184 pages ; Glaesserella parasuis (formerly Haemophilus parasuis) is a significant pathogen in the swine industry, causing Glässer’s disease, characterized by fibrinous polyserositis, arthritis, and meningitis. This disease leads to substantial economic losses due to high morbidity and mortality rates among affected pigs. Effective vaccination is crucial for controlling G. parasuis infections and reducing reliance on antibiotics, which in turn helps mitigate the issue of antimicrobial resistance (AMR).Our research focuses on developing glycoconjugate vaccines to combat G. parasuis infections. Glycoconjugate vaccines, which enhance the immunogenicity of polysaccharide antigens by conjugating them to carrier proteins, have shown great promise in inducing robust immune responses. In this study, we generated a glycoprotein vaccine, PDCPS5, and evaluated its antigenicity. The results demonstrated that PDCPS5 elicited a robust immune response and provided effective protection against G. parasuis in a murine model. Building on the success of the PDCPS5 glycoprotein vaccine, we also developed glycoOMV (glycosylated outer membrane vesicle) vaccines targeting multiple G. parasuis serotypes. Specifically, we created glycoOMV vaccines against serotypes 4, 5, and 14. The individual OMVCPS5 or OMVCPS14 vaccine in preclinical trials displayed sufficient protection against homologous challenge strains. Furthermore, we developed a trivalent vaccine combining OMVCPS4, OMVCPS5, and OMVCPS14, to induce effective cross- protection against all three serotypes. The survival tests for the trivalent vaccine yielded promising results, demonstrating a significant increase in the survival rate of mice challenged with all three serotype strains. These findings suggest that the trivalent vaccine can provide broad-spectrum protection, making it a potent candidate for controlling G. parasuis infections in swine. Our study highlights the potential of glycoconjugate vaccines in providing effective protection against G. parasuis infections. These ...