EcoHealth Alliance, New York, New York, United States of America; Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America.
EcoHealth Alliance, New York, New York, United States of America.
PLoS Negl Trop Dis. 2014 Mar 20;8(3):e2738. doi: 10.1371/journal.pntd.0002738. eCollection 2014 Mar.
Emerging bacterial zoonoses in bats and rodents remain relatively understudied. We conduct the first comparative host-pathogen coevolutionary analyses of bacterial pathogens in these hosts, using Bartonella spp. and Leptospira spp. as a model.
METHODOLOGY/PRINCIPAL FINDINGS: We used published genetic data for 51 Bartonella genotypes from 24 bat species, 129 Bartonella from 38 rodents, and 26 Leptospira from 20 bats. We generated maximum likelihood and Bayesian phylogenies for hosts and bacteria, and tested for coevoutionary congruence using programs ParaFit, PACO, and Jane. Bartonella spp. and their bat hosts had a significant coevolutionary fit (ParaFitGlobal = 1.9703, P≤0.001; m2 global value = 7.3320, P≤0.0001). Bartonella spp. and rodent hosts also indicated strong overall patterns of cospeciation (ParaFitGlobal = 102.4409, P≤0.001; m2 global value = 86.532, P≤0.0001). In contrast, we were unable to reject independence of speciation events in Leptospira and bats (ParaFitGlobal = 0.0042, P = 0.84; m2 global value = 4.6310, P = 0.5629). Separate analyses of New World and Old World data subsets yielded results congruent with analysis from entire datasets. We also conducted event-based cophylogeny analyses to reconstruct likely evolutionary histories for each group of pathogens and hosts. Leptospira and bats had the greatest number of host switches per parasite (0.731), while Bartonella and rodents had the fewest (0.264).
CONCLUSIONS/SIGNIFICANCE: In both bat and rodent hosts, Bartonella exhibits significant coevolution with minimal host switching, while Leptospira in bats lacks evolutionary congruence with its host and has high number of host switches. Reasons underlying these variable coevolutionary patterns in host range are likely due to differences in disease-specific transmission and host ecology. Understanding the coevolutionary patterns and frequency of host-switching events between bacterial pathogens and their hosts will allow better prediction of spillover between mammal reservoirs, and ultimately to humans.
蝙蝠和啮齿动物中的新兴细菌性人畜共患病仍相对研究不足。我们使用巴尔通体（Bartonella）和钩端螺旋体（Leptospira）作为模型，对这些宿主中的细菌病原体进行了首次比较宿主-病原体协同进化分析。
方法/主要发现：我们使用了 51 种来自 24 种蝙蝠物种的巴尔通体基因型、129 种来自 38 种啮齿动物的巴尔通体和 26 种来自 20 种蝙蝠的钩端螺旋体的已发表遗传数据。我们为宿主和细菌生成了最大似然和贝叶斯系统发育树，并使用 ParaFit、PACO 和 Jane 程序测试协同进化一致性。巴尔通体和它们的蝙蝠宿主具有显著的协同进化适应性（ParaFitGlobal = 1.9703，P≤0.001；m2 全局值 = 7.3320，P≤0.0001）。巴尔通体和啮齿动物宿主也表现出强烈的共进化模式（ParaFitGlobal = 102.4409，P≤0.001；m2 全局值 = 86.532，P≤0.0001）。相比之下，我们无法拒绝钩端螺旋体和蝙蝠之间的物种形成事件的独立性（ParaFitGlobal = 0.0042，P = 0.84；m2 全局值 = 4.6310，P = 0.5629）。对新世界和旧世界数据集子集的单独分析得出的结果与整个数据集的分析结果一致。我们还进行了基于事件的共系统发育分析，以重建每组病原体和宿主的可能进化历史。钩端螺旋体和蝙蝠每寄生虫发生的宿主转换次数最多（0.731），而巴尔通体和啮齿动物的宿主转换次数最少（0.264）。
结论/意义：在蝙蝠和啮齿动物宿主中，巴尔通体与宿主表现出显著的协同进化，而宿主转换最少，而蝙蝠中的钩端螺旋体与宿主缺乏进化一致性，且宿主转换次数较多。导致这些宿主范围的可变协同进化模式的原因可能是由于疾病特异性传播和宿主生态的差异。了解细菌病原体与其宿主之间的协同进化模式和宿主转换事件的频率，将有助于更好地预测哺乳动物宿主之间的溢出效应，并最终预测到人类。
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