结核分枝杆菌Ag85A DNA疫苗的免疫原性和治疗作用

目的 研究结核分枝杆菌Ag85A DNA 疫苗的免疫原性和治疗作用.方法 40只BALB/c小鼠随机分为4组,分别用生理盐水、pVAX1载体、微卡菌苗、Ag85A DNA 疫苗免疫,每2周肌内注射1次,共3次.研究 Ag85A DNA 疫苗的免疫原性.用结核分枝杆菌H37Rv通过尾静脉注射40只BALB/c小鼠,分别用生理盐水、pVAX1载体、利福平、Ag 85A DNA 疫苗治疗.治疗结束后2周杀鼠,观察肺和脾病理改变,称取重量、做菌落计数,用ELISPOT方法检测小鼠分泌γ干扰素(IFN-γ)的T淋巴细胞斑点数.结果 与其他组比较,Ag 85A DNA疫苗能诱导产生大量Ag85A特异的分泌IFN-γ 的T淋巴细胞(S=11.832,P=0.0080).肺组织病理显示:生理盐水组肺组织病变严重、广泛;载体组比生理盐水组病变略轻,但病变仍较重、广泛;Ag 85A DNA 疫苗组肺组织病变减轻、局限,3/5区域肺泡结构完整,清晰;利福平组肺组织无病变.与生理盐水组比较,Ag85A DNA 疫苗组和利福平组肺脏菌落数分别减少0.73 log和2.11 log;肝脏菌落数分别减少0.88 log和2.11 log(P<0.01).结论 Ag85A DNA 疫苗对小鼠结核病具有较好的治疗效果.

Therapeutic effects and immunogenicity of Ag85A DNA vaccines from Mycobacterium tuberculosis

Objective To evaluate the therapeutic effects and immunogenicity of Ag85A DNA vaccines in mouse models of M.tuberculosis infection to develop new immunotherapeutic agents for treatment of tuberculosis.Methods Fourty female BALB/c mice were immunized intramuscularly with saline,plasmid vector pVAX1,M.vaccae vaccine and Ag85A DNA for three times at two-week intervals to evaluate immunogenicity of Ag85A DNA vaccines.Fourty female BALB/c mice were infected intravenously via the tail vein with M.tuberculosis H37RV,then randomly divided into 4 groups based and treated as follow at the third day after infection:saline,plasmid vector,rifampin,Ag 85A plasmid DNA vaccines.DNA vaccines were injected intramuscularly 3 times at two-week intervals.Mice were sacrificed two weeks after the final immunization.The lungs and spleens from the mice were taken and their pathological changes,weight and number of mycobacterial colony were examined.ELISPOT assay for IFN-γ was performed with ELISPOT assay kit as instructed by the manufacture.Results Ag85A DNA vaccines had a significantly increased amount of T cells that secreted IFN-γ in response to Ag85A protein than mice treated with control groups(S=11.832,P=0.0080).The histopathological changes in lung showed that the lung lesions were severe and extensive in saline and plasmid vector pVAX1 group,the lung lesions were slight and limited,there were relatively clear and normal structure of alveoli in Ag85A DNA vaccine group,there were no lung lesions in RFP group.Compared with saline group,Ag85A DNA vaccine group and RFP group reduced the pulmonary bacterial loads by 0.73 log and 2.11 log,liver bacterial loads by 0.88 log and 2.11 log(P<0.01),respectively.Conclusions The immunotherapeutic effects of Ag85A DNA are significant in the mouse model of tuberculosis.