Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.
Microb Pathog. 2011 Jun;50(6):331-5. doi: 10.1016/j.micpath.2011.02.008. Epub 2011 Mar 21.
Three hypervirulent strains of Mycobacterium tuberculosis isolated from patients suffering from tuberculous meningitis were shown to grow more rapidly inside human macrophages in our previous study. In the current investigation, genomic polymorphisms in these hypervirulent strains were examined using microarray-based comparative genomic hybridization. Among the five genomic polymorphisms identified, two are in-frame deletion (Rv0071/4 and Rv0613c/6c), two are frameshift deletion (Rv1758' and Rv2820c'), and one is gene replacement (Mb3159). The five genomic polymorphisms were transformed into Mycobacterium smegmatis strain mc(2)155 and the survivability of recombinants inside the human monocytic cell line THP-1 was measured. Interestingly, only the recombinant possessing the Rv2820c' survived significantly better than the vector control after 6 h of ex vivo infection (P < 0.001, one-way ANOVA). The Rv2820c' was later transformed into Mycobacterium marinum strain M and the recombinant was used to infect zebrafish. The in vivo infection also showed that the zebrafish infected with the recombinant possessing the Rv2820c' died significantly faster than the vector control (P = 0.006, log-rank test). The 3' truncation in the Rv2820c' was caused by the Beijing/W-defining deletion RD207 and is commonly found in the Beijing/W strains. The current study demonstrated that the truncated Rv2820c of Beijing/W strains could enhance mycobacterial virulence ex vivo and in vivo. This enhancement, however, was not observed for the intact Rv2820c of the non-Beijing/W strains. The presence of the 3' truncated portion of Rv2820c may interfere with overall protein folding and render the Rv2820c of the non-Beijing/W strains non-functional.
在我们之前的研究中，从患有结核性脑膜炎的患者中分离出的三株高毒力结核分枝杆菌菌株在人类巨噬细胞内的生长速度更快。在当前的研究中，使用基于微阵列的比较基因组杂交技术检查了这些高毒力菌株的基因组多态性。在鉴定的五个基因组多态性中，有两个是框内缺失（Rv0071/4 和 Rv0613c/6c），两个是移码缺失（Rv1758' 和 Rv2820c'），一个是基因替换（Mb3159）。将这五个基因组多态性转化为分枝杆菌 smegmatis 菌株 mc(2)155，并测量重组体在人单核细胞系 THP-1 内的生存能力。有趣的是，只有携带 Rv2820c'的重组体在体外感染 6 小时后比载体对照存活得更好（P < 0.001，单向方差分析）。Rv2820c' 后来被转化为分枝杆菌 marinum 菌株 M，并用重组体感染斑马鱼。体内感染也表明，携带 Rv2820c'的重组体感染的斑马鱼死亡速度明显快于载体对照（P = 0.006，对数秩检验）。Rv2820c'的 3'截断是由北京/W 定义的缺失 RD207 引起的，并且常见于北京/W 菌株中。本研究表明，北京/W 菌株的截断 Rv2820c 可增强分枝杆菌的体外和体内毒力。然而，对于非北京/W 菌株的完整 Rv2820c 并未观察到这种增强。Rv2820c 的 3'截断部分的存在可能会干扰整体蛋白质折叠，并使非北京/W 菌株的 Rv2820c 失去功能。
