表达HIV-1 gag蛋白的重组乳酸乳球菌诱导小鼠产生体液免疫应答

The humoral immune response in mice induced by recombinant Lactococcus lactis expressing HIV-1 gag

目的分析表达HIV-1 gag蛋白的重组乳酸乳球菌通过口服、滴鼻、皮下注射以及上述3种方式联合免疫小鼠诱导的体液免疫反应。方法将50只BALB/c小鼠随机分成5组,每组10只。表达gag的重组乳酸乳球菌分别通过口服、滴鼻、皮下注射以及上述3种方式联合免疫小鼠,对照组口服含PMG36e空载体的乳酸乳球菌,接种菌量均为109菌落形成单位(CFU),连续免疫3次,每次间隔2周,其中口服和滴鼻每次连续免疫3 d。采集免疫前和每次免疫后2周小鼠的血清,ELISA检测gag特异性的IgG水平。结果表达gag的重组乳酸乳球菌经口服、滴鼻、皮下注射以及3种方式联合免疫均诱导小鼠产生了gag特异性IgG,且联合免疫组gag IgG水平显著高于其他各实验组(P<0.01)。初次免疫后6周,口服和皮下注射免疫组gag IgG水平显著高于滴鼻免疫组(P<0.01)。免疫3次后各组血清中gag抗体的阳性率:口服免疫组分别为40%、40%、90%;滴鼻免疫组分别为10%、20%、20%;皮下免疫组分别为10%、60%、90%;联合免疫组的阳性率在初次免疫后2周已达到100%。结论表达HIV-1 gag的重组乳酸乳球菌载体疫苗经口服、滴鼻、皮下注射及3种方式联合免疫均能诱导小鼠产生特异性的体液免疫反应,多种途径联合免疫可增强乳酸乳球菌载体疫苗的免疫效果。

Objective To analyze the humoral immune response induced by recombinant Lactococcus lactis expressing HIV-1 gag in mice immunized orally,intranasally,subcutaneously or in the combined way of above three. Methods Fifty BALB/c mice were randomly divided into 5 groups,10 mice per group. The mice were immunized consecutively three times at two week intervals with 109 CFU of recombinant Lactococcus lactis expressing gag through oral,intranasal,subcutaneous administration or the mix of them. The mice that were immunized orally with Lactococcus lactis containing PMG36 e served as a control group. The sera of mice were collected before primary immunization and 2 weeks after each immunization to detect the gag specific IgG by ELISA. Results Compared with the control group,the higher titer of serum gag specific IgG was detected in the four groups immunized with recombinant Lactococcus lactis expressing gag,and it was the highest in the mixed immunization group（ P〈0. 01）. The titer of serum gag specific IgG from the oral and subcutaneous immunization groups was significantly higher than that from the intranasal immunization group（ P〈0. 01） 6 weeks after primary immunization.The serum antibody positive rates of the oral immunization group after the first,the second,the third immunization were40%,40%,90%,respectively; the positive rates of the intranasal immunization group were 10%,20%,20%; the positive rates of the subcutaneous immunization group were 10%,60%,90%; the positive rate of the combined immunization group reached 100% 2 weeks after primary immunization. Conclusion Recombinant Lactococcus lactis expressing gag can induce humoral immune response in mice by oral, intranasal, subcutaneous injection or the mix of them, and the mixed immunization can enhance the immune effects of Lactococcus lactis vector vaccine.