Within-Host Competition Drives Selection for the Capsule Virulence Determinant of Streptococcus pneumoniae
Within-Host Competition Drives Selection for the Capsule Virulence Determinant of Streptococcus pneumoniae
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DOI：
10.1016/j.cub.2010.05.051
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发表时间：
2010-07-13
期刊：
影响因子：
9.2
通讯作者：
Weiser, Jeffrey N.
中科院分区：
文献类型：
--
作者：
Lysenko, Elena S.;Lijek, Rebeccah S.;Weiser, Jeffrey N.
对于许多机会致病菌来说，尚不清楚为什么当宿主的损伤或死亡对微生物的生长或生存没有明显的选择优势时，它们的毒力决定因素和致病行为的表达会发生进化[1-3]。许多病原体在粘膜表面开始与宿主相互作用，并且必须与微生物群的其他成员竞争相同的生态位。在这里，我们探讨微生物之间的竞争相互作用是否促进了毒力特征的获得。在模型小鼠鼻腔定植过程中，流感嗜血杆菌通过招募中性粒细胞和刺激杀死补体活化的肺炎球菌[4]，战胜了当地菌群的另一成员肺炎链球菌。对于肺炎链球菌来说，其对调理噬细胞杀伤的耐药性是由其多糖胶囊决定的[5,6]。尽管在不同的肺炎链球菌分离株中存在许多允许有效定植的胶囊类型，但毒性肺炎球菌表达的胶囊赋予抗调理吞噬细胞清除的抵抗力。种间相互作用的模型预测，这些毒性更强的肺炎链球菌将在与流感嗜血杆菌的竞争中胜出，即使胶囊的生产成本很高。实验定植研究证实，在竞争过程中，毒性更强的肺炎链球菌型的存活率增加。我们的研究结果表明，微生物在共生状态下的竞争可能是导致侵袭性疾病的特征选择的基础。
For many opportunistic pathogens, it is unclear why their virulence determinants and expression of pathogenic behavior have evolved when damage or death of their host offers no obvious selective advantage to microbial growth or survival [1-3]. Many pathogens initiate interactions with their host on mucosal surfaces and must compete with other members of the microflora for the same niche. Here we explore whether competitive interactions between microbes promote the acquisition of virulence characteristics. During model murine nasal colonization, Haemophilus influenzae outcompetes another member of the local flora, Streptococcus pneumoniae, by recruiting neutrophils and stimulating the killing of complement-opsonized pneumococci [4]. For S. pneumoniae, resistance to opsonophagocytic killing is determined by its polysaccharide capsule [5, 6]. Although there are many capsule types among different S. pneumoniae isolates that allow for efficient colonization, virulent pneumococci express capsules that confer resistance to opsonophagocytic clearance. Modeling of interspecies interaction predicts that these more virulent S. pneumoniae will prevail during competition with H. influenzae, even if production of a capsule is otherwise costly. Experimental colonization studies confirmed the increased survival of the more virulent S. pneumoniae type during competition. Our findings demonstrate that competition between microbes during their commensal state may underlie selection for characteristics that allow invasive disease.