Background

Treponema pallidum subsp. pertenue (TPE) is the causative agent of yaws, a multi-stage disease, endemic in tropical regions of Africa, Asia, Oceania, and South America. To date, four TPE strains have been completely sequenced including three TPE strains of human origin (Samoa D, CDC-2, and Gauthier) and one TPE strain (Fribourg-Blanc) isolated from a baboon. All TPE strains are highly similar to T. pallidum subsp. pallidum (TPA) strains. The mutation rate in syphilis and related treponemes has not been experimentally determined yet.

Methodology/Principal findings

Complete genomes of two TPE strains, CDC 2575 and Ghana-051, that infected patients in Ghana and were isolated in 1980 and 1988, respectively, were sequenced and analyzed. Both strains had identical consensus genome nucleotide sequences raising the question whether TPE CDC 2575 and Ghana-051 represent two different strains. Several lines of evidence support the fact that both strains represent independent samples including regions showing intrastrain heterogeneity (13 and 5 intrastrain heterogeneous sites in TPE Ghana-051 and TPE CDC 2575, respectively). Four of these heterogeneous sites were found in both genomes but the frequency of alternative alleles differed. The identical consensus genome sequences were used to estimate the upper limit of the yaws treponeme evolution rate, which was 4.1 x 10⁻¹⁰ nucleotide changes per site per generation.

Conclusions/Significance

The estimated upper limit for the mutation rate of TPE was slightly lower than the mutation rate of E. coli, which was determined during a long-term experiment. Given the known diversity between TPA and TPE genomes and the assumption that both TPA and TPE have a similar mutation rate, the most recent common ancestor of syphilis and yaws treponemes appears to be more than ten thousand years old and likely even older.

中文翻译：

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梅毒螺旋体亚种的两个菌株的完整基因组序列。来自非洲加纳的常识：分离超过7年的样品中的基因组序列相同

背景

梅毒螺旋体亚种 百日咳（TPE）是偏航的病原体，偏航是一种多阶段疾病，在非洲，亚洲，大洋洲和南美的热带地区流行。迄今为止，已经对四种TPE菌株进行了完全测序，包括三种人类来源的TPE菌株（萨摩亚D，CDC-2和Gauthier）和一种从狒狒分离的TPE菌株（Fribourg-Blanc）。所有TPE菌株都与T高度相似。苍白球亚种 苍白球（TPA）菌株。梅毒和相关的treponemes的突变率尚未实验确定。

方法/主要发现

对两个分别感染加纳患者并分别于1980年和1988年分离的TPE菌株CDC 2575和Ghana-051的完整基因组进行了测序和分析。两种菌株具有相同的共有基因组核苷酸序列，这引发了一个问题，即TPE CDC 2575和Ghana-051是否代表两种不同的菌株。有几条证据支持以下事实：两个菌株代表独立的样本，包括显示菌株内异质性的区域（分别在TPE Ghana-051和TPE CDC 2575中有13个和5个菌株内异质位点）。在两个基因组中都发现了四个异质位点，但其他等位基因的频率却不同。使用相同的共有基因组序列来估算航向偏航线粒体进化速率的上限，该上限为4.1 x 10 ^-10 每个世代每个位点的核苷酸变化。

结论/意义

TPE突变率的估计上限略低于E的突变率。大肠杆菌，这是在长期实验中确定的。考虑到TPA和TPE基因组之间的已知多样性，并假设TPA和TPE都具有相似的突变率，最近的梅毒和偏航偏航性色氨酸的祖先似乎已有一万多年的历史，甚至可能更老。