Application of an -Linked Glycosylation System in Serotype O:9 to Generate a New Candidate Vaccine against .

Brucellosis is a major zoonotic public health threat worldwide, causing veterinary morbidity and major economic losses in endemic regions. However, no efficacious brucellosis vaccine is yet available, and live attenuated vaccines commonly used in animals can cause human infection. - and -linked glycosylation systems have been successfully developed and exploited for the production of successful bioconjugate vaccines. Here, we applied an -linked glycosylation system to a low-pathogenicity bacterium, serotype O:9 ( O:9), which has repeating units of O-antigen polysaccharide (OPS) identical to that of (), to develop a bioconjugate vaccine against . The glycoprotein we produced was recognized by both anti- and anti- O:9 monoclonal antibodies. Three doses of bioconjugate vaccine-elicited OPS-specific serum IgG in mice, significantly reducing bacterial loads in the spleen following infection with the hypovirulent smooth strain A19. This candidate vaccine mitigated infection and prevented severe tissue damage, thereby protecting against lethal challenge with A19. Overall, the results indicated that the bioconjugate vaccine elicited a strong immune response and provided significant protection against brucellosis. The described vaccine preparation strategy is safe and avoids large-scale culture of the highly pathogenic .