DIFFERENTIAL INDUCTION OF CARRIER ANTIGEN-SPECIFIC IMMUNITY BY SALMONELLA-TYPHIMURIUM LIVE-VACCINE STRAINS AFTER SINGLE MUCOSAL OR INTRAVENOUS IMMUNIZATION OF BALB C MICE/

In this study, we constructed strain KR21 (chi 4550 Delta cya Delta cr p Delta asd/pYA292asd(+)-toxC(+)) and compared it with BRD847 (aroA ar oD/pnirB-toxC) for the ability to induce humoral and cellular immunity after a single oral or intravenous immunization in 3- to 4-week-old B ALB/c mice. ToxC-specific serum immunoglobulin G (IgG) was detectable in animals orally immunized with either BRD847 or KR21. However, after intravenous immunization, IgG was detected only in BRD847-immunized a nimals. Measurement of immunoglobin types IgG1 and IgG2a suggests that a Th1 cellular response is prominent after immunizations with either system. ToxC-specific IgA was detected in fecal and vaginal samples of animals immunized orally and intravenously with BRD847, while those i mmunized with KR21 failed to show fecal or vaginal IgA responses. Dela yed-type hypersensitivity was used as a measure of induction of T-cell responses in vivo. Mice immunized either orally or intravenously with BRD847 showed significant ear swelling responses after ToxC injection s, while KR21-immunized animals failed to show a cellular response. Th ese data indicate that the aroA aroD/pnirB system holds greater potent ial for inducing global immunity after a single dose when directly com pared with the balanced lethal system (Delta cya Delta crp Delta asd/p YA29asd(+)).