Protection of Cattle against Epizootic Bovine Abortion (EBA) Using a Live <i>Pajaroellobacter abortibovis</i> Vaccine
Myra T. Blanchard,
Mike B. Teglas,
Mark L. Anderson,
Peter F. Moore,
Bret R. McNabb,
Kassidy M. Collins,
Bret V. Yeargan,
Jeffrey L. Stott
Affiliations
Myra T. Blanchard
Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California—Davis, 1 Shields Ave, Davis, CA 95616, USA
Mike B. Teglas
Department of Agriculture, Veterinary and Rangeland Sciences, University of Nevada, 1664 N. Virginia St., Reno, NV 89557, USA
Mark L. Anderson
Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California—Davis, 1 Shields Ave, Davis, CA 95616, USA
Peter F. Moore
Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California—Davis, 1 Shields Ave, Davis, CA 95616, USA
Bret R. McNabb
Department of Population Health and Reproduction, School of Veterinary Medicine, University of CA—Davis, 1 Shields Ave, Davis, CA 95616, USA
Kassidy M. Collins
Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California—Davis, 1 Shields Ave, Davis, CA 95616, USA
Bret V. Yeargan
Department of Pathology and Laboratory Medicine, University of California-Davis Health, 2315 Stockton Blvd., Davis, CA 95817, USA
Jeffrey L. Stott
Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California—Davis, 1 Shields Ave, Davis, CA 95616, USA
Epizootic bovine abortion (EBA) is an arthropod-borne bacterial disease that causes significant economic loss for cattle producers in the western United States. The etiologic agent, Pajaroellobacter abortibovis, is an intracellular pathogen that has yet to be cultivated in vitro, thereby requiring novel methodologies for vaccine development. A vaccine candidate, using live P. abortibovis-infected cells (P.a-LIC) harvested from mouse spleens, was tested in beef cattle. Over the course of two safety studies and four efficacy trials, safety risks were evaluated, and dosage and potencies refined. No incidence of anaphylaxis, recognized health issues or significant impact upon conception rates were noted. Vaccination did result in subclinical skin reactions. Early fetal losses were noted in two trials and were significant when the vaccine was administered within 21 days prior to conception. Administration of the EBA agent (EBAA) vaccine as a single dose, at a potency of 500 P.a–LIC, 56 days prior to breeding, provided 100% protection with no early fetal losses. Seroconversion occurred in all animals following EBAA vaccination and corresponded well with protection of the fetus from epizootic bovine abortion.