Submitted to: Journal of General Virology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/3/2002
Publication Date: 10/20/2002
Citation: Wild, M.A., Spraker, T.R., Sigurdson, C.J., Orourke, K.I., Miller, M.A. 2002. Preclinical diagnosis of chronic wasting disease in captive mule deer (odocoileus heminonus) and white tailed deer (odocoileus virginianus) using tonsillar biopsy. Journal of General Virology. 83: 2629-2634. Interpretive Summary: Chronic wasting disease is a fatal neurologic disease of deer, with some similarities to scrapie of sheep and goats. The disease has a long preclinical period, in which infected deer appear normal but may be transmitting the disease through yet unknown transmission routes. Identification of infected deer, particularly in research and captive breeding settings, is important for pathogenesis studies and management practices. The marker protein for the disease appears in the tonsil well before clinical signs begin. In this paper, a technique for sampling the tonsil in live deer under general anesthesia is described and evaluated. The technique was shown to be useful for identifying infected animals and will be an important research tool.
Technical Abstract: The usefulness of tonsillar biopsy on live deer for preclinical diagnosis of the transmissible spongiform encephalopathy chronic wasting disease (CWD) was evaluated. Disease was tracked in a CWD-endemic herd using serial tonsillar biopsies collected at 6-9 month intervals from 34 captive mule deer (Odocoileus hemionus) and five white-tailed deer (O. virginianus). Tonsillar biopsies were examined for accumulation of PrPCWD, the protein marker for infection, using immunohistochemical (IHC) staining. 26/34 (76%) mule deer and 4/5 (80%) white-tailed deer had PrPCWD accumulation in tonsillar biopsies; CWD was subsequently confirmed by postmortem examination in all 30 of these tonsillar positive deer. Six mule deer with IHC negative tonsillar biopsies had positive brain and tonsillar IHC staining upon death 12 to 40 months following the last biopsy. PrPCWD accumulation in tonsillar biopsy was observed 2 to 20 months before CWD-related death and up to 14 months before onset of clinical signs of CWD. Tonsillar biopsies from 3-month-old mule deer (n = 6) were IHC negative, but PrPCWD accumulation was detected in tonsillar biopsies from seven of ten mule deer by 19 months of age. Tonsillar biopsy evaluated with IHC staining is a useful technique for the preclinical diagnosis of CWD in live mule deer and white-tailed deer when intensive management approaches are possible.