Quantitative duplex TaqMan real-time polymerase chain reaction for the assessment of the etiologic agent of epizootic bovine abortion

J Vet Diagn Invest. 2011 Nov;23(6):1153-9. doi: 10.1177/1040638711425573. Epub 2011 Oct 20.

Abstract

Epizootic bovine abortion (EBA), also commonly known as "foothill abortion," is a late-term abortion primarily in beef cattle with significant economic impacts in California, Nevada, and Oregon. The causative agent is a novel deltaproteobacterium (aoEBA) closely related to the order Myxococcales and vectored by the soft-shelled tick Ornithodoros coriaceus. Historically, diagnosis has relied upon the pathologic examination of the fetus and the presence of elevated fetal serum immunoglobulins. Identification of the etiologic agent, a unique deltaproteobacterium, permitted the development of a quantitative duplex real-time polymerase chain reaction (qPCR) using a unique 90-bp sequence of aoEBA 16S ribosomal RNA gene in conjunction with an 88-bp sequence of the bovine β-actin gene. Reaction efficiencies were 100.9% for the 16S aoEBA gene and 93.1% for the bovine β-actin gene. Application of the duplex TaqMan to a set of aoEBA-infected fetal bovine necropsy tissues demonstrated the assay to be robust in quantitatively identifying the aoEBA bacteria and establishing host-tissue pathogen load. Consistent with previously reported immunohistochemical data, organized lymphoid tissue generally carried the heaviest bacterial load as compared to non-lymphoid tissue. The newly developed duplex TaqMan assay will facilitate diagnosis in difficult cases and provide an invaluable tool for delineating the pathogenesis of EBA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aborted Fetus / microbiology
  • Abortion, Veterinary / microbiology*
  • Animals
  • Antibodies, Bacterial
  • Cattle
  • Deltaproteobacteria / genetics
  • Deltaproteobacteria / isolation & purification*
  • Female
  • Gene Expression Regulation, Bacterial / physiology
  • Immunoglobulin G
  • Immunoglobulin M
  • RNA, Ribosomal, 16S / genetics
  • Real-Time Polymerase Chain Reaction / methods
  • Real-Time Polymerase Chain Reaction / veterinary*

Substances

  • Antibodies, Bacterial
  • Immunoglobulin G
  • Immunoglobulin M
  • RNA, Ribosomal, 16S