Coalescence modeling of intrainfection Bacillus anthracis populations allows estimation of infection parameters in wild populations
Coalescence modeling of intrainfection Bacillus anthracis populations allows estimation of infection parameters in wild populations
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DOI：
10.1073/pnas.1920790117
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发表时间：
2020-02-25
影响因子：
11.1
通讯作者：
Turner, Wendy C.
中科院分区：
文献类型：
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作者：
Easterday, W. Ryan;Ponciano, Jose Miguel;Turner, Wendy C.
炭疽芽孢杆菌是炭疽的病原，是一种公认的模式生物。对于炭疽芽胞杆菌和大多数其他传染病，关于自然系统中传播和感染参数的知识在很大程度上包括从严密控制的实验室实验中收集的数据。致命的自然炭疽感染通过在尸体地点的新宿主-病原体接触传播细菌，这可能在前一个宿主死亡数年后发生。从接触到死亡这段时间，我们所有的知识都是基于家畜和实验动物的实验数据。在这里，我们使用一种非侵入性的方法来探索炭疽感染的动态，通过评估炭疽芽孢杆菌在炭疽尸体的末端多样性。我们提出了群体遗传学理论的应用，特别是合并模型，对炭疽杆菌的感染群体进行了估计，以获得感染急性期的持续时间，并将有效群体大小转换为野生平原斑马（Equus quagga）中建立感染的菌落形成单位的数量。最初的种群很小，只有几个群体形成单位，感染速度很快，在野外大约持续1到3天。我们的结果很好地反映了实验数据，表明小的创始种群进展迅速，在几天内杀死宿主。我们相信这种方法适用于来自野生、家养和人类系统的其他细菌性疾病。
Bacillus anthracis, the etiological agent of anthrax, is a well-established model organism. For B. anthracis and most other infectious diseases, knowledge regarding transmission and infection parameters in natural systems, in large part, comprises data gathered from closely controlled laboratory experiments. Fatal, natural anthrax infections transmit the bacterium through new host-pathogen contacts at carcass sites, which can occur years after death of the previous host. For the period between contact and death, all of our knowledge is based upon experimental data from domestic livestock and laboratory animals. Here we use a noninvasive method to explore the dynamics of anthrax infections, by evaluating the terminal diversity of B. anthracis in anthrax carcasses. We present an application of population genetics theory, specifically, coalescence modeling, to intrainfection populations of B. anthracis to derive estimates for the duration of the acute phase of the infection and effective population size converted to the number of colony-forming units establishing infection in wild plains zebra (Equus quagga). Founding populations are small, a few colony-forming units, and infections are rapid, lasting roughly between 1 d and 3 d in the wild. Our results closely reflect experimental data, showing that small founding populations progress acutely, killing the host within days. We believe this method is amendable to other bacterial diseases from wild, domestic, and human systems.