Development of recombinant vaccines composed of PlpE and OmpH from pasteurella multocida A:3

Okay, Sezer
Pasteurella multocida serotype A:3 is a gram-negative bacterial pathogen which is one of the causative agents of shipping fever in cattle. In this study, ompH and two fragments of plpE gene (plpEN and plpEC) were cloned from the genomic DNA of P. multocida P-1062 (ATCC 15743, serotype A:3) and plpEN-ompH and plpEC-ompH fusions were constructed. In vitro expression of the genes was shown in HEK-293 cells. Later, full-length plpE gene was cloned and the recombinant proteins were expressed in E. coli and purified. Three DNA vaccine formulations, namely pCMV-ompH, pCMV-plpEN-ompH and pCMV-plpEC-ompH and five recombinant protein based vaccines, PlpEN-OmpH, PlpEC-OmpH, OmpH, PlpEC and PlpE were generated. Recombinant proteins were formulated with at least one of the adjuvants: alum, CpG, alum-CpG, oil based and oil based-CpG. BALB/c mice were immunized with these vaccine formulations and their sera were used for the evaluation of antibody and serum IFN-γ titers. Protective capacities of the vaccines were also evaluated via challenge of mice with 10 LD50 of P. multocida A:3. DNA vaccines induced immune responses, but did not provide protection. All protein vaccine formulations increased antibody levels and CpG containing formulations enhanced serum IFN-γ titers. 100 µg of PlpEC-OmpH protein adsorbed on alum adjuvant conferred 40% protection while no protection was obtained with PlpEN-OmpH. Next, the effects of CpG, or its alum and oil based combinations as adjuvants were investigated on PlpEC-OmpH mediated protection. The vaccine formulation composed of PlpEC-OmpH and oil based-CpG adjuvant conferred 100% protection. Finally, the mice were vaccinated with recombinant OmpH, PlpEC and PlpE formulated with oil based-CpG adjuvant. OmpH, PlpEC and PlpE formulations provided 50%, 60% and 100% protection, respectively. These findings implicated that recombinant PlpE and PlpEC-OmpH fusion proteins when formulated with oil based-CpG adjuvant are potent acellular vaccine formulation candidates against shipping fever.
Citation Formats
S. Okay, “Development of recombinant vaccines composed of PlpE and OmpH from pasteurella multocida A:3,” Ph.D. - Doctoral Program, Middle East Technical University, 2011.