Mucosal vaccination using adjuvant protein vaccines may offer a novel approach for tuberculosis. To date, however, development of such a vaccine has been considered unlikely due to the inability to identify a safe adjuvant that stimulates an appropriate immune response. This study was undertaken to determine the potential of a dairy propionibacteria, P. jensenii strain 702 (PJ702), to act as an adjuvant when co-administered orally with soluble tuberculosis protein to mice. The efficacy of the PJ702 to act as an adjuvant was assessed by comparison with cholera toxin. C57 mice were orally immunized with Mycobacterium tuberculosis short-term culture filtrate protein (STCF) (200 mu g) with either PJ702 (10(8) cfu) or cholera toxin (10 mu) in a total volume of 100 mu L. A control group was given PJ702 108 cfu alone. Each mouse (eight per group) was vaccinated weekly over a 21-day period. At day 25 the mice were sacrificed, spleens were collected and lymphocyte cultures prepared. After stimulation with STCF (2.5 mu g), cell proliferation was measured by H-3 thymidine uptake, and the cytokines, IL-4 and IFN-gamma, by ELISA. A significantly higher T-cell proliferation was observed for the group given the vaccine containing PJ702, compared to both the control group and the group given the vaccine containing cholera toxin (P<0.05). The predominant cytokine produced from all groups was IFN-gamma. These results indicate potential for future development of an oral tuberculosis vaccine, and also identify PJ702 as a potential living vaccine vector that could be applied to a number of mucosally transmitted diseases.