An increase in antimycobacterial Th1-cell responses by prime-boost protocols of immunization does not enhance protection against tuberculosis
An increase in antimycobacterial Th1-cell responses by prime-boost protocols of immunization does not enhance protection against tuberculosis
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DOI：
10.1128/iai.74.4.2128-2137.2006
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发表时间：
2006-04-01
影响因子：
3.1
通讯作者：
Leclerc, C
中科院分区：
文献类型：
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作者：
Majlessi, L;Simsova, M;Leclerc, C
百日咳杆菌腺苷酸环化酶（CyaA）类毒素是一种以树突状细胞为靶点的非复制型免疫载体，已成功应用于各种临床前动物模型的预防性和治疗性疫苗接种。在这里，我们研究了CyaA的潜力，它含有强的分枝杆菌免疫原，即，抗原85 A的免疫显性区或6-kDa早期分泌抗原靶（ESAT-6）蛋白的完整序列，以诱导抗分枝杆菌免疫。通过产生T细胞杂交瘤或通过使用来自感染分枝杆菌的小鼠的T细胞，我们首先证明了通过CyaA将85 A或ESAT-6体外递送至抗原呈递细胞导致通过主要组织相容性复合物II类分子加工和呈递与分枝杆菌感染后所展示的表位相同的表位。重要的是，与单独的重组蛋白相比，ESAT-6在体外的呈递在其递送至与CyaA融合的抗原呈递细胞时效率高100倍。在不存在任何佐剂的情况下用CyaA-85 A或CyaA-ESAT-6免疫诱导强的抗原特异性淋巴增殖、白细胞介素-2（IL-2）和γ干扰素（IFN-γ）细胞因子应答，而不产生任何IL-4或IL-5。当用表达ESAT-6的BCG引发后用作加强剂时，CyaA-85 A和CyaA-ESAT-6蛋白能够显著增加增殖和Th 1极化应答的敏感性和强度，特别是抗原特异性产生IFN-γ的CD 4（+）T细胞的频率。然而，用这些CyaA构建体作为单独的亚单位疫苗或作为加强剂免疫不允许诱导或改善针对结核分枝杆菌感染的保护。这些结果质疑了广泛承认的产生IFN-γ的CD 4（+）T细胞的频率与预防结核病的水平之间的相关性。
Bordetella pertussis adenylate cyclase (CyaA) toxoid is a powerful nonreplicative immunization vector targeting dendritic cells, which has already been used successfully in prophylactic and therapeutic vaccination in various preclinical animal models. Here, we investigated the potential of CyaA, harboring strong mycobacterial immunogens, i.e., the immunodominant regions of antigen 85A or the complete sequence of the 6-kDa early secreted antigenic target (ESAT-6) protein, to induce anti mycobacterial immunity. By generating T-cell hybridomas or by using T cells from mice infected with mycobacteria, we first demonstrated that the in vitro delivery of 85A or ESAT-6 to antigen-presenting cells by CyaA leads to processing and presentation, by major histocompatibility complex class II molecules, of the same epitopes as those displayed upon mycobacterial infection. Importantly, compared to the recombinant protein alone, the presentation of ESAT-6 in vitro was 100 times more efficient upon its delivery to antigen-presenting cells in fusion to CyaA. Immunization with CyaA-85A or CyaA-ESAT-6 in the absence of any adjuvant induced strong antigen-specific lymphoproliferative, interleukin-2 (IL-2) and gamma interferon (IFN-gamma) cytokine responses, in the absence of any IL-4 or IL-5 production. When used as boosters after priming with a BCG expressing ESAT-6, the CyaA-85A and CyaA-ESAT-6 proteins were able to strikingly increase the sensitivity and intensity of proliferative and Th1-polarized responses and notably the frequency of antigen-specific IFN-gamma-producing CD4(+) T cells. However, immunization with these CyaA constructs as subunit vaccines alone or as boosters did not allow induction or improvement of protection against Mycobacterium tuberculosis infection. These results question the broadly admitted correlation between the frequency of IFN-gamma-producing CD4(+) T cells and the level of protection against tuberculosis.