An injectable subunit vaccine containing Elongation Factor Tu and Heat Shock Protein 70 protects North American bison from Mycoplasma bovis infection

Authors: Kaplan, Bryan; Dassanayake, Rohana; Briggs, Robert; Kanipe, Carly; Boggiatto, Paola; CRAWFORD, LAUREN - Oak Ridge Institute For Science And Education (ORISE); Olsen, Steven; MENGHWAR, HARISH - Oak Ridge Institute For Science And Education (ORISE); Casas, Eduardo; Tatum, Fred

Submitted to: Frontiers in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2024
Publication Date: 6/26/2024
Citation: Kaplan, B.S., Dassanayake, R.P., Briggs, R.E., Kanipe, C.R., Boggiatto, P.M., Crawford, L., Olsen, S.C., Menghwar, H., Casas, E., Tatum, F.M. 2024. An injectable subunit vaccine containing Elongation Factor Tu and Heat Shock Protein 70 protects North American bison from Mycoplasma bovis infection. Frontiers in Veterinary Science. 11. Article 1408861. https://doi.org/10.3389/fvets.2024.1408861.
DOI: https://doi.org/10.3389/fvets.2024.1408861

Interpretive Summary: Mycoplasma bovis (M. bovis) is a bacteria that causes severe respiratory disease in North American bison. Despite causing many high mortality outbreaks for over 20 years, there is no commercially available vaccine licensed for use in bison. In this study, we evaluated an experimental vaccine comprised of two M. bovis proteins, EFTu and Hsp70, in bison. Vaccinated bison produced antibody and had measurable cellular responses specific for both M. bovis proteins in the vaccine that were not observed in unvaccinated bison. Both vaccinated and unvaccinated bison were then intranasally infected with M. bovis. Vaccinated bison had lower lung bacterial loads, lung pathology, and spread of M. bovis outside of the lungs compared to unvaccinated bison. These results show that this subunit vaccine can reduce disease, bacterial load, and bacterial spread in experimentally infected bison.

Technical Abstract: Mycoplasma bovis (M. bovis) is the etiologic agent of high mortality epizootics of chronic respiratory disease in North American bison (Bison bison). Despite the severity of the disease, no efficacious commercial vaccines have been licensed for the prevention of M. bovis infection in bison. Elongation Factor Thermal unstable (EFTu) and Heat shock protein 70 (Hsp70, DnaK) are highly conserved, constitutively expressed proteins. These moonlighting proteins can be simultaneously located in the cytoplasm and associated with the plasma membrane of bacterial cells and have previously been shown to provide protection against M. bovis infection in cattle. Herein, we evaluated an injectable, adjuvanted subunit vaccine comprised of recombinantly expressed EFTu and Hsp70 for efficacy in bison. Bison that received two doses of vaccine developed robust antibody and cellular immune responses against both EFTu and Hsp70 antigens. Unvaccinated control and vaccinated bison were experimentally challenged with Bovine Herpes Virus-1 (BHV-1) four days prior to intranasal infection with M. bovis. Bison were euthanized at 26-28 days post-infection. BHV-1 and M. bovis were detected in nasal swab samples collected from all animals throughout the study. Reductions in joint infection, lung bacterial loads, and lung lesions were observed in vaccinated bison compared to unvaccinated controls. Two unvaccinated bison were euthanized prior to the study endpoint as they exhibit severe clinical signs including lameness, lethargy, tachypnea, and labored breathing. Together, these results showed that this subunit vaccine reduced disease and in M. bovis challenged bison.