title: Molecular identification of a novel deltaproteobacterium as the etiologic agent of epizootic bovine abortion (foothill abortion).
abstract: Epizootic bovine abortion (EBA) is endemic in California's coastal range and the foothill regions of the Sierra Nevada, where it has been the primary diagnosed cause of abortion in beef cattle for >50 years. Investigation of these losses has defined a specific fetal syndrome characterized by late-term abortion or birth of weak or dead calves. Although the unusual clinical presentation and unique fetal pathology associated with EBA have been recognized since the 1950s, the identity of the etiologic agent is unknown. In this study, suppression-hybridization PCR was used to identify a fragment of the 16S rRNA gene of a previously undescribed bacterium in thymus tissue derived from affected fetuses. Phylogenetic analysis revealed that this pathogen was a deltaproteobacterium closely related to members of the order Myxococcales. A specific PCR was subsequently developed to detect the presence of this bacterium in DNA extracted from fetal thymuses. Using histopathology as the definitive diagnosis for EBA, this PCR demonstrated 100% specificity and 88% sensitivity. The bacterium was also detected in the argasid tick Ornithodoros coriaceus, which is the recognized vector of EBA. These data imply a close association between this novel agent and the etiology of EBA.
authors.affiliation: Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA, USA.
authors.forename: Donald P
authors.initials: DP
authors.lastname: King
authors.forename: Ching-I
authors.initials: CI
authors.lastname: Chen
authors.forename: Myra T
authors.initials: MT
authors.lastname: Blanchard
authors.forename: Brian M
authors.initials: BM
authors.lastname: Aldridge
authors.forename: Mark
authors.initials: M
authors.lastname: Anderson
authors.forename: Richard
authors.initials: R
authors.lastname: Walker
authors.forename: John
authors.initials: J
authors.lastname: Maas
authors.forename: Don
authors.initials: D
authors.lastname: Hanks
authors.forename: Mark
authors.initials: M
authors.lastname: Hall
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Stott
mesh_terms: D000034:Abortion, Veterinary / Q000382:microbiology*; D000818:Animals; D001096:Arachnid Vectors / Q000382:microbiology; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D020564:Deltaproteobacteria / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D005260:Female; D005315:Fetal Diseases / Q000382:microbiology / Q000662:veterinary; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000662:veterinary*; D008969:Molecular Sequence Data; D026861:Ornithodoros / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000382:microbiology / Q000662:veterinary; D012680:Sensitivity and Specificity; D013577:Syndrome; D013950:Thymus Gland / Q000382:microbiology