Institute of Microbiology, Catholic University, Largo A. Gemelli 8, 00168 Rome, Italy.
Infect Immun. 2010 Dec;78(12):5202-13. doi: 10.1128/IAI.00267-10. Epub 2010 Oct 4.
To improve the current vaccine against tuberculosis, a recombinant strain of Mycobacterium bovis bacillus Calmette-Guérin (rBCG) expressing a Mycobacterium tuberculosis vaccine candidate antigen (MPT64) in strong association with the mycobacterial cell wall was developed. To deliver the candidate antigen on the surface, we fused the mpt64 gene to the sequence encoding the PE domain of the PE_PGRS33 protein of M. tuberculosis (to create strain (H)PE-ΔMPT64-BCG), which we have previously shown to transport proteins to the bacterial surface. In a series of protection experiments in the mouse model of tuberculosis, we showed that (i) immunization of mice with (H)PE-ΔMPT64-BCG provides levels of protection significantly higher than those afforded by the parental BCG strain, as assessed by bacterial colonization in lungs and spleens and by lung involvement (at both 28 and 70 days postchallenge), (ii) rBCG strains expressing MPT64 provide better protection than the parental BCG strain only when this antigen is surface expressed, and (iii) the (H)PE-ΔMPT64-BCG-induced MPT64-specific T cell repertoire when characterized by β chain variable region-β chain joining region (BV-BJ) spectratyping indicates that protection is correlated with the ability to recruit gamma interferon (IFN-γ)-secreting T cells carrying the BV8.3-BJ1.5 (172 bp) shared rearrangement. These results demonstrate that (H)PE-ΔMPT64-BCG is one of the most effective new vaccines tested so far in the mouse model of tuberculosis and underscore the impact of antigen cellular localization on the induction of the specific immune response induced by rBCG.
为了改进现有的结核病疫苗，我们构建了一株表达结核分枝杆菌候选疫苗抗原（MPT64）的牛分枝杆菌卡介苗重组菌株（rBCG），该抗原与分枝杆菌细胞壁紧密相关。为了将候选抗原递呈到表面，我们将 mpt64 基因与结核分枝杆菌 PE_PGRS33 蛋白的 PE 结构域编码序列融合（构建了菌株（H）PE-ΔMPT64-BCG），我们之前已经证明该融合蛋白可以将蛋白运输到细菌表面。在一系列结核分枝杆菌小鼠模型保护实验中，我们发现：（i）用（H）PE-ΔMPT64-BCG 免疫小鼠，可显著提高保护水平，与亲本 BCG 菌株相比，肺部和脾脏细菌定植以及肺部受累（攻毒后 28 和 70 天）均明显降低；（ii）rBCG 菌株表达 MPT64 仅当该抗原表面表达时，才能提供比亲本 BCG 菌株更好的保护；（iii）通过 β 链可变区-β 链连接区（BV-BJ）谱型分析鉴定（H）PE-ΔMPT64-BCG 诱导的 MPT64 特异性 T 细胞库，表明保护作用与招募分泌 γ 干扰素（IFN-γ）的 T 细胞的能力相关，这些 T 细胞携带 BV8.3-BJ1.5（172bp）的共有重排。这些结果表明，（H）PE-ΔMPT64-BCG 是迄今为止在结核分枝杆菌小鼠模型中测试的最有效的新型疫苗之一，并强调了抗原细胞定位对 rBCG 诱导的特异性免疫反应的影响。
