Submitted to: American Association of Veterinary Laboratory Diagnosticians
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/2006
Publication Date: 10/12/2006
Citation: O'Toole, D., Gailbreath, K.L., Oaks, J.L., Taus, N.S., Davis, W.C., Ghoddusi, M., Li, H. 2006. Pre-clinical and early clinical lesions of malignant catarrhal fever in bison following experimental inoculation with ovine nasal mucus containing ovine herpesvirus-2 (OvHV-2). American Association of Veterinary Laboratory Diagnosticians. 49th Annual Meeting of American Association of Veterinary Laboratory Diagnosticians, Minneapolis, Minn. 98. Interpretive Summary:
Technical Abstract: Malignant catarrhal fever is a common and fatal disease of American bison. Recently our group demonstrated that MCF can be induced experimentally in American bison by aerosol exposure to nasal secretions derived from sheep experiencing intensive shedding events. In the current study, we defined preclinical and early clinical morphological changes associated with MCF following experimental challenge. Sixteen bison were challenged with OvHV-2 by nebulizing 2 ml of nasal inoculum containing 10 million OvHV-2 DNA copies; the remaining two bison served as uninoculated controls. All 16 inoculated bison, and neither of the two controls, were positive for OvHV-2 by 22 days post nebulization (DPA). Pairs of bison were selected for post-mortem examination beginning at 23 DPA. Gross lesions were detected two asymptomatic bison at 26 DPN. Clinical signs were first evident at 28 DPN. The study showed that aerosol exposure of bison using 10 million OvHV-2 DNA copies reliably induces MCF, with onset of clinical signs of 28 DPN and detectable gross lesions at 26 DPN. Gross lesions of MCF in the pre-clinical/early clinical stages of the disease are found in bladder (hemorrhagic cystitis), cecum and colon (ulcerative typhlocolitis), and larynx-pharynx (laryngitis-pharyngitis). A consistent feature in inoculated bison is the presence of multifocal consolidation throughout all lobe of the lung, involving <1 - 5% of pulmonary parenchyma. This is the first report of pre-clinical lesions of MCF in any species.