AUTHOR=Tewari Deepanker , Fasnacht Melinda , Ritzman Margaret , Livengood Julia , Bower Jessica , Lehmkuhl Aaron , Nichols Tracy , Hamberg Alex , Brightbill Kevin , Henderson Davin 

TITLE=Detection of chronic wasting disease in feces and recto-anal mucosal associated lymphoid tissues with RT-QuIC in a naturally infected farmed white-tailed deer herd

JOURNAL=Frontiers in Veterinary Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.959555

DOI=10.3389/fvets.2022.959555

ISSN=2297-1769

ABSTRACT=<p>Chronic wasting disease (CWD) is an infectious prion disease affecting the cervids, including white-tailed deer (WTD) (<italic>Odocoileus virginianus</italic>). CWD is typically diagnosed <italic>postmortem</italic> in farmed cervids by immunohistochemistry (IHC). Amplification-based detection methods are newer generation tests currently being evaluated to improve the detection of prion disease. In addition to improving sensitivity, <italic>antemortem</italic> detection by amplification assays is a focus for improving disease control and management. In this study, we evaluate the use of real-time quaking-induced conversion (RT-QuIC) to detect CWD in fecal and recto-anal mucosal-associated lymphoid tissue (RAMALT) samples from naturally infected farmed WTD herds at <italic>postmortem</italic>. We successfully detected the presence of CWD prions in WTD RAMALT with a specificity of 100% and a sensitivity of 85.7% (<italic>n</italic> = 71) and in feces with a specificity of 100% and a sensitivity of 60% (<italic>n</italic> = 69), utilizing RT-QuIC on samples collected <italic>postmortem</italic>. Seeding activity detected in RAMALT (15.3 ± 4.2%, <italic>n</italic> = 18) was much stronger than in feces (44.4 ± 4.2%, <italic>n</italic> = 15), as measured by cycle threshold (Ct) and rise in relative fluorescence in samples collected from the same WTD. Prion detection in the RAMALT (94.7%) and feces (70.5%) was highest when both obex and retropharyngeal lymph nodes (RPLNs) were positive for CWD <italic>via</italic> IHC. In the study group, we were also able to test prion protein gene variants and associated disease susceptibility. A majority of tested WTD were the CWD genotype (96 GG) and also harbored the highest percentage of positive animals (43.7%). The second highest population of WTD was the genotype 96 GS and had a CWD positivity rate of 37.5%. Each of these groups showed no difference in RAMALT or fecal detection of CWD.</p>