- An attenuated aroA Salmonella typhimurium vaccine elicits humoral and cellular immunity to cloned beta-galactosidase in mice. Brown, A., Hormaeche, C.E., Demarco de Hormaeche, R., Winther, M., Dougan, G., Maskell, D.J., Stocker, B.A. J. Infect. Dis. (1987)