Expression of heterologous antigens in Salmonella Typhimurium vaccine vectors using the in vivo-inducible, SPI-2 promoter, ssaG

• Published in: Vaccine 2004-09, Vol.22 (25), p.3243-3255
• Main Authors: McKelvie, Nicola D., Stratford, Richard, Wu, Tao, Bellaby, Trevor, Aldred, Emma, Hughes, Nicky J., Chatfield, Steven N., Pickard, Derek, Hale, Christine, Dougan, Gordon, Khan, Shahid A.
• Format: Article
• Language: English
• Subjects: Animals; Antigens, Bacterial - biosynthesis; Antigens, Bacterial - genetics; Antigens, Bacterial - immunology; Bacteriology; Base Sequence; Biological and medical sciences; Cell Survival; Cells, Cultured; Chromosomal expression; Chromosomes, Bacterial - genetics; Chromosomes, Bacterial - immunology; Culture Media; DNA Primers; E. coli heat labile toxin; Escherichia coli; Flow Cytometry; Fundamental and applied biological sciences. Psychology; Genes, Bacterial - genetics; Genes, Bacterial - immunology; Genes, Reporter - genetics; Humans; Immunoglobulin G - biosynthesis; In vivo-inducible expression; Lac Operon - genetics; Macrophages - immunology; Mice; Mice, Inbred BALB C; Microbiology; Microscopy, Confocal; Miscellaneous; Molecular Sequence Data; Plasmids - genetics; Plasmids - immunology; Promoter Regions, Genetic - genetics; Promoter Regions, Genetic - immunology; Reverse Transcriptase Polymerase Chain Reaction; S. Typhimurium; Salmonella enterica; Salmonella Pathogenicity Island-2; Salmonella typhimurium; Salmonella typhimurium - genetics; Salmonella typhimurium - immunology; Salmonella Vaccines - genetics; Salmonella Vaccines - immunology; ssaG promoter; Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies; Vaccines, DNA - biosynthesis; Vaccines, DNA - immunology
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2004.05.014

DNA derived from regions upstream of the Salmonella enterica serovar Typhimurium ssaG gene were used to drive expression of different reporter genes in putative Salmonella vaccine strains. Expression from ssaG was shown to be significantly upregulated once Salmonella had entered murine or human macrophages, and levels of expression were dependent on the length of the ssaG 5′ sequence incorporated. S. Typhimurium derivatives harbouring the Escherichia coli heat labile toxin B subunit (LT-B) fused to various lengths of the ssaG promoter region were also constructed as single copy chromosomal integrations. Expression of LT-B by these Salmonella derivatives was detected at significant levels after intra-macrophage survival and mice immunised with these derivatives mounted marked anti-LT-B humoral antibody responses.