Department of Biological Sciences, University of Memphis; Memphis, Tennessee, United States of America.
Department of Natural Resource Ecology and Management, Iowa State University; Ames, Iowa, United States of America.
PLoS Pathog. 2023 Jun 9;19(6):e1011408. doi: 10.1371/journal.ppat.1011408. eCollection 2023 Jun.
Animal hosts can adapt to emerging infectious disease through both disease resistance, which decreases pathogen numbers, and disease tolerance, which limits damage during infection without limiting pathogen replication. Both resistance and tolerance mechanisms can drive pathogen transmission dynamics. However, it is not well understood how quickly host tolerance evolves in response to novel pathogens or what physiological mechanisms underlie this defense. Using natural populations of house finches (Haemorhous mexicanus) across the temporal invasion gradient of a recently emerged bacterial pathogen (Mycoplasma gallisepticum), we find rapid evolution of tolerance (<25 years). In particular, populations with a longer history of MG endemism have less pathology but similar pathogen loads compared with populations with a shorter history of MG endemism. Further, gene expression data reveal that more-targeted immune responses early in infection are associated with tolerance. These results suggest an important role for tolerance in host adaptation to emerging infectious diseases, a phenomenon with broad implications for pathogen spread and evolution.
动物宿主可以通过疾病抵抗力（降低病原体数量）和疾病耐受性（在感染过程中限制损伤而不限制病原体复制）来适应新发传染病。抵抗和耐受机制都可以驱动病原体传播动力学。然而，人们并不清楚宿主耐受性在多大程度上以及在什么生理机制上能快速适应新病原体，或者在多大程度上以及在什么生理机制上能快速适应新病原体。利用家雀（Haemorhous mexicanus）在一种新出现的细菌性病原体（Mycoplasma gallisepticum）的时间入侵梯度上的自然种群，我们发现了对这种耐受性的快速进化（<25 年）。具体来说，MG 地方病历史较长的种群与 MG 地方病历史较短的种群相比，其病理变化较少，但病原体负荷相似。此外，基因表达数据表明，感染早期更有针对性的免疫反应与耐受性有关。这些结果表明，耐受性在宿主对新发传染病的适应中起着重要作用，这一现象对病原体的传播和进化具有广泛的影响。
