title: Pattern of accessory regions and invasive disease potential in Streptococcus pneumoniae.
abstract: BACKGROUND
  The invasive disease potential (IDP) of Streptococcus pneumoniae differs between serotypes, but the reason for this is unknown.
  
  
  METHODS
  A total of 47 pneumococcal isolates from 13 serotypes with different IDPs in humans that belonged to 37 multilocus sequence types were compared by whole genome microarrays and mutant analyses.
  
  
  RESULTS
  Approximately 34% of the genes were variable, including 95 genes previously shown by signature-tagged mutagenesis (STM) to be required for invasive disease in mice. Many variable genes were localized to 41 accessory regions (ARs), of which 24 contained genes previously identified by STM as required for invasive disease. Only AR6 and AR34 were preferentially found in isolates of serotypes with high IDPs. Neither AR6, which carries a gene previously identified bySTMas required for invasive disease and encodes a 6-phospho-betaglucosidase, nor the putative adhesin expressed by AR34 was required for mouse virulence in TIGR4.
  
  
  CONCLUSIONS
  Pneumococci possess a repertoire of ARs that differ between clones and even between isolates of the same clone. The ARs required for invasive disease in humans may be redundant, as no unique pattern distinguished the most invasive clones from others. The ARs that contained genes previously identified by STM as required for virulence in mice were frequently absent from invasive human isolates. Only 1 AR (AR6) was present in almost all isolates from the serotypes with the highest IDP (1, 4, and 7F), whereas it was missing from many others.
authors.affiliation: Swedish Institute for Infectious Disease Control, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Blomberg
authors.forename: J
authors.initials: J
authors.lastname: Dagerhamn
authors.forename: S
authors.initials: S
authors.lastname: Dahlberg
authors.forename: S
authors.initials: S
authors.lastname: Browall
authors.forename: J
authors.initials: J
authors.lastname: Fernebro
authors.forename: B
authors.initials: B
authors.lastname: Albiger
authors.forename: E
authors.initials: E
authors.lastname: Morfeldt
authors.forename: S
authors.initials: S
authors.lastname: Normark
authors.forename: B
authors.initials: B
authors.lastname: Henriques-Normark
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D016680:Genome, Bacterial; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D011008:Pneumococcal Infections / Q000382:microbiology*; D040081:Protein Array Analysis; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000235:genetics / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins