Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, USA; Department of Microbiology, Faculty of Veterinary Medicine, Alexandria University, Egypt.
Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, USA; Veterinary Quarantine of Alexandria, General Organization for Veterinary Services, Ministry of Agriculture and Land Reclamation, Egypt.
Tuberculosis (Edinb). 2020 Jan;120:101904. doi: 10.1016/j.tube.2020.101904. Epub 2020 Jan 15.
Studies with Mycobacterium avium subsp. paratuberculosis (Map) in cattle revealed deletion of relA, a global regulator gene, abrogated ability of the mutant to establish a persistent infection, attributed to development of an immune response that cleared infection. Analysis of the recall response demonstrated presence of CD8 cytotoxic T cells that kill intracellular bacteria. Replication of the primary response demonstrated the CTL response could be elicited with the ΔMap/relA mutant or the target of the immune response, a 35 kD membrane protein. Follow up comparative studies with Mycobacterium bovis bacillus Calmette-Guérin (BCG) and a BCG relA (ΔBCG/relA) deletion mutant revealed deletion of relA enhanced the CTL response compared to BCG. Analysis of the cytokine profile of cells proliferating in response to stimulation with BCG or BCG/relA showed increased expression of IFN-γ, TNF-α, and IL-17 by cells stimulated with ΔBCG/relA in comparison with BCG. The proliferative and CTL responses were markedly reduced in response to stimulation with heat killed BCG or ΔBCG/relA. Intracellular bacterial killing was mediated through the perforin, granzyme B (GnzB), and the granulysin pathway. The data indicate relA is the Achilles' heel for pathogenic mycobacteria and deletion may be key to improving efficacy of attenuated vaccines for mycobacterial pathogens.
研究显示，牛分枝杆菌亚种副结核分枝杆菌（Map）中 relA 的缺失，一种全局调控基因的缺失，削弱了突变体建立持续性感染的能力，这归因于免疫反应的发展，该反应清除了感染。对回忆反应的分析表明存在能够杀死细胞内细菌的 CD8 细胞毒性 T 细胞。初次反应的复制表明 CTL 反应可以用ΔMap/relA 突变体或免疫反应的靶标，即 35 kD 膜蛋白来引发。随后对牛分枝杆菌卡介苗（BCG）和 BCG relA（ΔBCG/relA）缺失突变体的比较研究表明，与 BCG 相比，relA 的缺失增强了 CTL 反应。对用 BCG 或 BCG/relA 刺激后增殖的细胞的细胞因子谱进行分析表明，与 BCG 相比，用ΔBCG/relA 刺激的细胞中 IFN-γ、TNF-α 和 IL-17 的表达增加。用热灭活的 BCG 或ΔBCG/relA 刺激后，增殖和 CTL 反应明显减少。细胞内细菌的杀伤是通过穿孔素、颗粒酶 B（GnzB）和颗粒溶素途径介导的。数据表明 relA 是致病性分枝杆菌的阿喀琉斯之踵，缺失可能是改善减毒疫苗对分枝杆菌病原体疗效的关键。
