Real-Time Quaking-Induced Conversion Detection of PrPSc in Fecal Samples From Chronic Wasting Disease Infected White-Tailed Deer Using Bank Vole Substrate.

Soyoun Hwang,Justin J. Greenlee,Eric M. Nicholson

doi:10.3389/fvets.2021.643754

Abstract

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) that is fatal to free-range and captive cervids. CWD has been reported in the United States, Canada, South Korea, Norway, Finland, and Sweden, and the case numbers in both wild and farmed cervids are increasing rapidly. Studies indicate that lateral transmission of cervids likely occurs through the shedding of infectious prions in saliva, feces, urine, and blood into the environment. Therefore, the detection of CWD early in the incubation time is advantageous for disease management. In this study, we adapt real-time quacking-induced conversion (RT-QuIC) assays to detect the seeding activity of CWD prions in feces samples from clinical and preclinical white-tailed deer. By optimizing reaction conditions for temperature as well as the salt and salt concentration, prion seeding activity from both clinical and preclinical animals were detected by RT-QuIC. More specifically, all fecal samples collected from 6 to 30 months post inoculation showed seeding activity under the conditions of study. The combination of a highly sensitive detection tool paired with a sample type that may be collected non-invasively allows a useful tool to support CWD surveillance in wild and captive cervids.

Highlights

Chronic wasting disease (CWD) is a form of transmissible spongiform encephalopathy (TSE) or prion disease affecting cervids including deer, elk, reindeer, and moose
Using higher salt concentrations (400 and 500 mM NaCl) improved the seeding activity with shorter lag time for assays seeded with feces from positive animal samples while assays seeded with feces from negative control samples remain below the threshold to be considered positive (Figures 1D,E)
Similar to the results observed for non-enriched samples, all tested NaCl concentrations, except 300 mM NaCl, result in fibril seeding based on an observed increase in thioflavin T (ThT) fluorescence (Figure 2)

Summary

Introduction

Chronic wasting disease (CWD) is a form of transmissible spongiform encephalopathy (TSE) or prion disease affecting cervids including deer, elk, reindeer, and moose. Chronic wasting disease infected cervids have misfolded prion proteins distributed widely, in the nervous system and in lymphoid tissues, muscle, and blood [5,6,7]. These animals are known to shed prions into the environment via saliva, urine, blood, and feces. This environmental contamination is often suggested to be the cause for horizontal CWD transmission among captive

Methods

Results

Conclusion