title: Phenotypic, genomic, and transcriptional characterization of Streptococcus pneumoniae interacting with human pharyngeal cells.
abstract: BACKGROUND
  Streptococcus pneumoniae is a leading cause of childhood morbidity and mortality worldwide, despite the availability of effective pneumococcal vaccines. Understanding the molecular interactions between the bacterium and the host will contribute to the control and prevention of pneumococcal disease.
  
  
  RESULTS
  We used a combination of adherence assays, mutagenesis and functional genomics to identify novel factors involved in adherence. By contrasting these processes in two pneumococcal strains, TIGR4 and G54, we showed that adherence and invasion capacities vary markedly by strain. Electron microscopy showed more adherent bacteria in association with membranous pseudopodia in the TIGR4 strain. Operons for cell wall phosphorylcholine incorporation (lic), manganese transport (psa) and phosphate utilization (phn) were up-regulated in both strains on exposure to epithelial cells. Pneumolysin, pili, stress protection genes (adhC-czcD) and genes of the type II fatty acid synthesis pathway were highly expressed in the naturally more invasive strain, TIGR4. Deletion mutagenesis of five gene regions identified as regulated in this study revealed attenuation in adherence. Most strikingly, ∆SP_1922 which was predicted to contain a B-cell epitope and revealed significant attenuation in adherence, appeared to be expressed as a part of an operon that includes the gene encoding the cytoplasmic pore-forming toxin and vaccine candidate, pneumolysin.
  
  
  CONCLUSIONS
  This work identifies a list of novel potential pneumococcal adherence determinants.
authors.affiliation: Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya.
authors.forename: Sheila Z
authors.initials: SZ
authors.lastname: Kimaro Mlacha
authors.forename: Sandra
authors.initials: S
authors.lastname: Romero-Steiner
authors.forename: Julie C Dunning
authors.initials: JC
authors.lastname: Hotopp
authors.forename: Nikhil
authors.initials: N
authors.lastname: Kumar
authors.forename: Nadeeza
authors.initials: N
authors.lastname: Ishmael
authors.forename: David R
authors.initials: DR
authors.lastname: Riley
authors.forename: Umar
authors.initials: U
authors.lastname: Farooq
authors.forename: Todd H
authors.initials: TH
authors.lastname: Creasy
authors.forename: Luke J
authors.initials: LJ
authors.lastname: Tallon
authors.forename: Xinyue
authors.initials: X
authors.lastname: Liu
authors.forename: Cynthia S
authors.initials: CS
authors.lastname: Goldsmith
authors.forename: Jacquelyn
authors.initials: J
authors.lastname: Sampson
authors.forename: George M
authors.initials: GM
authors.lastname: Carlone
authors.forename: Susan K
authors.initials: SK
authors.lastname: Hollingshead
authors.forename: J Anthony G
authors.initials: JA
authors.lastname: Scott
authors.forename: Hervé
authors.initials: H
authors.lastname: Tettelin
mesh_terms: D001422:Bacterial Adhesion / Q000235:genetics; D045744:Cell Line, Tumor; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D005798:Genes, Bacterial / Q000235:genetics; D023281:Genomics; D006801:Humans; D016296:Mutagenesis; D020411:Oligonucleotide Array Sequence Analysis; D010614:Pharynx / Q000166:cytology* / Q000382:microbiology; D010641:Phenotype; D017384:Sequence Deletion; D013045:Species Specificity; D013296:Streptococcus pneumoniae / Q000235:genetics* / Q000502:physiology*; D014158:Transcription, Genetic / Q000235:genetics*