- Oral Salmonella typhimurium (AroA-) vaccine expressing a major leishmanial surface protein (gp63) preferentially induces T helper 1 cells and protective immunity against leishmaniasis. Yang, D.M., Fairweather, N., Button, L.L., McMaster, W.R., Kahl, L.P., Liew, F.Y. J. Immunol. (1990)