title: Internalin-expressing Lactococcus lactis is able to invade small intestine of guinea pigs and deliver DNA into mammalian epithelial cells.
abstract: The use of the food-grade bacterium Lactococcus lactis as antigen delivery vehicle at the mucosal level is an attractive vaccination strategy intensively explored during the last decade. In this study, we developed L. lactis strains which could be used as a DNA delivery vector to combine both advantages of mucosal delivery and of DNA vaccination. To render lactococci capable of invading epithelial cells, the Listeria monocytogenes inlA gene was cloned and expressed in L. lactis under transcriptional control of the native promoter. Western blot and immunofluorescence assays revealed that recombinant lactococci efficiently displayed the cell wall anchored form of InlA. We demonstrated that this expression promotes internalization of L. lactis inlA+ into the human epithelial cell line Caco-2. Gentamicin assay showed that invasiveness of L. lactis in these cells is approximately 100-fold higher for L. lactis inlA+ than for wild type (wt) L. lactis strains. Moreover, we showed that L. lactis inlA+ is able to enter intestinal cells in vivo, after oral inoculation of guinea pigs. After internalization, L. lactis inlA+ was able to deliver a functional eukaryotic gfp gene into epithelial Caco-2 cells; GFP was detected in 1% of internalized cells. The L. lactis inlA+ strain will be a useful bacterial vector for the development of new live oral DNA vaccines. It also constitutes an interesting new model to study the role of internalin in bacterial localization in the animal host.
authors.affiliation: Unité de Recherches Laitières et de Génétique Appliquée, Institut National de la Recherche Agronomique, Domaine de Vilvert, 78352 Jouy en Josas cedex, France.
authors.forename: Valeria Dellaretti
authors.initials: VD
authors.lastname: Guimarães
authors.forename: Jane Eyre
authors.initials: JE
authors.lastname: Gabriel
authors.forename: François
authors.initials: F
authors.lastname: Lefèvre
authors.forename: Didier
authors.initials: D
authors.lastname: Cabanes
authors.forename: Alexandra
authors.initials: A
authors.lastname: Gruss
authors.forename: Pascale
authors.initials: P
authors.lastname: Cossart
authors.forename: Vasco
authors.initials: V
authors.lastname: Azevedo
authors.forename: Philippe
authors.initials: P
authors.lastname: Langella
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D018938:Caco-2 Cells; D002473:Cell Wall / Q000382:microbiology; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D006168:Guinea Pigs; D006801:Humans; D007421:Intestine, Small / Q000382:microbiology; D013294:Lactococcus lactis / Q000235:genetics* / Q000502:physiology*; D010957:Plasmids
chemical_list: D001426:Bacterial Proteins; C069761:internalin protein, Bacteria