RESUMEN
Objective:To analyze the efficiency of delivery for CD8+ T cell epitope by attenuated E.coli vector.Methods:The recombinant E.coli strain 13A(pG2F),harbouring the eukaryotic expression plasmid pG2F with CD8+ T cell epitope of Ovalbumin (OVA) and green fluorescent protein (GFP) marker at the C-terminal was used to infect into LKb cells,bone marrow dendritic cells (BMDC).The efficiency of presentation for CD8+T cell epitope delivered by recombinant bacteria was analyzed by in vitro antigen presentation assay.C57BL/6 mice were immunized intravenously with 13A(pG2F).Murine IFN-? secreting cells were detected in murine splenocytes by enzyme-linked immunospot assay (ELISPOT).Results:After the infection of LKb cells,BMDC by recombinant bacteria,about 0.3%～4% of cells were GFP positive.The results indicated that attenuated strain 13A could deliver the eukaryotic expression plasmid into mammalian cells.At 2 h post infection,CD8+ T cell epitope was presented on the surface of those LKb,BMDC cells infected by 13A (pG2F) could be recognized by B3Z T hybridoma cells.The presentation efficiency of LKb cells for OVA CD8+ T cell epitope was increased at 48h after infection.Furthermore,the presentation efficiency of BMDC was higher than those of LKb cells under the same condition.The recombinant bacteria 13A(pG2F) could induce cellular immune responses in C57BL/6 mice.Conclusion:Attenuated E.coli can effectively deliver the CD8+ T cell epitope in vitro and in vivo.