Early Secreted Antigenic Target 6 kDa (ESAT6) is a potent immunogenic protein secreted by the bacteria causing tuberculosis, i.e., Mycobacterium tuberculosis. Another highly immunogenic culture filtrate protein whose gene is linked to ESAT6/ESXA is known as CFP10/ESXB. Because of their high immunogenicity and specificity to M. tuberculosis, these proteins have been proposed as a vaccine to prevent tuberculosis and diagnose the active/latent disease. However, the same proteins cannot be used for prevention and diagnosis because immunized but healthy people will also show a positive response and be falsely reported as diseased. Therefore, in this review article, the search was made to identify if any other ESAT6-like proteins exist in the M. tuberculosis genome. The search identified 21 additional ESAT-like proteins, i.e., ESXC to ESXW. Immunological characterization has shown that some of them (especially ESXV) were able to induce immune responses in vitro with cells obtained from tuberculosis patients and healthy donors. When the protein ESXV was tested in different recombinant forms (expressed in Escherichia coli, mycobacterial vectors, and DNA plasmids) and injected in mice, immune responses were induced to multiple epitopes of the protein. Furthermore, immunization of mice with ESXV protected them from infection with M. tuberculosis. The same protein was also able to protect mice against the induction of asthma. These results suggest that ESXV has the potential to protect against two major diseases of the world, i.e., tuberculosis and asthma, and hence may be used as a common vaccine for both diseases.

中文翻译：

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结核分枝杆菌特异性 ESAT6 样蛋白的化学和生物学特征及其预防结核病和哮喘的潜力。

早期分泌抗原靶点 6 kDa (ESAT6) 是由结核病细菌（即结核分枝杆菌）分泌的一种强效免疫原性蛋白。另一种高度免疫原性的培养物滤过蛋白，其基因与 ESAT6/ESXA 连锁，称为 CFP10/ESXB。由于它们的高免疫原性和对结核分枝杆菌的特异性，这些蛋白质已被提议作为预防结核病和诊断活动性/潜伏性疾病的疫苗。然而，相同的蛋白质不能用于预防和诊断，因为免疫但健康的人也会表现出阳性反应，并被错误地报告为患病。因此，在这篇综述文章中，我们进行了搜索以确定结核分枝杆菌基因组中是否存在任何其他 ESAT6 样蛋白。搜索发现了另外 21 个 ESAT 样蛋白，即 ESXC 至 ESXW。免疫学表征表明，其中一些（尤其是 ESXV）能够利用从结核病患者和健康捐赠者获得的细胞在体外诱导免疫反应。当 ESXV 蛋白以不同的重组形式（在大肠杆菌、分枝杆菌载体和 DNA 质粒中表达）进行测试并注射到小鼠体内时，会诱导针对该蛋白的多个表位的免疫反应。此外，用 ESXV 对小鼠进行免疫可以保护它们免受结核分枝杆菌的感染。同样的蛋白质还能够保护小鼠免受哮喘的诱发。这些结果表明，ESXV具有预防世界上两种主要疾病，即结核病和哮喘的潜力，因此可以用作这两种疾病的通用疫苗。