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Research Project: Non-Antibiotic Strategies to Control Priority Bacterial Infections in Swine

Location: Virus and Prion Research

Title: Potential use of outer membrane proteins as subunit vaccines against Haemophilus parasuis

item Brockmeier, Susan
item EBERLE, KIRSTEN - Orise Fellow
item MOU, KATHY - Orise Fellow
item HAU, SAMANTHA - Iowa State University
item Nicholson, Tracy
item Register, Karen

Submitted to: American Society for Microbiology General Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/27/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Haemophilus parasuis is a Gram-negative bacterium belonging to the Pasteurellaceae family that causes Glässer's disease in pigs, a disease characterized by polyserositis, meningitis and arthritis. There are at least 15 serotypes of H. parasuis and vaccines are largely limited to bacterins that provide homologous but limited heterologous protection. Outer membrane proteins (OMP) are potential targets for subunit vaccine development. Two prominent OMPs, P2 and P5, that were present in an outer membrane vesicle vaccine that was protective for pigs, were evaluated as potential subunit vaccine candidates. Five pigs each were vaccinated with either recombinant P2, P5, or both proteins in EmulsigenD adjuvant. Pigs were primed and boosted 3 weeks later intramuscularly with the respective vaccines. Three weeks after the boost vaccination, pigs were challenged with a virulent serotype 5 isolate, 29755, the same isolate from which the proteins were cloned. Vaccinated pigs developed high IgG antibody titers to the proteins they were vaccinated with; however, pigs vaccinated with P5 had higher IgG antibody responses when lysates of whole bacteria were used as antigen in the assay. Protein P5 appeared to be the better protective immunogen as only one out of the five pigs vaccinated with P5 alone, and two out of the five pigs vaccinated with both proteins developed disease, while four out of the five pigs vaccinated with P2 alone developed disease and had to be euthanized. Current experiments are examining additional proteins that may be conserved across serotypes to improve the protective response and increase the possibility of a more broadly cross protective H. parasuis vaccine.