MM-7基因工程双价疫苗对新疆细毛羊免疫效果的研究

A Study of the Immunoprotective Effectiveness of Bivalent MM7 Gene EngineeringVaccine on Xinjiang Finewool sheep

应用ＭＭ－７基因工程双价疫苗免疫产前１５天的新疆细毛孕母羊，并通过改变产前１５天孕母羊机体免疫水平，由初乳被动免疫羔羊。在免疫孕母羊后１０、２０、３０、４０、５０、６０、７０天分别检测免疫组及对照组血清特异性中和抗体ＩｇＧ及ＩｇＡ动态水平，观察两组腹泻发病率、死亡率情况和ＭＭ－７基因工程双价疫苗的免疫保护效果。实验结果表明该疫苗能迅速激发孕母羊体内特异性中和抗体ＩｇＧ、并在４０天时达到高峰；免疫组发病率为８．５２％，死亡率为３．１９％，而对照组发病率为３４．３４％，死亡率为２１．７７％，两组间发病率与死亡率呈高度显著差异（Ｐ＜０．００５）。

Bivalent MM7 gene engineering vaccine is a vaccine for preventing diarrhea of calves and lambs by combination of two protective antigenic genes, K99 and F41, into an expression vector to make the same bacterial strain express simultaneously two diarrhea antigens. In the present study, pregnant Xinjiang finewool ewes were immunized with this vaccine 15 days antepartum and their lambs were passively immunized through colostrum lactated by these ewes after changing the immunity level of their organisms. Dynamic level of serum specific neutralizing antibodies IgG and IgA of immunized ewes (immunization group) and of controls (control group) was examined 10,20,30,40,50,60 and 70 days after immunization of the pregnant ewes, and morbidity and mortality rates of diarrhea for both the groups were observed as well. The immunoprotective affectiveness of the bivalent MM7 gene engineering vaccine was assessed by the above indexes. The results showed that the vaccine rapidly provoked the development of specific neutralizing antibody IgG in the pregnant ewes with peak on the day 40th and that the morbidity and mortality rates for the immunization group were 8.52% and 3.19%, respectively, and those for the control group were 34.34% and 21.77%, respectively, the difference between the two groups being highly significant ( P<0.005 ). This study confirms that the bivalent MM7 gene engineering vaccine has notable immunoprotective effectiveness.