Work

Bi-valent polysaccharides of Vi capsular and O9 O-antigen in attenuated Salmonella Typhimurium induce strong immune responses against these two antigens

Year: 2018

Type: article

Abstract: SalmonellaTyphi is the causative agent of typhoid fever in humans, responsible for approximately 21 million infections and 222,000 deaths globally each year. The current licensed vaccines provide moderate protection to recipients aged >2 years. Prior work on typhoid vaccines has focused on injectable Vi capsular polysaccharide or Vi–protein conjugates and live, oral attenuatedS. Typhi vaccines to induce humoral anti-Vi antibodies, while the value and importance of anti-O9 antibodies is less well established. In this study, we constructed aS. Typhimurium strain that synthesizes Vi capsular antigen in vivo and produces the immunodominant O9-antigen polysaccharide instead of its native O4-antigen. The live recombinant attenuatedS. Typhimurium mutants were effective in stimulating anti-Vi and anti-O9 antibodies in a mouse model, and the surface Vi capsular expression did not affect the immune responses against the O9 O-antigen polysaccharide. Moreover, the resulting anti-Vi and anti-O9 antibodies were effective at killingS. Typhi and otherSalmonellaspp. expressing Vi or O9 antigen polysaccharides and provided efficient protection against lethal challenge byS. Typhimurium andS. Enteritidis. Our work highlights the strategy of developing live attenuatedS. Typhimurium vaccines to prevent typhoid fever by targeting the both Vi capsular and O9 O-polysaccharide antigens simultaneously.

Source: npj Vaccines

DOI: 10.1038/s41541-017-0041-5