title: A new plasmid vector for DNA delivery using lactococci.
abstract: BACKGROUND
  The use of food-grade lactococci as bacterial carriers to DNA delivery into epithelial cells is a new strategy to develop live oral DNA vaccine. Our goal was to develop a new plasmid, named pValac, for antigen delivery for use in lactococci. The pValac plasmid was constructed by the fusion of: i) a eukaryotic region, allowing the cloning of an antigen of interest under the control of the pCMV eukaryotic promoter to be expressed by a host cell and ii) a prokaryotic region allowing replication and selection of bacteria. In order to evaluate pValac functionality, the gfp ORF was cloned into pValac (pValac:gfp) and was analysed by transfection in PK15 cells. The applicability of pValac was demonstrated by invasiveness assays of Lactococcus lactis inlA+ strains harbouring pValac:gfp into Caco-2 cells.
  
  
  RESULTS
  After transfection with pValac:gfp, we observed GFP expression in PK15 cells. L. lactis inlA+ were able to invade Caco-2 cells and delivered a functional expression cassette (pCMV:gfp) into epithelial cells.
  
  
  CONCLUSIONS
  We showed the potential of an invasive L. lactis harbouring pValac to DNA delivery and subsequent triggering DNA expression by epithelial cells. Further work will be to examine whether these strains are able to deliver DNA in intestinal cells in vivo.
authors.affiliation: Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB-UFMG), Belo Horizonte - MG, Brasil. valeria.guimaraes@cea.fr
authors.forename: Valeria
authors.initials: V
authors.lastname: Guimarães
authors.forename: Sylvia
authors.initials: S
authors.lastname: Innocentin
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Chatel
authors.forename: François
authors.initials: F
authors.lastname: Lefèvre
authors.forename: Philippe
authors.initials: P
authors.lastname: Langella
authors.forename: Vasco
authors.initials: V
authors.lastname: Azevedo
authors.forename: Anderson
authors.initials: A
authors.lastname: Miyoshi