Summary 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. Highlights ► Microbes co-opt host responses to outcompete other species (IM, immunomodulation) ► IM selects for microbial factors that promote resistance to host responses ► Resistance by colonizing S. pneumoniae to IM correlates with its capsule type ► Virulence traits like capsule type are selected by IM during mucosal competition
Within-Host Competition Drives Selection for the Capsule Virulence Determinant of Streptococcus pneumoniae
숙주 내 경쟁은 폐렴구균의 캡슐 독성 인자를 선택하게 한다
[Category] 폐렴구균 감염증,
[Article Type] Report
[Source] PMC
All Keywords