Opportunistic pathogens are associated with a number of chronic human infections, yet the evolution of virulence in these organisms during chronic infection remains poorly understood. Here, we tested the evolution of virulence in the human opportunistic pathogen Pseudomonas aeruginosa in a murine chronic wound model using a two-part serial passage and sepsis experiment, and found that virulence evolved in different directions in each line of evolution. We also assessed P. aeruginosa adaptation to a chronic wound after 42 days of evolution, and found that morphological diversity in our evolved populations was limited compared to that previously described in cystic fibrosis (CF) infections. Using whole genome sequencing, we found that genes previously implicated in P. aeruginosa pathogenesis (lasR, pilR, fleQ, rpoN, and pvcA), acquired mutations during the course of evolution in wounds, with some mutations evolving in parallel across all lines of evolution. Our findings highlight that (i) P. aeruginosa heterogeneity may be less extensive in chronic wounds than in CF lungs; (ii) genes involved in P. aeruginosa pathogenesis acquire mutations during chronic wound infection; (iii) similar genetic adaptations are employed by P. aeruginosa across multiple infection environments, and (iv) current models of virulence may not adequately explain the diverging evolutionary trajectories observed in an opportunistic pathogen during chronic wound infection.

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慢性伤口感染过程中铜绿假单胞菌的毒力演变

机会病原体与许多慢性人类感染有关，但人们对慢性感染期间这些生物中毒力的演变仍知之甚少。在这里，我们使用分为两部分的连续传代和败血症实验，在鼠类慢性伤口模型中测试了人类机会病原体铜绿假单胞菌中毒力的演变，并发现在每条进化线中毒力朝不同的方向进化。我们还评估了42天进化后铜绿假单胞菌对慢性伤口的适应性，发现与先前在囊性纤维化（CF）感染中描述的相比，我们进化种群的形态多样性受到限制。使用全基因组测序，我们发现以前与铜绿假单胞菌发病机理有关的基因（lasR，pilR，fleQ，rpoN和pvcA），在伤口进化过程中获得了突变，有些突变在进化的各个方面都在平行发展。我们的发现突出表明：（i）慢性伤口中铜绿假单胞菌的异质性可能不如CF肺大；（ii）与铜绿假单胞菌发病机理有关的基因在慢性伤口感染过程中获得突变；（iii）铜绿假单胞菌在多种感染环境中采用了相似的遗传适应，并且（iv）当前的毒力模型可能不足以解释在慢性伤口感染期间机会病原体中观察到的不同进化轨迹。（ii）与铜绿假单胞菌发病机理有关的基因在慢性伤口感染过程中获得突变；（iii）铜绿假单胞菌在多种感染环境中采用了相似的遗传适应，并且（iv）当前的毒力模型可能不足以解释在慢性伤口感染期间机会病原体中观察到的不同进化轨迹。（ii）铜绿假单胞菌发病机理中涉及的基因在慢性伤口感染期间获得突变；（iii）铜绿假单胞菌在多种感染环境中采用了相似的遗传适应，并且（iv）当前的毒力模型可能不足以解释在慢性伤口感染期间机会病原体中观察到的不同进化轨迹。