PREVENTION AND CONTROL STRATEGIES FOR TUBERCULOSIS IN CATTLE AND WILDLIFE RESERVOIRS
Location: Infectious Bacterial Diseases Research Unit
Title: Active and latent ovine Herpesvirus-2 (OvHV-2) infection in a herd of captive white-tailed deer (Odocoileus virginianus)
Submitted to: Journal of Comparative Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 16, 2013
Publication Date: March 2, 2013
Citation: Palmer, M.V., Thacker, T.C., Madison, R.J., Koster, L., Swenson, S., Li, H. 2013. Active and latent ovine Herpesvirus-2 (OvHV-2) infection in a herd of captive white-tailed deer (Odocoileus virginianus). Journal of Comparative Pathology [e-pub ahead of print]. Available: http://dx.doi.org/10.1016/j.jcpa.2013.01/005.
Interpretive Summary: Malignant catarrhal fever (MCF) is a viral disease affecting cattle and numerous other ruminants. Not all infected species develop disease. Reservoir hosts, such as sheep, carry and shed virus but do not show clinical signs. Other species such as cattle, deer and bison can develop severe and often fatal disease. In deer it is believed that infection results in severe clinical signs and often death. It has been assumed that deer do not carry MCF virus and therefore are not contagious to other deer or any other susceptible species. It has also been assumed that deer do not become latently infected similar to sheep. In a captive white-tailed deer herd it was shown that some deer carry MCF virus without clinical signs, sometimes for years. These results suggest that latent infection and deer to deer transmission should be considered when managing MCF in deer herds.
Malignant catarrhal fever (MCF) is the clinical manifestation of infection of certain ruminant species with one of a group of pathogenic gammaherpesviruses known as MCF viruses. Cattle and numerous exotic ruminants are susceptible to clinical disease that may be sporadic or epidemic in nature. The most common MCF virus is ovine herpesvirus-2 (OvHV-2). Reservoir hosts, such as sheep, carry and excrete OvHV-2, absent clinical signs, while clinically susceptible species develop severe and often fatal disease. The existence of latent infection in clinically susceptible hosts is poorly understood. In a captive white-tailed deer herd 26 deer died between October 2006 and December 2010. Fifteen of twenty-six deer (58%) showed clinical signs, gross, and microscopic lesions consistent with MCF, while 11 (42%) did not. PCR amplification yielded product consistent with OvHV-2 DNA in spleen samples from all 26 deer. To examine the possibility of latent infection in this herd, peripheral blood mononuclear cells were examined by PCR for OvHV-2 DNA, which was positive in 23/32 (72%) clinically normal deer. Archived serum samples were used to examine the history of MCF exposure in this herd using a cELISA, which demonstrated that 10/40 (25%) deer had MCF viral antibodies, with 9 deer seropositive over multiple years. These results suggest the existence of latent infection of white-tailed deer with OvHV-2.