EPIZOOTIC BOVINE ABORTION PDF
Characterization of Pajaroellobacter abortibovis, the etiologic agent of epizootic bovine abortion. Brooks RS(1), Blanchard MT(1), Clothier. J Vet Diagn Invest. May;14(3) Diagnosis of epizootic bovine abortion in Nevada and identification of the vector. Hall MR(1), Hanks D, Kvasnicka W. Kennedy PC, Casaro AP, Kimsey PB, Bon Durant RH, Bushnell RB, Mitchell GM. The development of the fetal lesions of epizootic bovine abortion (EBA) was.
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The novel bacterium described in this paper represents only the second member of the delta subdivision of the class Proteobacteria to be a mammalian pathogen the first was Lawsonia intracellularis [ 413 ], the causative agent of porcine proliferative enteropathy.
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The microbe, which has yet to be successfully abortin in vitro, has proven difficult to purify from necropsy tissues. Two specific PCRs were subsequently developed to detect these agents separately in a panel of individual bovine thymus tissues derived from five EBA-positive and four EBA-negative animals. Experimental and epizootiologic evidence associating Ornithodoros coriaceus Koch Acari: In an additional experiment, six heifers were challenged with aliquots of a single thymus tissue pool previously demonstrated to be capable aborion transmitting EBA A combination of direct sequencing bp from 25 EBA-positive fetuses representing epizoottic field cases, four experimental tick transmissions, and five experimental tissue transmissions, the last using thymus homogenate derived from an EBA-positive fetus and Southern blotting of these amplicons was used to confirm PCR specificity.
Etiological studies on epizootic bovine abortion. Congenital spirochetosis in calves: Thymic lesions unique to EBA include a loss of cortical thymocytes and extensive infiltration of macrophages into the medulla.
These three heifers gave birth to healthy calves; two were euthanized immediately prior to consumption of colostrum for PCR analysis; all tissues were PCR negative. Preliminary data demonstrated the EBA agent to be present in 4 of 11 nymphs tested and 2 of 8 female ticks tested; The nucleic acid sequences were the same five were directly sequenced to confirm the identity of the PCR product epiaootic that identified in EBA fetal bovine tissues.
Preliminary characterization and pathogenicity studies of a virus isolated from ticks Ornithodoros coriaceus and from tick-exposed cattle. This study establishes the presence of EBA as a cause of late-term abortion in Nevada.
Characterization of Pajaroellobacter abortibovis, the etiologic agent of epizootic bovine abortion.
Published by Elsevier B. Widespread inflammatory lesions with a vascular orientation are evident in most tissues. The agent was detected in thymic tissues from affected fetuses and in the argasid tick vector of EBA.
In the 43 years since the first description in California, epizootic bovine abortion EBA has been considered but not definitively diagnosed as a cause of late-term abortions on Nevada ranches. The scale represents percent nucleotide substitutions per site. Since nucleic acid samples extracted from ticks can often exhibit activity inhibitory to PCR, it was vital to establish an internal amplification control to discriminate true- and false-negative PCR results.
The focus of the current study was to further expand the morphologic characterization and taxonomic placement of this bacteria, named here as Pajaroellobacter abortibovis. While attempts to sequence ten universally conserved protein-coding genes using previously published degenerative primers failed, redesigned primers based solely upon Deltaproteobacteria facilitated the partial sequencing of two genes; fusA JQ and pyrG JQ Concurrent treatment with antibiotics at the time of EBA challenge abolished infection of the fetus and therefore implicated a prokaryotic organism as the likely causative agent Thus, phylogenetic characterization has been limited to analysis of the 16S ribosomal RNA rRNA gene AFwhich placed this bacterium in the order Myxococcales, suborder Sorangiineae, family Polyangiaceae and most closely related to Sorangium cellulosum.
Examination of aborted full-term bovine fetuses obtained from Nevada ranches revealed gross abnormalities consistent with EBA enlarged lymph nodes, petechial hemorrhages of the oral mucosa and conjunctiva, ascites, and splenohepatomegalyand EBA was confirmed by histologic examination of fetal tissues. In addition to identifying this novel agent in diseased fetal bovine tissues, PCR has also demonstrated the presence of the deltaproteobacterium in the tick vector, O.
Primers designed in a similar fashion generated a partial sequence of the 23S rRNA gene JQ These sequences, combined with a revised 16S rRNA phylogenic analysis, support the placement of this bacteria as a unique genus separate from Sorangium.
Although the unusual clinical presentation and unique fetal pathology associated with EBA have been recognized since the s, the identity of the etiologic agent is unknown.
The use of shPCR allowed prokaryotic sequences derived from bovine tissues to be amplified in preference to contaminating bacteria. Carbon dioxide as an attractant for certain ticks Acarina: The bacterium was also detected in the argasid tick Ornithodoros coriaceuswhich is the recognized vector of EBA.
It has been hypothesized that driver-tester hybridization suppresses the amplification of ubiquitous bacterial 16S rRNA sequences, allowing unique bacterial sequences present only in the EBA-positive tissue samples to be amplified.
Efforts are under way to define additional gene sequences of this unique pathogen, to visualize the agent in affected tissues, and to visually link the rRNA sequence to the bacterium using in situ hybridization techniques on diseased fetal necropsy tissue.
A quantitative serologic assay for diagnosing congenital infections of cattle. The nucleotide sequence data reported in this paper have been submitted to GenBank and have been assigned the following accession numbers: Heifer exposure n Diagnosis a No.
Diagnosis of epizootic bovine abortion in Nevada and identification of the vector.
In contrast, the three challenge control fetuses whose dams did not receive antibiotics all presented with classic EBA-associated lesions, and their tissues were PCR positive. Acute vasculitis developed epizooic the same time as the epizoootic focal-necrotizing lesions.
Hovine, the PCR failed to amplify DNA extracted from pure cultures of a selection of bacterial pathogens typically encountered in veterinary medicine or even P. Epizootiologic and immunologic studies of epizootic bovine abortion. A diagnosis of EBA was established on the basis of histopathology and elevated serum immunoglobulin G, as previously defined 910 National Center for Biotechnology InformationU.
The majority of guidelines that have been suggested for sequence-based determination and incriminating of a presumptive microorganism in disease 5 have been satisfied. The present study employed an shPCR technique in an attempt to identify a bacterial agent present in fetal thymic tissues collected from EBA cases.