One embodiment provides an attenuated Salmonella strain comprising a lysis gene or cassette operably linked to an intracellularly induced Salmonella promoter. In one embodiment, the promoter is a promoter for one of the genes in Salmonella pathogenicity island 2 type III secretion system (SPI2-T3SS) selected from the group SpiC/SsaB, SseF, SseG, SseI, SseJ, SseK1, SseK2, SifA, SifB, PipB, PipB2, SopD2, GogB, SseL, SteC, SspH1, SspH2, or SirP. In one embodiment, a Salmonella gene is under the regulation of an inducible promoter, wherein the gene is selected from ftsW, ftsA, ftsZ, murE, mukF, imp, secF, eno, hemH, tmk, dxs, uppS, cdsA, accA, pssA, msbA, tsf, trmD, cca, infB, rpoA, rpoB, rpoC, holA, dnaC, or eng. In one embodiment, the Salmonella strain further comprises a plasmid that expresses DNA, shRNA, non-coding RNA and/or a peptide.
