Identification of candidate vaccine antigens using 2-D gel electrophoresis and immunoproteomics for cross protection against Glaesserella parasuis

Authors: Hau, Samantha; EBERLE, KIRSTEN - Oak Ridge Institute For Science And Education (ORISE); Nally, Jarlath; Nielsen, Daniel; Lippolis, John; Brockmeier, Susan

Submitted to: Veterinary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/7/2025
Publication Date: 6/9/2025
Citation: Hau, S.J., Eberle, K.C., Nally, J.E., Nielsen, D.W., Lippolis, J.D., Brockmeier, S. 2025. Identification of candidate vaccine antigens using 2-D gel electrophoresis and immunoproteomics for cross protection against Glaesserella parasuis. Veterinary Microbiology. 307. Article 110594. https://doi.org/10.1016/j.vetmic.2025.110594.
DOI: https://doi.org/10.1016/j.vetmic.2025.110594

Interpretive Summary: Glaesserella parasuis is a bacteria that causes severe disease in pigs and can lead to death. G. parasuis strains are identified by the capsule they produce. Capsule is a sugar matrix that surrounds the cell. This matrix protects the cell from the host immune system and the environment. Because of the capsule, using vaccines made from killed bacteria tends to produce immunity specific to the strain used in the vaccine or the capsule type (serotype) of that strain. G. parasuis is difficult to control because farms can have multiple isolates with different capsule types. This requires immunity that is protective against many strains and serotypes. Alternative vaccine platforms, including subunit vaccines, are a new solution that could provide broad protection. Subunit vaccines are made from one or multiple proteins produced by the bacteria. Subunit vaccines can provide protection against many serotypes and strains because they use proteins that are very similar between all strains. This study identified G. parasuis proteins using serum from animals protected against G. parasuis disease. Thirteen proteins were associated with the protective immune response. Two groups of proteins were tested for their ability to protect pigs against G. parasuis infection: LpoA/YaeT/AbpE and LppA/LpoA/YaeT. The vaccine containing LppA/LpoA/YaeT protected pigs against disease with two G. parasuis strains. This work identified a new vaccine candidate for G. parasuis. It also describes a new method to identify subunit vaccine candidates.

Technical Abstract: Glaesserella parasuis infection in swine causes polyserositis, arthritis, and meningitis. A range of virulent to nonvirulent strains exists between and within the 15 serovars. This has created difficulty in generating broadly protective vaccines against G. parasuis. Subunit vaccines are of interest in protection against bacterial pathogens, where the individual proteins within the vaccine are highly conserved and widely present. To identify novel subunit vaccine candidates for heterologous protection against G. parasuis, previously generated serum from bacterin vaccinated pigs that were protected (HS069 bacterin) or non-protected (Nagasaki bacterin) against heterologous challenge with 12939 was used to differentiate the antibody response using 2-D gel electrophoresis and immunoblotting. Proteins with differential representation between blots probed with serum from HS069 or Nagasaki bacterin vaccinated animals were identified by mass spectrometry. Thirteen unique proteins were associated with the protective immune response and four of these proteins were tested in two combinations against G. parasuis in a swine challenge model (ApbE, LpoA, YaeT, and LppA). All four proteins were immunogenic and stimulated high antibody titers in pigs. While the protein combination of ApbE, LpoA, and YaeT did not provide improved survival, the combination of LpoA, YaeT, and LppA did, suggesting LppA is important for protection. This work identified a group of proteins capable of improving survival in pigs challenged with G. parasuis. Additionally, this work highlights a novel and effective method to identify candidate vaccine antigens utilizing the protective immune response.