An attenuated Salmonella-vectored vaccine elicits protective immunity against Mycobacterium tuberculosis

There is a need to develop protective vaccines against tuberculosis (TB) that elicit full immune responses including mucosal immunity. Here, a live attenuated Salmonellatyphimurium aroA SL7207 vector TB vaccine, namely SL(E6-85B), harboring the Mycobacterium tuberculosis (M. tb) H37Rv ESAT6-Ag85B fusion gene was developed. The experimental data demonstrated that this SL(E6-85B) vaccine, or when it is combined with BCG vaccination, induced the strongest TB Ag-specific mucosal, humoral, and cellular immune responses comprised of increased proliferation of T cells, IFN-gamma expression, granzyme B production, as well as the greatest IFN-gamma production of effector-memory T (T(EM)) or effector CD8(+) T cell responses and exerted high protective efficacy in mice against virulent M. tb H37Rv challenge compared to the other vaccinated groups (mice immunized with SL(Ag85B), a DNA vaccine or BCG only). This strategy may represent a novel promising mucosal vaccine candidate for the prevention of TB which are inexpensive to produce, efficacious, and able to be given orally rather than by injection.