Detection of an immunological response in heifers experimentally infected with epizootic bovine abortion (foothill abortion)

Epizootic bovine abortion (EBA) is a tick transmitted abortive disease of beef cattle in the western United States. Infected cattle show no apparent clinical signs of disease until abortion occurs, usually within the last trimester of gestation. Recent research supports the role of a unique deltaproteobacteria in the etiology of EBA. To determine if a detectable immune response exists to the etiologic agent, hematologic data from eleven pregnant experimentally infected heifers and five control heifers was taken every seven days during the course of infection. Lymphopenia, monocytosis, and elevated IgG concentrations were evident over the course of infection in the EBA infected heifers, but not in the control heifers. Additionally, using primers specific to the agent of EBA, whole blood and buffy coat samples were subjected to PCR and southern blotting to determine if systemic infection by the etiologic agent during infection could be detected. The evidence of the pathogen could not be detected in the blood of infected heifers at any time during the experimental infection.