A new evolutionary scenario for the Mycobacterium tuberculosis complex
A new evolutionary scenario for the Mycobacterium tuberculosis complex
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DOI：
10.1073/pnas.052548299
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发表时间：
2002-03-19
影响因子：
11.1
通讯作者：
Cole, ST
中科院分区：
文献类型：
--
作者：
Brosch, R;Gordon, SV;Cole, ST
在总共100株结核分枝杆菌、非洲分枝杆菌、卡涅蒂分枝杆菌、微分枝杆菌和牛分枝杆菌中，对结核杆菌基因组中由插入-缺失事件引起的20个可变区域的分布进行了评估。这种方法表明，大多数这些多态性并不是在结核分枝杆菌复合体的不同菌株中独立发生的，而是由共同祖菌株中古老的、不可逆的遗传事件引起的。根据结核分枝杆菌特异性缺失（TbD1）的存在与否，结核分枝杆菌菌株可分为祖先菌株和“现代”菌株，后者包括北京、哈勒姆和非洲结核分枝杆菌群等主要流行病的代表。此外，通过差异区9和其他随后的缺失，鉴定出以非洲支原体、微支原体和牛支原体为代表的进化谱系在TbD1发生之前从现有结核分枝杆菌菌株的祖先分化出来的DNA的连续丢失。这些发现反驳了经常提出的假设，即结核分枝杆菌是人类结核病的病原，是从牛分枝杆菌进化而来的。卡奈蒂支原体和结核分枝杆菌的祖先没有这些缺失的区域，因此，它们似乎是在非洲支原体之前存在的结核杆菌的直系后代。从结核分枝杆菌谱系中分离出来的牛谱系。这一观察结果表明，结核杆菌的共同祖先类似于结核分枝杆菌或卡内蒂分枝杆菌，很可能已经是一种人类病原体。
The distribution of 20 variable regions resulting from insertion-deletion events in the genomes of the tubercle bacilli has been evaluated in a total of 100 strains of Mycobacterium tuberculosis, Mycobacterium africanum, Mycobacterium canettii, Mycobacterium microti, and Mycobacterium bovis. This approach showed that the majority of these polymorphisms did not occur independently in the different strains of the M. tuberculosis complex but, rather, resulted from ancient, irreversible genetic events in common progenitor strains. Based on the presence or absence of an M, tuberculosis specific deletion (TbD1), M. tuberculosis strains can be divided into ancestral and ''modern'' strains, the latter comprising representatives of major epidemics like the Beijing, Haarlem, and African M. tuberculosis clusters. Furthermore, successive loss of DNA, reflected by region of difference 9 and other subsequent deletions, was identified for an evolutionary lineage represented by M. africanum, M. microti, and M. bovis that diverged from the progenitor of the present M. tuberculosis strains before TbD1 occurred. These findings contradict the often-presented hypothesis that M. tuberculosis, the etiological agent of human tuberculosis evolved from M. bovis, the agent of bovine disease. M. canettii and ancestral M. tuberculosis strains lack none of these deleted regions, and, therefore, seem to be direct descendants of tubercle bacilli that existed before the M. africanum-->M. bovis lineage separated from the M. tuberculosis lineage. This observation suggests that the common ancestor of the tubercle bacilli resembled M. tuberculosis or M. canettii and could well have been a human pathogen already.