Evaluation of an intracellular-activated promoter for the generation of live Salmonella recombinant vaccines

Salmonella enterica serovar Typhimurium is a versatile host organism for the generation of recombinant live vaccines for mucosal immunization. We investigated the performance of an intracellular-activated promoter for expression of heterologous antigens by Salmonella carrier strains. We observed that intracellular expressed antigens were more efficient in elicitation of humoral and cellular immune responses than constitutively expressed antigens. Furthermore, the intracellular-activated promoter was more efficient in combination with a carrier strain deficient in SPI2 gene sseC than with the conventional aroA strain. We propose that intracellular-activated promoters will be useful tools for construction of efficient recombinant live vaccines.