CONICET | Buscador de Institutos y Recursos Humanos

Non-invasive routes for vaccine delivery are attractive alternatives to classical methods. Bacteria, as cellular vehicles for the administration of antigens and for DNA delivery, are candidates for the development of new vaccines. Nevertheless, most of the bacteria in study are attenuated strains of pathogenic microorganisms. In contrast, food-grade Lactic Acid Bacteria (LAB) are safe candidates as delivery vectors. The efficiency of a DNA vaccine is closely related to the level of expression of the encoded antigen. Thus, our aim was to evaluate two strains of LAB as oral vehicles of a eukaryotic expression vector. The coding sequence of the Enhanced Green Fluorescent Protein (EGFP) was inserted in an E. coli-LAB shuttle plasmid with kanamycin resistance (pLKV1-EGFP). Performance of the plasmid for eukaryotic protein expression was verified by in vitro transfection of cells from the HEK293 line. Lactobacillus paracasei JP1 and Lactococcus lactis Mo12 were transformed with pLKV1-EGFP by electroporation. The plasmid was stable in both LAB strains in the absence of selective pressure: after 20 generations 71% of L. paracasei JP1 cells and 84% of L. lactis Mo12 cells displayed the antibiotic resistance. 108 CFU of each recombinant strain of LAB were orally administered to 5-6 weeks old, Balb/c female mice, every 24 hours for 3 consecutive days. Control animals received no bacteria. Mice were sacrificed 24 hours after the last administration, intestine regions containing Peyer Patches were removed and treated with hyaluronidase. The cell suspension obtained was analyzed by flow cytometry. The reporter protein was detected in animals receiving both transformed bacteria strains, but the percentage of green cells in the analyzed cell population was significantly higher in L. paracasei treated mice (14.6±2.15 vs 1.71±1.76; p

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