A fusogenic peptide expressed on the surface ofSalmonella entericaelicits CTL responses to a dengue virus epitope

• Published in: Vaccine 2007-06, Vol.25 (27), p.5071
• Main Authors: Luria-Perez, R, Cedillo-Barron, L, Santos-Argumedo, L, Ortiz-Navarrete, VF, Ocaña-Mondragon, A, Gonzalez-Bonilla, CR
• Format: Article
• Language: English
• Subjects: Amino acids; Bacteriology; Dengue fever; Plasmids; Salmonella; Vector-borne diseases
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2007.03.047

AttenuatedSalmonellastrains are used widely as live carriers of antigens because they elicit both mucosal and systemic immunity against passenger antigens. However, they generally evoke poor cytotoxic T cell (CTL) responses becauseSalmonellaresides within vacuolar compartments and the passenger antigens must travel to the cytosol and be processed through the MHC class I-dependent pathway to simulate CTLs. To address this problem, we designed a fusion protein to destabilize the phagosome membrane and allow a dengue epitope to reach the cytosol. The fusion protein was displayed on the bacterial surface ofSalmonella entericaserovar Typhimurium SL3261 through the β domain of the autotransporter MisL. The passenger α domain contained, from the N-terminus, a fusogenic sequence, the NS3 protein 298-306-amino acid CTL epitope from the dengue virus type 2, a molecular tag, and a recognition site for the protease OmpT to release it to the milieu. Display of the fusion protein on the bacterial surface was demonstrated by IFA and flow cytometry using antibodies against the molecular tag. Cleavage of the fusogenic protein-dengue peptide was demonstrated by flow cytometry using OmpT+Escherichia colistrains. The recombinantSalmonellastrains displaying the fusogenic-dengue peptide were able to lyse erythrocytes, induced specific proliferative responses, and elicited CTL responses. These results suggest that the recombinant fusion proteins containing fusogenic sequences provide a promising system to induce CTLs by live vector vaccines.