Salmonella Typhimurium lacking the Znuabc transporter is attenuated and immunogenic in pigs

Abstract

Meat contamination by Salmonella spp. is emerging as a major cause of human enteric infections in industrialized countries. The attempts to reduce human cases of salmonellosis encompass pre- and post-harvest interventions. In this context, vaccination of pigs may represent an effective instrument in eliminating/reducing Salmonella burden through the food chain. We have previously demonstrated that Salmonella Typhimurium lacking the ZnuABC transporter (. S. Typhimurium δ. znuABC) is a promising candidate live vaccine in different mouse models of Salmonella Typhimurium infection. In this study, we confirmed in pigs the attenuation of S. Typhimurium δ. znuABC. Moreover, we evaluated the safety and immunogenicity of S. Typhimurium δ. znuABC administered to pigs by the oral route. We monitored clinical conditions of animals and we conducted a microbiological culture and a quantification of the humoral and cellular immune response, respectively, on fecal and blood samples of pigs. After vaccination with attenuated S. Typhimurium δ. znuABC, pigs showed a modest degree of hyperthermia. In addition, fecal shedding of S. Typhimurium δ. znuABC could not be detected 28 days after the inoculum. Furthermore, vaccination with S. Typhimurium δz. nuABC elicited a distinct production of anti-. Salmonella antibodies and IFN-γ. Taken together, these results suggest that S. Typhimurium δ. znuABC is attenuated and immunogenic in pigs. Although the vaccine dosages do not guarantee complete safety there is ample margin to set up better conditions of use, suggesting that S. Typhimurium δ. znuABC could be a promising attenuated strain to be used as live mucosal vaccine for oral delivery. © 2013 Elsevier Ltd.