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Updated: Mar 9, 2026
Immuno-fluorescence Assay of Leptospiral Surface-exposed Proteins
Published on: July 1, 2011
Identification of a surface epitope specific of virulent strains of Haemophilus parasuis
Florencia Correa-Fiz1, Nuria Galofre-Mila1, Mar Costa-Hurtado1
1IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain.
Abstract:
Haemophilus parasuis is a bacterium from the Pasteurellaceae family that comprises strains of different degree of virulence. Non-virulent strains are considered components of the upper respiratory tract microbiota, while virulent strains can invade systemic organs and cause fibrinous polyserositis (Glässer's disease). Genomic comparison of virulent and non-virulent strains led to the identification of a family of genes differentially associated to virulence, the virulence-associated trimeric autotransporters (vtaA). Monoclonal antibody 69C6 reacted with the surface of virulent strains and has allowed now the identification of an epitope in the C terminus of the passenger domain of the VtaAs from virulent strains. Protein modelling indicated that the epitope is probably exposed, although sera from pigs vaccinated with the passenger domain of VtaA9 and from convalescent animals did not react with the 69C6 epitope. Induction of antibodies against the 69C6 epitope by vaccination would allow a response targeting specifically virulent strains of H. parasuis.
Insights
Haemophilus parasuis virulence-associated trimeric autotransporters (vtaA) were studied. A specific epitope on virulent strains was identified, offering potential for targeted vaccines against Glässer
Area of Science:
- Veterinary Microbiology
- Bacterial Pathogenesis
- Immunology
Background:
- Haemophilus parasuis causes Glässer's disease in pigs.
- Virulent strains possess virulence-associated trimeric autotransporters (vtaA) not found in non-virulent strains.
- Understanding vtaA function is key to controlling H. parasuis infections.
Purpose of the Study:
- To identify and characterize a specific surface epitope on virulent H. parasuis strains.
- To evaluate the potential of this epitope for targeted vaccine development.
Main Methods:
- Genomic comparison of virulent and non-virulent H. parasuis strains.
- Monoclonal antibody (69C6) characterization and epitope mapping.
- Protein modeling to assess epitope accessibility.
- Serological assays using pig sera.
Main Results:
- A conserved epitope was identified in the C-terminus of the VtaA passenger domain of virulent H. parasuis strains.
- The epitope is likely surface-exposed based on protein modeling.
- Antibodies from pigs vaccinated with VtaA9 passenger domain or convalescent pigs did not recognize this specific 69C6 epitope.
Conclusions:
- The 69C6 epitope represents a potential target for strain-specific vaccines against virulent H. parasuis.
- Further research is needed to develop vaccination strategies that elicit antibodies against this epitope.
- Targeting virulent H. parasuis strains could reduce Glässer's disease incidence.
