title: Influence of VicRK and CovR on the interactions of Streptococcus mutans with phagocytes.
abstract: OBJECTIVE
  Streptococcus mutans are members of the oral microbiota that are implicated in dental caries and infective endocarditis. To adapt to environmental stresses encountered during host colonization, these bacteria employ two-component regulatory systems, which modulate global changes in gene expression. These include the systems VicRK and CovR. In this study, we investigate the influence of VicRK and CovR in S. mutans interactions with mononuclear and polymorphonuclear (PMN) phagocytes.
  
  
  METHODS
  Patterns of S. mutans uptake by murine macrophages were determined in strains, which differ in the production of proteins regulated by VicRK and CovR. Bacterial uptake by murine macrophages and by PMN in human blood was analyzed in vicK and covR knockout mutants obtained in strains UA159 and LT11.
  
  
  RESULTS
  Inactivation of covR did not affect uptake by macrophages, while vicK inactivation transiently reduced uptake only in LT11 (P < 0.05). In the two strains, inactivation of vicK and covR impaired uptake by PMN for a period of 1 h or more (P < 0.01-0.05). Mutant complementation with vicK or covR restored the PMN uptake phenotypes.
  
  
  CONCLUSIONS
  This study indicates that VicRK and CovR regulate functions that influence bacterial susceptibility to phagocytosis, suggesting a novel role for these systems in the virulence of S. mutans.
authors.affiliation: Department of Oral Diagnosis, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil.
authors.forename: T C
authors.initials: TC
authors.lastname: Negrini
authors.forename: C
authors.initials: C
authors.lastname: Duque
authors.forename: N L
authors.initials: NL
authors.lastname: Vizoto
authors.forename: R N
authors.initials: RN
authors.lastname: Stipp
authors.forename: F S
authors.initials: FS
authors.lastname: Mariano
authors.forename: J F
authors.initials: JF
authors.lastname: Höfling
authors.forename: E
authors.initials: E
authors.lastname: Graner
authors.forename: R O
authors.initials: RO
authors.lastname: Mattos-Graner
mesh_terms: D000222:Adaptation, Physiological; D000704:Analysis of Variance; D000818:Animals; D001426:Bacterial Proteins / Q000502:physiology*; D002478:Cells, Cultured; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009504:Neutrophils / Q000382:microbiology; D010586:Phagocytes / Q000382:microbiology*; D013295:Streptococcus mutans / Q000235:genetics / Q000502:physiology*; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D037521:Virulence Factors; C119939:YycF protein, Bacteria