Experimental evidence for stabilizing selection on virulence in a bacterial pathogen.
Experimental evidence for stabilizing selection on virulence in a bacterial pathogen.
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DOI：
10.1002/evl3.203
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发表时间：
2020-12
影响因子：
5
通讯作者：
Giraudeau M
中科院分区：
文献类型：
--
作者：
Bonneaud C;Tardy L;Hill GE;McGraw KJ;Wilson AJ;Giraudeau M
毒力-传播权衡假说为预测病原体毒力进化提供了主导理论基础，但实证测试很少，特别是在病原体出现时。该假设的核心预测是，由于感染持续时间和传播率之间的权衡，病原体适应性在中等毒力时最大化。然而，获得足够数量的具有对比毒力的病原体分离株来测试关键病原体性状之间的关系形状，并且在不混淆进化的宿主保护性免疫（如出现时预期）的情况下这样做是具有挑战性的。在这里，我们将 55 株细菌病原体分离株（鸡毒支原体）接种到从未接触过这种疾病的种群中的非耐药家雀 (Haemorhous mexicanus) 中。分离株是在疾病爆发后 20 年间在暴露于疾病的家雀种群中收集的，其毒力差异显着。我们发现病原体毒力与未感染哨兵的传播率之间存在正线性关系，支持权衡假设的核心假设。此外，为了支持关键预测，没有证据表明对病原体毒力的定量代理进行定向选择，相反，中等毒力的分离株是最适合的。然而，令人惊讶的是，毒力和传播率之间的正相关关系并没有像通常假设的那样受到病原体载量或复制率变化的支持。我们的结果表明，即使毒力和传播与病原体负荷无关，在新宿主物种中出现疾病时，选择也有利于中等毒力的病原体。
The virulence‐transmission trade‐off hypothesis has provided a dominant theoretical basis for predicting pathogen virulence evolution, but empirical tests are rare, particularly at pathogen emergence. The central prediction of this hypothesis is that pathogen fitness is maximized at intermediate virulence due to a trade‐off between infection duration and transmission rate. However, obtaining sufficient numbers of pathogen isolates of contrasting virulence to test the shape of relationships between key pathogen traits, and doing so without the confounds of evolved host protective immunity (as expected at emergence), is challenging. Here, we inoculated 55 isolates of the bacterial pathogen, Mycoplasma gallisepticum, into non‐resistant house finches (Haemorhous mexicanus) from populations that have never been exposed to the disease. Isolates were collected over a 20‐year period from outbreak in disease‐exposed populations of house finches and vary markedly in virulence. We found a positive linear relationship between pathogen virulence and transmission rate to an uninfected sentinel, supporting the core assumption of the trade‐off hypothesis. Further, in support of the key prediction, there was no evidence for directional selection on a quantitative proxy of pathogen virulence and, instead, isolates of intermediate virulence were fittest. Surprisingly, however, the positive relationship between virulence and transmission rate was not underpinned by variation in pathogen load or replication rate as is commonly assumed. Our results indicate that selection favors pathogens of intermediate virulence at disease emergence in a novel host species, even when virulence and transmission are not linked to pathogen load.
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影响因子：
2.6
作者：
Ben-Ami F
通讯作者：
Ben-Ami F
影响因子：
2.4
作者：
ANDERSON, RM;MAY, RM
通讯作者：
MAY, RM
DOI：
10.1073/pnas.0708559104
发表时间：
2007-10-30
影响因子：
11.1
作者：
Fraser, Christophe;Hollingsworth, T. Deirdre;Hanage, William P.
通讯作者：
Hanage, William P.
影响因子：
3.3
作者：
Doumayrou, Juliette;Avellan, Astrid;Michalakis, Yannis
通讯作者：
Michalakis, Yannis
影响因子：
1.7
作者：
Adelman JS;Mayer C;Hawley DM
通讯作者：
Hawley DM