Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/15/2007
Publication Date: 9/26/2007
Citation: Spraker, T, Greenlee, J., Gidlewski T., O’Rourke, K. 2007. Abnormal Prion Protein in the Retina of Rocky Mountain Elk (Cervus Elaphus Nelsoni) [abstract]. Prion 2007. Paper No. P03.70. p. 64.
Technical Abstract: Background: Chronic wasting disease (CWD), a transmissible spongiform encephalopathy, has been reported in captive and free-ranging mule deer (Odocoileus hemionus hemionus), white-tailed deer (Odocoileus virginianus) and Rocky Mountain elk (Cervus elaphus nelsoni). An abnormal isoform of a prion protein (PrP**CWD) that has been associated with CWD has been reported in numerous internal organs other than the brain and lymphoid tissues including the retina of mule deer. Objective: Investigate the possibility of PrP**CWD in the retina of elk with CWD. Methods: Eyes from nine elk (genotype at codon 132: 6MM, 1ML and 2LL) were collected and fixed in Davidson's fixative, sectioned and immunostained stained with Anti-Prion 99 (Ventana Medical Systems, Inc. Tucson AZ) and P34. Slides were also stained with hematoxylin and eosin. Results: Prion was only found in the retina, all other regions of the eye were free of PrP**CWD. PrP**CWD was found in 8 of 10 layers of the retina and the optic nerve. Patterns of PrP**CWD observed in the MM and ML elk were different as compared to the LL elk. An occasional ganglion cell within the ganglion cell layer contained an intracytoplasmic vacuole. Conclusion: Elk in the later stages of CWD have an abundance of PrP**CWD in retinal tissues and optic nerve. This lesion may affect vision in these elk. Genotypes did result in different patterns within the retina. The LL genotype at codon 132, which has a prolonged incubation period, had much less PrP**CWD in the retina especially within the inner and outer plexiform layers. Also the LL elk seemed to have more intracytoplamsic staining within ganglia cells as compared to the MM and ML elk.