Identification and characterization of novel immunogenic outer membrane proteins of Haemophilus parasuis serovar 5.

Haemophilus parasuis is the aetiological agent of Glässer's disease, which is responsible for cases of fibrinous polyserositis, polyarthritis and meningitis in young pigs. To develop more effective vaccines, an immunoproteome-based approach was used to analyze the outer membrane proteins of H. parasuis serovar 5. A total of 15 proteins with high immunogenicity were identified and all were showed to be immunogens for the first time in H. parasuis. Further analyses of 8 selected proteins revealed that (1) significantly higher level of serum antibodies against 6 proteins was detected with convalescent sera and immunized sera; (2) antisera against 5 of the selected proteins could effectively inhibit H. parasuis growth in mouse blood; and (3) 4 proteins could induce protective response of the vaccinated mice against H. parasuis. The results suggest these 4 proteins (PalA, Omp2, D15 and HPS_06257) have strong potential to be vaccine candidates.