A Core Glycolipid Vaccine Elicits Cross-reactive Antibodies Against Salmonella Species and Protects Against Invasive Nontyphoidal Salmonella Disease in Mice.

Abstract

BACKGROUND: Enteric fever caused by Salmonella enterica serovars Typhi and Paratyphi A in addition to gastroenteritis and invasive disease, predominantly attributable to nontyphoidal Salmonella serovars Typhimurium and Enteritidis, are major causes of death and disability across the globe. A broad-spectrum vaccine that protects against disease caused by typhoidal and nontyphoidal serovars of Salmonella is not available for humans but would prevent a considerable burden of disease worldwide. METHODS: We previously developed a broad-spectrum vaccine for gram-negative bacteria that is based on the inner core domain of detoxified Escherichia coli O111, Rc (J5) mutant lipooligosaccharide, a highly conserved antigen across gram-negative bacteria, complexed with an outer membrane protein of group B Neisseria meningitidis. In this study, mice and rabbits were immunized with the J5 core/outer membrane protein subunit vaccine. We assessed the cross-reactivity of antisera with various Salmonella species lipopolysaccharides and the protective efficacy of passive and active immunization with J5 vaccine against experimental nontyphoidal Salmonella infection in mice. RESULTS: Vaccination with J5 induced IgG responses that strongly recognized lipopolysaccharide from both typhoidal and nontyphoidal Salmonella and imparted a survival benefit against lethal heterologous challenges with S. Typhimurium and S. Enteritidis. Additionally, passive transfer studies with rabbit hyperimmune sera raised against the J5 vaccine revealed that anti-core antibodies were protective against lipopolysaccharide challenge in D-galactosamine-sensitized mice. CONCLUSIONS: Our findings support the development of core glycolipids as a novel Salmonella vaccine candidate. Further investigation is warranted to determine the efficacy of the J5 core/outer membrane protein vaccine against other Salmonella serovars of concern.