Tuberculosis (TB) is one of the deadliest human diseases worldwide caused by mycobacterial infection in the lung. Bacillus Calmette-Guerin (BCG) vaccine protects against disseminated TB in children, but its effectiveness is still questionable due to highly variable protections in adolescence and elderly individuals. Targeting the latency M.tb antigen is a recent therapeutic approach to eradicate dormant pathogen that could possibly lead to disease activation. In this study, we aimed to potentiate immune responses elicited against 16 kDa α-crystalline (HspX) tuberculosis latency antigen by incorporation of Combined Adjuvant for Synergistic Activation of Cellular immunity (CASAC). Histidine-tagged recombinant HspX protein was initially produced in Escherichia coli and purified using Ni-NTA chromatography. To evaluate its adjuvanticity, C57BL/6 mice (n = 5) were initially primed and intradermally immunised in 2-weeks interval for 4 rounds with recombinant HspX, formulated with and without CASAC. Humoral and cell-mediated immune responses elicited against HspX antigen were evaluated using ELISA and Flow Cytometry. Our findings showed that CASAC improved humoral immunity with increased antigen-specific IgG1 and IgG2a antibody response. Stronger CD8+ and Th1-driven immunity was induced by CASAC formulation as supported by elevated level of IFN-γ, TNF-α, IL-12 and IL-17A; and with low IL-10 secretion. Interestingly, adjuvanted HspX vaccine triggered a higher percentage of effector memory T-cell population than those immunised with unadjuvanted vaccine. In conclusion, CASAC adjuvant has great potential to enhance immunogenicity elicited against HspX antigen, which could be an alternative regimen to improve the efficacy of future therapeutic vaccine against Mycobacterium tuberculosis.

中文翻译：

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通过掺入复合分子佐剂（CASAC）增强针对结核分枝杆菌HspX抗原的免疫应答。

肺结核（TB）是全球范围内由肺中的分枝杆菌感染引起的最致命的人类疾病之一。卡介苗芽孢杆菌（BCG）疫苗可预防儿童传播的结核病，但由于青春期和老年人的保护措施差异很大，其有效性仍然值得怀疑。靶向潜伏期M.tb抗原是一种根除可能导致疾病激活的休眠病原体的最新治疗方法。在这项研究中，我们旨在通过掺入细胞免疫协同激活的联合佐剂来增强针对16 kDaα晶体（HspX）结核潜伏期抗原的免疫应答。组氨酸标签的重组HspX蛋白最初是在大肠杆菌中产生的，并使用Ni-NTA色谱法进行纯化。要评估其辅助性，首先对C57BL / 6小鼠（n = 5）进行初次免疫，并用重组HspX（有无CASAC配制）以2周的间隔进行2轮皮内免疫。使用ELISA和流式细胞术评估了针对HspX抗原的体液和细胞介导的免疫反应。我们的发现表明，CASAC通过增加抗原特异性IgG1和IgG2a抗体反应来改善体液免疫。IFN-γ，TNF-α，IL-12和IL-17A水平升高支持CASAC制剂诱导更强的CD8 +和Th1驱动免疫力。且IL-10分泌量低。有趣的是，佐剂化的HspX疫苗引发的效应记忆T细胞群的百分比要高于未佐剂的疫苗。总之，CASAC佐剂具有增强针对HspX抗原的免疫原性的巨大潜力，