Comparison of the Effect of Two Purification Methods on the Immunogenicity of Recombinant Outer Membrane Protein H of Pasteurella multocida

Recombinant outer membrane protein H (rOmpH) of Pasteurella multocida strain X-73 can be purified using affinity chromatography but this adversely affects its immunogenicity. The current study presents the results from an intervention study comparing the immunogenicity of rOmpH purified using electroelution with rOmpH purified using affinity chromatography and native OmpH purified using electroelution and a nonimmunized control group. Chickens immunized with rOmpH purified using electroelution produced the highest ELISA antibody levels against P. multocida strains. Chickens in each of the 5 treatment groups were split into two subgroups for challenge with two different P. multocida strains. The average number of adhesions to CEF cells was statistically significantly lower in sera from chickens immunized with rOmpH or native OmpH purified using electroelution than in those of the three other treatment groups. The survival amongst chickens immunized with rOmpH or native OmpH purified using electroelution indicated high levels of protection. In contrast, survival probability was zero or low in the groups immunized with rOmpH purified using affinity chromatography and in the nonimmunized group. These findings show that the rOmpH purified using electroelution retains its immunogenicity and stimulates high levels of protection in chickens against P. multocida infection

An Intranasal Vaccination with a Recombinant Outer Membrane Protein H against Haemorrhagic Septicemia in Swamp Buffaloes

Hemorrhagic septicemia (HS) is an important infectious disease in cattle and buffaloes, caused by Pasteurella multocida B:2 and E:2. The intranasal recombinant OmpH-based vaccine was successfully used to protect dairy cattle from HS in a previous study. Thus, this study aimed to examine the protective ability of that vaccine among buffaloes. Four groups of Thai swamp buffaloes received different vaccines and were labeled as 100 or 200 μg of the rOmpH with CpG-ODN2007, commercial HS bacterin vaccine, and nonvaccinated control groups. Sera and whole blood were collected to examine the antibody levels and cellular immune response using indirect ELISA and MTT assay, respectively. Challenge exposure was performed with virulent P. multocida strain M-1404 serotype B:2 on day 72 of the experiment. The antibody titers to P. multocida among immunized buffaloes were significantly higher than in the control group (p<0.01), especially the 200 μg of the rOmpH group. The stimulation index (SI) of the intranasally vaccinated groups revealed significantly higher levels than the nonvaccinated group (p<0.01), but not different from the intramuscularly commercial HS vaccine. The clinical signs and high fever were observed after challenge exposure in the nonvaccinated group, while it was not observed among the 200 μg of rOmpH immunized buffaloes. The other immunized groups showed partial protection with transient fever. In conclusion, the rOmpH-based intranasal vaccine could elicit protective ability and induce antibody- and cell-mediated immune response against virulent P. multocida strain among swamp buffaloes