title: PspK of Streptococcus pneumoniae increases adherence to epithelial cells and enhances nasopharyngeal colonization.
abstract: Streptococcus pneumoniae (the pneumococcus) colonizes the human nasopharynx and can cause invasive disease aided by the pneumococcal capsule. Group II nontypeable S. pneumoniae (NTSp) lacks a polysaccharide capsule, and a subgroup of NTSp carriage isolates has been found to have a novel gene, pneumococcal surface protein K (pspK), which replaces the capsule locus. A recent rise in the number of NTSp isolates colonizing the human nasopharynx has been observed, but the colonization factors of NTSp have not been well studied. PspK has been shown to play a role in mouse colonization. We therefore examined PspK-mediated immune evasion along with adherence to host cells and colonization. PspK bound human secretory immunoglobulin A (sIgA) but not the complement regulator factor H and did not decrease C3b deposition on the pneumococcal surface. PspK increased binding of pneumococci to epithelial cells and enhanced pneumococcal colonization independently of the genetic background. Understanding how NTSp colonizes and survives within the nasopharynx is important due to the increase in NTSp carriage. Our data suggest that PspK may aid in the persistence of NTSp within the nasopharynx but is not involved in invasion.
authors.affiliation: Department of Microbiology, University of Mississippi Medical Center, Jackson, Mississippi, USA.
authors.forename: L E
authors.initials: LE
authors.lastname: Keller
authors.forename: C V
authors.initials: CV
authors.lastname: Jones
authors.forename: J A
authors.initials: JA
authors.lastname: Thornton
authors.forename: M E
authors.initials: ME
authors.lastname: Sanders
authors.forename: E
authors.initials: E
authors.lastname: Swiatlo
authors.forename: M H
authors.initials: MH
authors.lastname: Nahm
authors.forename: I H
authors.initials: IH
authors.lastname: Park
authors.forename: L S
authors.initials: LS
authors.lastname: McDaniel
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000276:immunology / Q000378:metabolism; D001422:Bacterial Adhesion / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D003179:Complement C3b / Q000276:immunology / Q000378:metabolism; D017242:Complement Factor H / Q000276:immunology / Q000378:metabolism; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009305:Nasopharynx / Q000276:immunology / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D013296:Streptococcus pneumoniae / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
chemical_list: D000954:Antigens, Surface; D001426:Bacterial Proteins; D007071:Immunoglobulin A, Secretory; D003179:Complement C3b; D017242:Complement Factor H