Detection of chronic wasting disease in mule and white-tailed deer by RT-QuIC analysis of outer ear
Natalia Ferreira, Jorge M. Charco, Jakob Plagenz, Christina D. Orrú, Nathanial D. Denkers, Michael A. Metrick, Andrew G. Hughson, Karen A. Griffin, Brent Race, Edward A. Hoover, Joaquı́n Castilla, Tracy A. Nichols, Michael W. Miller, Byron Caughey
Abstract
Efforts to contain the spread of chronic wasting disease (CWD), a fatal, contagious prion disease of cervids, would be aided by the availability of additional diagnostic tools. RT-QuIC assays allow ultrasensitive detection of prion seeds in a wide variety of cervid tissues, fluids and excreta. The best documented antemortem diagnostic test involving RT-QuIC analysis targets lymphoid tissue in rectal biopsies. Here we have tested a more easily accessed specimen, ear pinna punches, using an improved RT-QuIC assay involving iron oxide magnetic extraction to detect CWD infections in asymptomatic mule and white-tailed deer. Comparison of multiple parts of the ear pinna indicated that a central punch spanning the auricular nerve provided the most consistent detection of CWD infection. When compared to results obtained from gold-standard retropharyngeal lymph node specimens, our RT-QuIC analyses of ear samples provided apparent diagnostic sensitivity (81%) and specificity (91%) that rivaled, or improved upon, those observed in previous analyses of rectal biopsies using RT-QuIC. These results provide evidence that RT-QuIC analysis of ear pinna punches may be a useful approach to detecting CWD infections in cervids.