title: Optimization of a type III secretion system-based Pseudomonas aeruginosa live vector for antigen delivery.
abstract: During the last few years, the use of type III secretion system-based bacterial vectors for immunotherapy purposes has been assessed in various applications. We showed that a type III secretion-based Pseudomonas aeruginosa vector delivering the ovalbumin (OVA) antigen induced an efficient specific CD8+ T-lymphocyte immune response against OVA-expressing cells. Because of the intrinsic toxicity of the vector, further virulence attenuation was needed. Therefore, we explored the effects of the deletion of quorum-sensing genes and the aroA gene toward toxicity and efficiency of the vector strain. The aroA mutation in our strain (making the strain auxotrophic for aromatic amino acids) conferred a strikingly reduced toxicity, with the bacterial lethal dose being more than 100 times higher than that of the parental strain. The quorum-sensing gene mutation alone was associated with a slightly reduced toxicity. In a prophylactic OVA-expressing melanoma mouse model, an OVA-delivering aroA-deficient mutant was the most efficient at a low dose (10(5)), but dose enhancement was not associated with a greater immune response. The quorum-sensing-deficient strain was the most efficient at a mild dose (10(6)), but this dose was close to the toxic dose. Combination of both mutations conferred the highest efficiency at an elevated dose (10(7)), in agreement with the known negative effects of quorum-sensing molecules upon T-cell activation. In conclusion, we have obtained a promising immunotherapy vector regarding toxicity and efficiency for further developments in both antitumor and anti-infectious strategies.
authors: TIMC-TheREx (UMR5525 CNRS-UJF), Bâtiment Jean Roget, 8th Floor, UFR de Médecine, Université Joseph Fourier Grenoble 1, 38706 La Tronche Cedex, France.
authors: Olivier
authors: O
authors: Epaulard
authors: Madiha
authors: M
authors: Derouazi
authors: Carole
authors: C
authors: Margerit
authors: Raphaël
authors: R
authors: Marlu
authors: Didier
authors: D
authors: Filopon
authors: Benoît
authors: B
authors: Polack
authors: Bertrand
authors: B
authors: Toussaint
mesh_terms: D000818:Animals; D001428:Bacterial Vaccines / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D045744:Cell Line, Tumor; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D017353:Gene Deletion; D005798:Genes, Bacterial / Q000235:genetics*; D007928:Lethal Dose 50; D051379:Mice; D008810:Mice, Inbred C57BL; D010047:Ovalbumin / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D021381:Protein Transport / Q000235:genetics / Q000276:immunology; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000472:pathogenicity*; D053038:Quorum Sensing / Q000235:genetics; D014613:Vaccines, Attenuated / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics
chemical_list: D001428:Bacterial Vaccines; D014613:Vaccines, Attenuated; D037521:Virulence Factors; D010047:Ovalbumin