshowed that the level of antibody of immunized group was remarkably higher than in the control （P 〈 0.05）. The antibody against SS in the E. coil DNA group was remarkably higher than that in the pES/2SS alone at week 4 after primary immunization and week 2. after booster. The rate of sheep with positive antibody of the E. coli DNA group was the highest in the immunized groups. The rate of sheep with positive antibody of immunized group was 36.0 %. Body weight gain of the immunized group was 18.82 % higher than that of the control （P〈0.01）. At two weeks after booster application, GH and IGF-Ⅰ content of the immunized group was remarkably higher compared to the control （P 〈 0.05）, that of positive antibody higher than that of negative antibody （P〈0.01）. Significant correlations between the Ab P/N value and GH （P〈0.01）, IGF-Ⅰ （P〈0.01） and weekly weight gain （P〈0.01） , also between the weekly body weight gain and the Ab P/N value （P〈0o01）, GH （P 〈 0o 01） and IGF-Ⅰ （P 〈 0o 05） were observed in the groups after SS gene immunization based on the data from the 2nd, 4~, 6~ and10~ weeks. These results suggest that the recombinant somatostatin expression plasmid can stimulate Hu Sheep to produce antibody against SS, neutralize endogenous SS and correspondingly result in a change of GH and IGF-Ⅰ, increase of animal growth.