Rosana B. R. Ferreira, Yanet Valdez, Brian K. Coombes, Subash Sad, Joost W. Gouw, Eric M. Brown, Yuling Li, Guntram A. Grassl, L. Caetano M. Antunes, Navkiran Gill, Mimi Truong, Roland Scholz, Lisa A. Reynolds, Laskshmi Krishnan, Ahmed A. Zafer, Neta Sal-Man, Michael J. Lowden, Sigrid D. Auweter, Leonard J. Foster, and B. Brett Finlay
Nontyphoidal Salmonella enterica (NTS) infections are a major burden to global public health, as they lead to diseases ranging from gastroenteritis to systemic infections and there is currently no vaccine available. Here, we describe a highly effective component vaccine against S. enterica serovar Typhimurium in both gastroenteritis and systemic murine infection models. We devised an approach to generate supernatants of S. enterica serovar Typhimurium, an organism that is highly abundant in virulence factors. Immunization of mice with this supernatant resulted in dramatic protection against a challenge with serovar Typhimurium, showing increased survival in the systemic model and decreased intestinal pathology in the gastrointestinal model. Protection correlated with specific IgA and IgG levels in the serum and specific secretory IgA levels in the feces of immunized mice. Initial characterization of the protective antigens in the bacterial culture supernatants revealed a subset of antigens that exhibited remarkable stability, a highly desirable characteristic of an effective vaccine to be used under suboptimal environmental conditions in developing countries. We were able to purify a subset of the peptides present in the supernatants and show their potential for immunization of mice against serovar Typhimurium resulting in a decreased level of colonization. This component vaccine shows promise with regard to protecting against NTS, and further work should significantly help to establish vaccines against these prevalent infections.
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