Patent ID: 8318148

Claim:
A composition which: (a) induces an immune response to colonization factor CFA/I, and comprises a bacterial cell which expresses colonization factor antigen CFA/I from a native plasmid but does not express heat stable toxin (ST)or (b) induces an immune response to colonization factor CS5 and/or colonization factor CS6, and comprises a bacterial cell which expresses colonization factor antigen CS5 from a native plasmid and/or expresses colonization factor antigen CS6 from a native plasmid but does not express heat stable toxin (ST); wherein the cell is attenuated by deletion or inactivation of one or more gene(s) selected from the group consisting of aroA, aroC, aroD, aroE, pur, htrA, ompC, ompF, ompR, cya, crp, phoP, surA, rfaY, dksA, hupA, sipC and cIpB.