Abstract
The diagnosis of chronic wasting disease (CWD) relies on demonstration of the disease-associated misfolded CWD prion protein (PrPCWD) in brain or retropharyngeal lymph node tissue by immunodetection methods, e.g. ELISA and immunohistochemistry (IHC). The success of these methods relies on a quality sample of tissues, which requires both anatomical knowledge and considerable dissection to collect. As the prevalence of CWD continues to increase globally, the development of fast and cost-effective methods to detect the disease is vital to facilitate CWD detection and surveillance. To address these issues, we have evaluated third eyelids from CWD-infected deer and elk using real-time quaking induced conversion (RT-QuIC). We identified prion seeding activity in third eyelids in 24 of 25 (96%) CWD-infected white-tailed deer (Odocoileus virginianus). We detected RT-QuIC positivity in the third eyelid as early as 1 month after experimental CWD exposure. In addition, we identified prion seeding activity in third eyelids of 18 of 25 (72%) naturally exposed asymptomatic CWD-positive rocky mountain elk (Cervus canadensis nelson). We compared CWD detection by RT-QuIC and IHC in third eyelid, retropharyngeal lymph node, and brain in 10 deer in early symptomatic stage of disease. IHC detected PrPCWD deposition in third eyelid lymphoid follicles in 5 of 10 deer (50%) whereas third eyelids of all 10 animals were positive by RT-QuIC. This difference reflected in part a lower requirement for lymphoid follicle presence for seeding activity detection by RT-QuIC. In conclusion, RT-QuIC analysis of the third eyelid, an easily accessed tissue, has potential to advance CWD detection and testing compliance.
Highlights
Chronic Wasting Disease (CWD) is a fatal contagious prion disease affecting cervid species that is characterized by neurodegeneration, emaciation, and abnormal behaviors [1,2,3,4,5]
To evaluate whether real-time quaking induced conversion (RT-QuIC) could detect CWD in third eyelid tissue, we examined third eyelids collected at necropsy from n = 25 white-tailed deer (WTD) experimentally exposed to CWD-positive saliva or brain homogenate, usually by the oral, or in one study, the aerosol route [27]
False positive wells in negative control third eyelids were well below a level of significance (2 false positive replicates of 44 total replicates (4.5%) (Fig 1E). These results demonstrated that the third eyelid can be used in RT-QuIC assay to consistently detect PrPCWD amyloid seeding activity from a variety of CWD-infected, symptomatic WTD with little false positivity
Summary
Chronic Wasting Disease (CWD) is a fatal contagious prion disease affecting cervid species (deer, elk, and moose) that is characterized by neurodegeneration, emaciation, and abnormal behaviors [1,2,3,4,5]. CWD, first identified in Colorado, now is found in North America, South. RT-QuIC detection of CWD in third eyelids. Foundation for the National Institutes of Health, P01-AI-077774, to Dr Edward A. Hoover; and the Foundation for the National Institutes of Health, R01-AI112956, to Dr Candace K. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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