An alternative strategy would entail the transfer of a core set of virulence genes from pathogenic Lm to create a strain that is attenuated for virulence but is capable of inducing an effective immune response. To explore this approach we have transferred the vgc locus of Lm into a non-pathogenic species of Listeria such as L. innocua (L.inn) as a carrier strain. Here we show that a single immunization with this recombinant strain (L.inn::vgc) fulfills the desired requirements for a successful bacterial vaccine vector. These include low virulence in association with induction of protective antigen-specific CD8 + T-cell responses and reduction of CD4 + T cell-mediated inflammation.