The population structure of Clostridium tetani deduced from its pan-genome
The population structure of Clostridium tetani deduced from its pan-genome
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DOI：
10.1038/s41598-019-47551-4
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发表时间：
2019-08-02
影响因子：
4.6
通讯作者：
Bruggemann, Holger
中科院分区：
文献类型：
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作者：
Chapeton-Montes, Diana;Plourde, Lucile;Bruggemann, Holger
破伤风梭菌产生一种强效的神经毒素，破伤风神经毒素（TeNT）是造成世界范围内神经系统疾病破伤风的原因，但可以通过接种破伤风类毒素疫苗有效预防。到目前为止，只有一种类型的TeNT被表征，关于破伤风杆菌菌株之间异质性的信息很少。我们在这里报告了1949年至2017年间从不同地点分离的26株破伤风杆菌菌株的基因组序列。基因组分析显示，破伤风杆菌种群分布在两个系统发育枝上，一个大枝和一个小枝，没有证据表明根据地理起源或分离时间将枝分开。破伤风杆菌的染色体高度保守；相反，编码tent的质粒表现出明显的异质性。TeNT本身在所有菌株中高度保守；最相关的区别是在四种菌株的c端受体结合域插入了四个氨基酸，这可能会影响受体结合特性。其他假定的毒力因子，包括破伤风溶素和胶原酶，在所有基因组中都有编码。这项研究强调了破伤风杆菌的种群结构，并表明破伤风引起的菌株没有经历广泛的进化多样化，从其主要毒力因子的高度保守性判断。
Clostridium tetani produces a potent neurotoxin, the tetanus neurotoxin (TeNT) that is responsible for the worldwide neurological disease tetanus, but which can be efficiently prevented by vaccination with tetanus toxoid. Until now only one type of TeNT has been characterized and very little information exists about the heterogeneity among C. tetani strains. We report here the genome sequences of 26 C. tetani strains, isolated between 1949 and 2017 and obtained from different locations. Genome analyses revealed that the C. tetani population is distributed in two phylogenetic clades, a major and a minor one, with no evidence for clade separation based on geographical origin or time of isolation. The chromosome of C. tetani is highly conserved; in contrast, the TeNT-encoding plasmid shows substantial heterogeneity. TeNT itself is highly conserved among all strains; the most relevant difference is an insertion of four amino acids in the C-terminal receptor-binding domain in four strains that might impact on receptor-binding properties. Other putative virulence factors, including tetanolysin and collagenase, are encoded in all genomes. This study highlights the population structure of C. tetani and suggests that tetanus-causing strains did not undergo extensive evolutionary diversification, as judged from the high conservation of its main virulence factors.