title: Overexpression of Enterococcus faecalis elr operon protects from phagocytosis.
abstract: BACKGROUND
  Mechanisms underlying the transition from commensalism to virulence in Enterococcus faecalis are not fully understood. We previously identified the enterococcal leucine-rich protein A (ElrA) as a virulence factor of E. faecalis. The elrA gene is part of an operon that comprises four other ORFs encoding putative surface proteins of unknown function.
  
  
  RESULTS
  In this work, we compared the susceptibility to phagocytosis of three E. faecalis strains, including a wild-type (WT), a ΔelrA strain, and a strain overexpressing the whole elr operon in order to understand the role of this operon in E. faecalis virulence. While both WT and ΔelrA strains were efficiently phagocytized by RAW 264.7 mouse macrophages, the elr operon-overexpressing strain showed a decreased capability to be internalized by the phagocytic cells. Consistently, the strain overexpressing elr operon was less adherent to macrophages than the WT strain, suggesting that overexpression of the elr operon could confer E. faecalis with additional anti-adhesion properties. In addition, increased virulence of the elr operon-overexpressing strain was shown in a mouse peritonitis model.
  
  
  CONCLUSIONS
  Altogether, our results indicate that overexpression of the elr operon facilitates the E. faecalis escape from host immune defenses.
authors.affiliation: INRA, UMR1319 Micalis, Jouy-en-Josas, France. naima.cortes-perez@jouy.inra.fr.|AgroParisTech, UMR1319 Micalis, Jouy-en-Josas, France. naima.cortes-perez@jouy.inra.fr.|Current address: INRA, Unité d'Immuno-Allergie Alimentaire, iBiTecS/SPI, Gif-sur-Yvette, France. naima.cortes-perez@jouy.inra.fr.
authors.forename: Naima G
authors.initials: NG
authors.lastname: Cortes-Perez
authors.affiliation: INRA, UMR1319 Micalis, Jouy-en-Josas, France. rom.dumoulin@gmail.com.|AgroParisTech, UMR1319 Micalis, Jouy-en-Josas, France. rom.dumoulin@gmail.com.
authors.forename: Romain
authors.initials: R
authors.lastname: Dumoulin
authors.affiliation: INRA, UMR1319 Micalis, Jouy-en-Josas, France. stephane.gaubert@jouy.inra.fr.|AgroParisTech, UMR1319 Micalis, Jouy-en-Josas, France. stephane.gaubert@jouy.inra.fr.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Gaubert
authors.affiliation: INRA, UMR1319 Micalis, Jouy-en-Josas, France. caroline.lacoux@jouy.inra.fr.|AgroParisTech, UMR1319 Micalis, Jouy-en-Josas, France. caroline.lacoux@jouy.inra.fr.
authors.forename: Caroline
authors.initials: C
authors.lastname: Lacoux
authors.affiliation: Institute of Microbiology, Università Cattolica del Sacro Cuore, Rome, Italy. francesca.bugli@rm.unicatt.it.
authors.forename: Francesca
authors.initials: F
authors.lastname: Bugli
authors.affiliation: INRA, UMR1319 Micalis, Jouy-en-Josas, France. rebeca.martinrosique@jouy.inra.fr.|AgroParisTech, UMR1319 Micalis, Jouy-en-Josas, France. rebeca.martinrosique@jouy.inra.fr.
authors.forename: Rebeca
authors.initials: R
authors.lastname: Martin
authors.affiliation: INRA, UMR1319 Micalis, Jouy-en-Josas, France. sophie.chat@jouy.inra.fr.|AgroParisTech, UMR1319 Micalis, Jouy-en-Josas, France. sophie.chat@jouy.inra.fr.
authors.forename: Sophie
authors.initials: S
authors.lastname: Chat
authors.affiliation: INRA, UMR1319 Micalis, Jouy-en-Josas, France. kevin.piquand@gmail.com.|AgroParisTech, UMR1319 Micalis, Jouy-en-Josas, France. kevin.piquand@gmail.com.
authors.forename: Kevin
authors.initials: K
authors.lastname: Piquand
authors.affiliation: INRA, UMR1319 Micalis, Jouy-en-Josas, France. thierry.meylheuc@jouy.inra.fr.|AgroParisTech, UMR1319 Micalis, Jouy-en-Josas, France. thierry.meylheuc@jouy.inra.fr.
authors.forename: Thierry
authors.initials: T
authors.lastname: Meylheuc
authors.affiliation: INRA, UMR1319 Micalis, Jouy-en-Josas, France. philippe.langella@jouy.inra.fr.|AgroParisTech, UMR1319 Micalis, Jouy-en-Josas, France. philippe.langella@jouy.inra.fr.
authors.forename: Philippe
authors.initials: P
authors.lastname: Langella
authors.affiliation: Institute of Microbiology, Università Cattolica del Sacro Cuore, Rome, Italy. msanguinetti@rm.unicatt.it.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Sanguinetti
authors.affiliation: Institute of Public Health (Section of Hygiene), Università Cattolica del Sacro Cuore, Rome, Italy. bposteraro@rm.unicatt.it.
authors.forename: Brunella
authors.initials: B
authors.lastname: Posteraro
authors.affiliation: INRA, UMR1319 Micalis, Jouy-en-Josas, France. lionel.rigottier-gois@jouy.inra.fr.|AgroParisTech, UMR1319 Micalis, Jouy-en-Josas, France. lionel.rigottier-gois@jouy.inra.fr.
authors.forename: Lionel
authors.initials: L
authors.lastname: Rigottier-Gois
authors.affiliation: INRA, UMR1319 Micalis, Jouy-en-Josas, France. pascale.serror@jouy.inra.fr.|AgroParisTech, UMR1319 Micalis, Jouy-en-Josas, France. pascale.serror@jouy.inra.fr.
authors.forename: Pascale
authors.initials: P
authors.lastname: Serror
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D004195:Disease Models, Animal; D013293:Enterococcus faecalis / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology / Q000662:veterinary; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D009876:Operon; D010538:Peritonitis / Q000382:microbiology*; D010587:Phagocytosis; D014774:Virulence
chemical_list: D001426:Bacterial Proteins