title: Involvement of antigen I/II surface proteins in Streptococcus mutans and Streptococcus intermedius biofilm formation.
abstract: OBJECTIVE
  Dental diseases are caused by microorganisms organized in biofilms. Streptococcus mutans and Streptococcus intermedius are commensals of the human oral cavity. S. mutans is associated with caries, whereas S. intermedius is associated with purulent infections. Oral streptococci including S. mutants and S. intermedius express a family of surface proteins termed antigen I/II (Ag I/II). Ag I/II is implicated in adhesion; however, its role in biofilm formation has not yet been investigated.
  
  
  METHODS
  By using isogenic Ag I/II-deficient mutants of S. mutans and S. intermedius we studied the influence of Ag I/II on in vitro biofilm formation. Biofilm was quantified in polystyrene microtiter plates and visualized by scanning electron microscopy. Ag I/II expression in planktonic and biofilm cells, as well as in the presence or absence of saliva was investigated by immunoblotting.
  
  
  RESULTS
  In the presence of saliva, the Ag I/II-deficient mutants formed 65% less biofilm than the wild-types. In the absence of saliva, no difference was observed in S. mutans, whereas the S. intermedius Ag I/II mutant formed 41% less biofilm. Ag I/II expression was reduced in the presence of saliva. No differences in expression were observed between biofilm and planktonic cells.
  
  
  CONCLUSIONS
  The results indicated that Ag I/II may be important during biofilm formation particularly in the presence of saliva. These findings may provide useful information regarding the importance of Ag I/II in biofilm formation and in the search of new strategies to control biofilm-mediated infections.
authors.affiliation: Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway. ddasilva@odont.uio.no
authors.forename: D
authors.initials: D
authors.lastname: Pecharki
authors.forename: F C
authors.initials: FC
authors.lastname: Petersen
authors.forename: S
authors.initials: S
authors.lastname: Assev
authors.forename: A A
authors.initials: AA
authors.lastname: Scheie
mesh_terms: D001422:Bacterial Adhesion / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development*; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D009055:Mouth / Q000382:microbiology; D009154:Mutation / Q000235:genetics; D012463:Saliva / Q000502:physiology; D034367:Streptococcus intermedius / Q000235:genetics / Q000502:physiology*; D013295:Streptococcus mutans / Q000235:genetics / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D008562:Membrane Glycoproteins; C055764:S-layer proteins