Extensive genome analysis of Coxiella burnetii reveals limited evolution within genomic groups
Extensive genome analysis of Coxiella burnetii reveals limited evolution within genomic groups
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DOI：
10.1186/s12864-019-5833-8
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发表时间：
2019-06-05
期刊：
影响因子：
4.4
通讯作者：
Titball, Richard W.
中科院分区：
文献类型：
--
作者：
Hemsley, Claudia M.;O'Neill, Paul A.;Titball, Richard W.
贝氏柯克斯体（Coxiellaburnetii）是一种人畜共患病原体，广泛存在于地球仪的野生和家养动物体内，可引起人类Q热。为进一步了解C.贝氏体对于诊断、疫苗和治疗的发展至关重要，但世界许多地方缺乏基因分型数据。英国曾发生过Q热的零星爆发，但当地的C。Burnetii尚未详细研究。Burnetii序列在英国获得。C.来自牛的贝氏体以及一个绵羊样品属于多间隔区序列类型（MST）20，而山羊样品是MST 33（三个基因组）和MST 32（一个基因组），这两种基因型至今尚未被描述为在英国存在。我们基于核心基因组中的单核苷酸多态性（SNP）建立了UK基因组和67个可供临床使用的基因组之间的系统发育关系，这证实了基因组组内菌株的紧密聚类，但也表明这些组内存在亚组。变异主要通过SNPs实现，其中许多是非同义的，从而证实了C. Burnetii基于对现有基因的修饰。最后，我们发现了基因组组特定的基因组内容，这支持了先前建立的基因型的克隆扩张模型，其中一些基因型在各大洲的大规模传播被观察到。英国的burnetii与邻近欧洲国家的相似。作为一个种，C.贝氏体被认为是一种克隆病原体，在核苷酸水平上具有低遗传多样性。在这里，我们提出的证据，在蛋白质水平上的显着变化之间的分离株的不同基因组，这主要影响分泌和膜相关蛋白。我们的结果从而增加了我们对C.全球遗传多样性的了解。burnetii和提供新的见解，这种新兴的人畜共患病原体的演变。
BackgroundCoxiella burnetii is a zoonotic pathogen that resides in wild and domesticated animals across the globe and causes a febrile illness, Q fever, in humans. An improved understanding of the genetic diversity of C. burnetii is essential for the development of diagnostics, vaccines and therapeutics, but genotyping data is lacking from many parts of the world. Sporadic outbreaks of Q fever have occurred in the United Kingdom, but the local genetic make-up of C. burnetii has not been studied in detail.ResultsHere, we report whole genome data for nine C. burnetii sequences obtained in the UK. All four genomes of C. burnetii from cattle, as well as one sheep sample, belonged to Multi-spacer sequence type (MST) 20, whereas the goat samples were MST33 (three genomes) and MST32 (one genome), two genotypes that have not been described to be present in the UK to date. We established the phylogenetic relationship between the UK genomes and 67 publically available genomes based on single nucleotide polymorphisms (SNPs) in the core genome, which confirmed tight clustering of strains within genomic groups, but also indicated that sub-groups exist within those groups. Variation is mainly achieved through SNPs, many of which are non-synonymous, thereby confirming that evolution of C. burnetii is based on modification of existing genes. Finally, we discovered genomic-group specific genome content, which supports a model of clonal expansion of previously established genotypes, with large scale dissemination of some of these genotypes across continents being observed.ConclusionsThe genetic make-up of C. burnetii in the UK is similar to the one in neighboring European countries. As a species, C. burnetii has been considered a clonal pathogen with low genetic diversity at the nucleotide level. Here, we present evidence for significant variation at the protein level between isolates of different genomic groups, which mainly affects secreted and membrane-associated proteins. Our results thereby increase our understanding of the global genetic diversity of C. burnetii and provide new insights into the evolution of this emerging zoonotic pathogen.