Patent ID: 6936425

Claim:
A carrier for the presentation of an antigen to a host which is an attenuated gram-negative cell comprising the SP12 gene locus, wherein at least one of the effector genes selected from the group consisting of sseA, sseC, sseD, sseE, sseF and sseG is inactivated; and/or wherein the chaperon gene sscB is inactivated; and/or wherein at least one of the secretion apparatus genes selected from the group consisting of ssaE, ssaG and ssaH is inactivated; and wherein said inactivation results in an attenuation/reduction of virulence compared to the wild type of said cells, and wherein said cell comprises at least one heterologous nucleic acid molecule comprising a nucleic acid sequence coding for said antigen, wherein said cell is capable of expressing said nucleic acid molecule or capable of causing the expression of said nucleic acid molecule in a target cell.