Distribution and molecular evolution of bacillus anthracis genotypes in Namibia.
Distribution and molecular evolution of bacillus anthracis genotypes in Namibia.
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DOI：
10.1371/journal.pntd.0001534
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发表时间：
2012
影响因子：
3.8
通讯作者：
Turnbull PC
中科院分区：
文献类型：
--
作者：
Beyer W;Bellan S;Eberle G;Ganz HH;Getz WM;Haumacher R;Hilss KA;Kilian W;Lazak J;Turner WC;Turnbull PC
炭疽芽孢杆菌遗传标记的最新发展使得在炭疽爆发期间和之间监测这种病原体的传播和分布成为可能。在纳米比亚，每年在埃托沙国家公园（ENP）以及私人狩猎和牲畜养殖场都发生炭疽疫情。我们对1983-2010年间收集的384株炭疽芽孢杆菌进行基因分型，以确定ENP内外炭疽暴发可能的流行病学相关性，并分析家畜和野生动物分离株之间的遗传关系。分离株来自20种动物和环境，采用31个标记的多位点vntr分析（MLVA），部分采用12个单核苷酸多态性（SNP）标记和4个单核苷酸重复（SNR）标记进行基因分型。MLVA共鉴定出37个基因型（GT），分别属于4个snp群。在聚类分析和snp分析中，所有GTs均属于a -分支。仅在ENP外发现13个gt，仅在ENP内发现18个gt，在内外同时发现6个gt。分离物之间的遗传距离随着分离时间的增加而增加。然而，在研究开始和结束时，分离株之间的遗传距离相对较小，这表明尽管大多数GTs只是零星发现，但在整个研究期间，三个遗传接近的GTs（占所有ENP分离株的五分之四以上）表现出优势。来自不同寄主物种的分离株之间的遗传距离明显更大，但这种影响很小，这表明尽管物种特异性生态因素可能影响暴露过程，但不同寄主物种之间的传播周期仍然高度相关。利用MLVA数据进一步建立了ENP流行区内GTs可能进化的模型。信噪比分析有助于将分离物与其来源联系起来，但不能阐明流行病学关系。炭疽是由炭疽芽孢杆菌引起的疾病，在其对非洲和世界其他欠发达地区的贫穷农村和城郊社区的影响方面是一种被忽视的人畜共患疾病。纳米比亚的几个地区，特别是埃托沙国家公园，是众所周知的炭疽流行地区，它们共同为调查在牲畜、野生动物和人类以及周围环境中传播的炭疽杆菌的遗传多样性提供了一个很好的模型。本文介绍了现代分子分型技术在纳米比亚炭疽芽孢杆菌基因型多样性分析中的应用，因为它涉及到纳米比亚炭疽芽孢杆菌的时空分布。特别是，我们展示了如何区分由不同毒株引起的疾病暴发与由单一毒株传播引起的疾病暴发，如何追溯暴发毒株的可能起源，以及如何追踪暴发毒株在动物种群内和种群之间的传播途径。所描述的数据与所有与监测、监视和预防炭疽在流行地区传播有关的人员有关。
The recent development of genetic markers for Bacillus anthracis has made it possible to monitor the spread and distribution of this pathogen during and between anthrax outbreaks. In Namibia, anthrax outbreaks occur annually in the Etosha National Park (ENP) and on private game and livestock farms. We genotyped 384 B. anthracis isolates collected between 1983–2010 to identify the possible epidemiological correlations of anthrax outbreaks within and outside the ENP and to analyze genetic relationships between isolates from domestic and wild animals. The isolates came from 20 animal species and from the environment and were genotyped using a 31-marker multi-locus-VNTR-analysis (MLVA) and, in part, by twelve single nucleotide polymorphism (SNP) markers and four single nucleotide repeat (SNR) markers. A total of 37 genotypes (GT) were identified by MLVA, belonging to four SNP-groups. All GTs belonged to the A-branch in the cluster- and SNP-analyses. Thirteen GTs were found only outside the ENP, 18 only within the ENP and 6 both inside and outside. Genetic distances between isolates increased with increasing time between isolations. However, genetic distance between isolates at the beginning and end of the study period was relatively small, indicating that while the majority of GTs were only found sporadically, three genetically close GTs, accounting for more than four fifths of all the ENP isolates, appeared dominant throughout the study period. Genetic distances among isolates were significantly greater for isolates from different host species, but this effect was small, suggesting that while species-specific ecological factors may affect exposure processes, transmission cycles in different host species are still highly interrelated. The MLVA data were further used to establish a model of the probable evolution of GTs within the endemic region of the ENP. SNR-analysis was helpful in correlating an isolate with its source but did not elucidate epidemiological relationships. Anthrax, the disease caused by Bacillus anthracis, is a neglected zoonotic diseases in the context of its impact on poor rural and periurban communities in Africa and other less developed areas of the world. Several regions of Namibia, the Etosha National Park in particular, are well known as being endemic areas for anthrax and, together, provide a good model for the investigation of the genetic diversity of B. anthracis circulating in livestock, wildlife and humans, and surrounding environments. The application of modern molecular strain typing techniques to the analysis of genotypic diversity, as it relates to the spatial and temporal distribution of B. anthracis strains in Namibia, is described in this paper. In particular, we demonstrate how it is possible to distinguish outbreaks of the disease caused by different strains from those caused by the spread of a single strain, to trace an outbreak strain back to its possible origin, and to track the routes of transmission of an outbreak strain within and between animal populations. The data described are relevant to all those concerned with monitoring, surveillance and prevention of the spread of anthrax in endemic areas.
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影响因子：
9.4
作者：
Stratilo, CW;Lewis, CT;Bader, D
通讯作者：
Bader, D
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作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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