title: Heterologous expression of pathogen-specific genes ligA and ligB in the saprophyte Leptospira biflexa confers enhanced adhesion to cultured cells and fibronectin.
abstract: BACKGROUND
  In comparison to other bacterial pathogens, our knowledge of the molecular basis of the pathogenesis of leptospirosis is extremely limited. An improved understanding of leptospiral pathogenetic mechanisms requires reliable tools for functional genetic analysis. Leptospiral immunoglobulin-like (Lig) proteins are surface proteins found in pathogenic Leptospira, but not in saprophytes. Here, we describe a system for heterologous expression of the Leptospira interrogans genes ligA and ligB in the saprophyte Leptospira biflexa serovar Patoc.
  
  
  RESULTS
  The genes encoding LigA and LigB under the control of a constitutive spirochaetal promoter were inserted into the L. biflexa replicative plasmid. We were able to demonstrate expression and surface localization of LigA and LigB in L. biflexa. We found that the expression of the lig genes significantly enhanced the ability of transformed L. biflexa to adhere in vitro to extracellular matrix components and cultured cells, suggesting the involvement of Lig proteins in cell adhesion.
  
  
  CONCLUSIONS
  This work reports a complete description of the system we have developed for heterologous expression of pathogen-specific proteins in the saprophytic L. biflexa. We show that expression of LigA and LigB proteins from the pathogen confers a virulence-associated phenotype on L. biflexa, namely adhesion to eukaryotic cells and fibronectin in vitro. This study indicates that L. biflexa can serve as a surrogate host to characterize the role of key virulence factors of the causative agent of leptospirosis.
authors.affiliation: Institut Pasteur, Unité de Biologie des Spirochètes, Paris Cedex 15, France. mpicard@pasteur.fr
authors.forename: Cláudio Pereira
authors.initials: CP
authors.lastname: Figueira
authors.forename: Julio
authors.initials: J
authors.lastname: Croda
authors.forename: Henry A
authors.initials: HA
authors.lastname: Choy
authors.forename: David A
authors.initials: DA
authors.lastname: Haake
authors.forename: Mitermayer G
authors.initials: MG
authors.lastname: Reis
authors.forename: Albert I
authors.initials: AI
authors.lastname: Ko
authors.forename: Mathieu
authors.initials: M
authors.lastname: Picardeau
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism*; D001422:Bacterial Adhesion; D002460:Cell Line; D004285:Dogs; D004847:Epithelial Cells / Q000382:microbiology*; D005353:Fibronectins / Q000378:metabolism*; D015870:Gene Expression; D005822:Genetic Vectors; D007919:Leptospira / Q000235:genetics / Q000472:pathogenicity*; D010957:Plasmids; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000942:Antigens, Bacterial; D005353:Fibronectins; C487005:LigA-m protein, Leptospira interrogans; C487006:LigB-m protein, Leptospira interrogans; D011994:Recombinant Proteins; D037521:Virulence Factors