Detection of prions from spiked and free-ranging carnivore feces

Abstract

Chronic wasting disease (CWD) is a highly contagious, fatal neurodegenerative disease caused by infectious prions (PrP ^CWD) affecting wild and captive cervids. Although experimental feeding studies have demonstrated prions in feces of crows ( Corvus brachyrhynchos), coyotes ( Canis latrans), and cougars ( Puma concolor), the role of scavengers and predators in CWD epidemiology remains poorly understood. Here we applied the real-time quaking-induced conversion (RT-QuIC) assay to detect PrP ^CWD in feces from cervid consumers, to advance surveillance approaches, which could be used to improve disease research and adaptive management of CWD. We assessed recovery and detection of PrP ^CWD by experimental spiking of PrP ^CWD into carnivore feces from 9 species sourced from CWD-free populations or captive facilities. We then applied this technique to detect PrP ^CWD from feces of predators and scavengers in free-ranging populations. Our results demonstrate that spiked PrP ^CWD is detectable from feces of free-ranging mammalian and avian carnivores using RT-QuIC. Results show that PrP ^CWD acquired in natural settings is detectable in feces from free-ranging carnivores, and that PrP ^CWD rates of detection in carnivore feces reflect relative prevalence estimates observed in the corresponding cervid populations. This study adapts an important diagnostic tool for CWD, allowing investigation of the epidemiology of CWD at the community-level.