Dynamic Pneumococcal Genetic Adaptations Support Bacterial Growth and Inflammation during Coinfection with Influenza.
Dynamic Pneumococcal Genetic Adaptations Support Bacterial Growth and Inflammation during Coinfection with Influenza.
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DOI：
10.1128/iai.00023-21
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发表时间：
2021-06-16
影响因子：
3.1
通讯作者：
Smith AM
中科院分区：
文献类型：
--
作者：
Smith AP;Lane LC;van Opijnen T;Woolard S;Carter R;Iverson A;Burnham C;Vogel P;Roeber D;Hochu G;Johnson MDL;McCullers JA;Rosch J;Smith AM
肺炎链球菌（肺炎球菌）是使流感病毒感染复杂化的主要细菌病原体之一。这些细菌合并感染通过许多免疫和病毒介导的机制增加流感相关的发病率和死亡率，但导致流感后致病性的特定细菌基因尚不清楚。在这里，我们使用全基因组转座子诱变（Tn-Seq）来揭示在流感病毒感染的宿主中赋予改进的适应性的细菌基因。所鉴定的32个基因中的大多数参与细菌代谢，包括核苷酸生物合成、氨基酸生物合成、蛋白质翻译和膜转运。我们产生了五个已鉴定基因的单基因缺失（SGD）突变体，SPD 1414，SPD 2047（cbiO 1），SPD 0058（purD），SPD 1098和SPD 0822（proB），以研究它们对体内适应性，疾病严重程度和宿主免疫反应的影响。SGD突变体的生长在体外和体内略有减弱，但每种突变体在模拟病毒和流感病毒感染宿主的肺部仍然生长至高滴度。尽管细菌负荷很高，但所有SGD突变体的死亡率均显着降低或延迟。还观察到肺中性粒细胞、炎性巨噬细胞和选择的促炎细胞因子和趋化因子的时间依赖性减少。免疫组织化学染色进一步揭示了中性粒细胞分布的改变，在流感病毒-SGD病毒共感染动物的肺中变性减少。这些研究证明了特定细菌基因和细菌代谢在流感相关细菌性肺炎期间驱动毒力和调节免疫功能方面的关键作用。
Streptococcus pneumoniae (pneumococcus) is one of the primary bacterial pathogens that complicates influenza virus infections. These bacterial coinfections increase influenza-associated morbidity and mortality through a number of immunological and viral-mediated mechanisms, but the specific bacterial genes that contribute to postinfluenza pathogenicity are not known. Here, we used genome-wide transposon mutagenesis (Tn-Seq) to reveal bacterial genes that confer improved fitness in influenza virus-infected hosts. The majority of the 32 genes identified are involved in bacterial metabolism, including nucleotide biosynthesis, amino acid biosynthesis, protein translation, and membrane transport. We generated mutants with single-gene deletions (SGD) of five of the genes identified, SPD1414, SPD2047 (cbiO1), SPD0058 (purD), SPD1098, and SPD0822 (proB), to investigate their effects on in vivo fitness, disease severity, and host immune responses. The growth of the SGD mutants was slightly attenuated in vitro and in vivo, but each still grew to high titers in the lungs of mock- and influenza virus-infected hosts. Despite high bacterial loads, mortality was significantly reduced or delayed with all SGD mutants. Time-dependent reductions in pulmonary neutrophils, inflammatory macrophages, and select proinflammatory cytokines and chemokines were also observed. Immunohistochemical staining further revealed altered neutrophil distribution with reduced degeneration in the lungs of influenza virus-SGD mutant-coinfected animals. These studies demonstrate a critical role for specific bacterial genes and for bacterial metabolism in driving virulence and modulating immune function during influenza-associated bacterial pneumonia.