Vaccine
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Non-typhoid Salmonella (NTS) is a leading cause of food-borne illness with more than 90 million annual cases and an emerging antimicrobial resistance among the strains worldwide. Paradoxically, no vaccines are available against these pathogens. Numerous NTS strains share surface O-antigens with Salmonella enterica serotype Typhi. As intestinal antibodies against O-antigens have proven protective against NTS in animal experiments, it appears conceivable that the oral whole-cell typhoid vaccine, Salmonella Typhi Ty21a (Vivotif(®)), which effectively elicits intestinal antibodies against O-antigens, could exhibit cross-protective efficacy against NTS. We sought immunological evidence in support of cross-protective efficacy of Ty21a against NTS. ⋯ Intestinal antibodies against O-antigens protect against NTS in animal experiments. Ty21a was found to elicit intestinal immune responses cross-reactive with NTS strains sharing O-antigens with Ty21a. These include the most common NTS, Salmonella Enteritidis and Typhimurium. The data suggest that Ty21a may have cross-protective efficacy against numerous NTS strains.