Multi-epitope vaccines Xlc and Ddc against Glaesserella parasuis infection in mice

Glaesserella parasuis (synonym Haemophilus parasuis) is the pathogenic agent of Glässer's disease and causes huge economic losses in the world's swine industry. Glaesserella parasuis (G. parasuis) can be divided into 15 serotypes, and the cross-protection effect of existing vaccines is not satisfactory. Therefore, the development of a vaccine to prevent multiple serotypes of G. parasuis infection is of great significance for the prevention and treatment of Glässer's disease, but still faces many difficulties. In this study, the B-cell, CTL and Th cell epitopes of CtdB, CtbC, OppA, TbpB, HxuC, D15, Omp2 and Omp5 proteins were predicted by bioinformatics method, and multi-epitope proteins Xlc and Ddc were obtained by concatenating epitopes through linkers. After immunization with Xlc and Ddc, the levels of antibodies, IL-4, and IFN-γ in mice were significantly increased. The protective rates of Xlc+Ddc immunized mice against G. parasuis serotypes 4, 5, and 10 were 62.5 %, 75 %, and 87.5 %, respectively, which were higher than those of Xlc (37.5 %, 62.5 %, and 87.5 %) and Ddc (75 %, 25 %, and 50 %). Overall, the combination of multi-epitope proteins Xlc and Ddc had good immunogenicity and strong cross-protection against G. parasuis serotypes 4, 5, and 10. These results indicated that multi-epitope proteins Xlc and Ddc can serve as candidate subunit vaccines against G. parasuis infection.