title: Oral delivery of a DNA vaccine against tuberculosis using operator-repressor titration in a Salmonella enterica vector.
abstract: Attenuated Salmonella enterica offers a vaccine delivery route that has the benefits of enhanced immunogenicity and oral delivery. The majority of immunization studies have been conducted to deliver recombinant proteins, expressed from a gene that is either chromosomally integrated or carried on a low- or medium-copy number plasmid. There are, however, an increasing number of reports demonstrating the delivery of DNA vaccines, but the high-copy number plasmids that are preferentially used for this application are unstable in Salmonella. Here, we use the Operator-Repressor Titration (ORT) plasmid maintenance system in Salmonella enterica serovar Typhimurium to deliver a high-copy number plasmid expressing the Mycobacterium tuberculosis gene mpt64 to mice. MPT64 expression was detected in phagocytes using immunofluorescence microscopy following Salmonella-mediated delivery of the DNA vaccine. The indicative CD8+ responses measured by antigen-specific IFN-γ were higher from the live bacterial vector than from injected plasmid DNA, and a reduction in the pulmonary bacterial load was seen following an aerogenic challenge. This illustrates the potential of live attenuated Salmonella as oral tuberculosis vaccine vectors.
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK.
authors.forename: Jen-Min
authors.initials: JM
authors.lastname: Huang
authors.forename: Michela
authors.initials: M
authors.lastname: Sali
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Leckenby
authors.forename: David S
authors.initials: DS
authors.lastname: Radford
authors.forename: Hong A
authors.initials: HA
authors.lastname: Huynh
authors.forename: Giovanni
authors.initials: G
authors.lastname: Delogu
authors.forename: Rocky M
authors.initials: RM
authors.lastname: Cranenburgh
authors.forename: Simon M
authors.initials: SM
authors.lastname: Cutting
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D058491:Bacterial Load; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002460:Cell Line; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D005260:Female; D005822:Genetic Vectors; D007111:Immunity, Cellular; D007371:Interferon-gamma / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010586:Phagocytes / Q000276:immunology; D010957:Plasmids / Q000276:immunology; D019779:Salmonella enterica / Q000276:immunology; D014376:Tuberculosis / Q000276:immunology / Q000517:prevention & control*; D032581:Tuberculosis Vaccines / Q000008:administration & dosage / Q000276:immunology*; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology*
chemical_list: D000942:Antigens, Bacterial; D018984:Epitopes, T-Lymphocyte; C510537:MPT64 protein, Mycobacterium tuberculosis; D032581:Tuberculosis Vaccines; D014613:Vaccines, Attenuated; D019444:Vaccines, DNA; D007371:Interferon-gamma