Ashoka University, Sonepat, India.
Savannah River Ecology Laboratory, University of Georgia, Aiken, United States.
Elife. 2021 Sep 21;10:e68874. doi: 10.7554/eLife.68874.
Researchers worldwide are repeatedly warning us against future zoonotic diseases resulting from humankind's insurgence into natural ecosystems. The same zoonotic pathogens that cause severe infections in a human host frequently fail to produce any disease outcome in their natural hosts. What precise features of the immune system enable natural reservoirs to carry these pathogens so efficiently? To understand these effects, we highlight the importance of tracing the evolutionary basis of pathogen tolerance in reservoir hosts, while drawing implications from their diverse physiological and life-history traits, and ecological contexts of host-pathogen interactions. Long-term co-evolution might allow reservoir hosts to modulate immunity and evolve tolerance to zoonotic pathogens, increasing their circulation and infectious period. Such processes can also create a genetically diverse pathogen pool by allowing more mutations and genetic exchanges between circulating strains, thereby harboring rare alive-on-arrival variants with extended infectivity to new hosts (i.e., spillover). Finally, we end by underscoring the indispensability of a large multidisciplinary empirical framework to explore the proposed link between evolved tolerance, pathogen prevalence, and spillover in the wild.
世界各地的研究人员一再警告我们要警惕人类对自然生态系统的入侵可能导致未来的人畜共患病。在人类宿主中引起严重感染的相同人畜共患病原体在其自然宿主中经常不会产生任何疾病结果。是什么确切的免疫系统特征使自然宿主能够如此有效地携带这些病原体？为了了解这些影响，我们强调了追踪病原体在宿主中耐受的进化基础的重要性，同时从它们不同的生理和生活史特征以及宿主-病原体相互作用的生态背景中得出启示。长期共同进化可能使宿主能够调节免疫并对人畜共患病原体产生耐受性，从而增加其循环和传染性。这些过程还可以通过允许循环株之间发生更多的突变和基因交换，从而在遗传上产生更多样化的病原体库，从而携带具有更长传染性的罕见活到达新宿主的变体（即溢出）。最后，我们强调了需要一个大型多学科经验框架来探索在野外进化耐受、病原体流行和溢出之间提出的联系。
