AttenuatedSalmonella entericaserovar Typhimurium lacking the ZnuABC transporter: An efficacious orally-administered mucosal vaccine against salmonellosis in pigs

We have recently demonstrated that an attenuated strain ofSalmonella entericaserovar Typhimurium unable to synthesize the zinc transporter ZnuABC (S. TyphimuriumδznuABC), is able to protect mice against systemic and enteric salmonellosis and is safe in pigs. Here, we have tested the protective effects ofS. TyphimuriumδznuABCin pigs. Resistance to challenge with the fully virulent strainS.Typhimurium ATCC 14028 was assessed in animals vaccinated withS. TyphimuriumδznuABC(two dosages tested), in controls vaccinated with a formalin-inactivated virulent strain and in unvaccinated controls. Clinical signs of salmonellosis, faecal shedding and bacterial colonization of organs were used to assess vaccine-induced protection. After the challenge, pigs vaccinated with the attenuatedS.TyphimuriumδznuABCstrain did not display clinical signs of salmonellosis (fever or diarrhoea). The vaccine also reduced intestinal tract colonization and faecal shedding of the fully virulentSalmonellastrain, as compared to control groups.S. TyphimuriumδznuABCrepresents a promising candidate vaccine against salmonellosis in pigs.