Assessment of CWD prion shedding in deer saliva with occupancy modeling.

4 years ago

Assessment of CWD prion shedding in deer saliva with occupancy modeling.

Erin McNulty, Amy V Nalls, Edward A Hoover, Brittany A Mosher, Kristen A Davenport, Davin M Henderson, Nathaniel D Denkers, Brian M Brost, Candace K Mathiason

Detection of prions is difficult due to the peculiarity of the pathogen, which is a misfolded form of a normal protein. The specificity and sensitivity of detection methods are imperfect in complex samples, including excreta. Here, we combined optimized prion amplification procedures with a statistical method that accounts for false positive and false negative errors to test deer saliva for chronic wasting disease (CWD) prions. This approach enabled us to discriminate shedding of prions in saliva and detection of prions in saliva -- a distinction crucial to understanding the role of prion shedding in disease transmission and for diagnosis. We found that assay sensitivity and specificity were indeed imperfect, and we were able to draw several conclusions pertinent to CWD biology from our analyses: (1) shedding of prions in saliva increases with time post-inoculation, but is common throughout the pre-clinical phase of disease; (2) shedding propensity is influenced neither by sex nor by prion protein genotype at codon 96; and (3) the source of prion-containing inoculum used to infect deer affects the likelihood of prion shedding in saliva -- oral inoculation of deer with CWD(+) saliva resulted in 2.77 times the likelihood of prion shedding in saliva compared to inoculation with CWD(+) brain. These results are pertinent to horizontal CWD transmission in wild cervids. Moreover, the approach described is applicable to other diagnostic assays with imperfect detection.

Publisher URL: http://doi.org/10.1128/JCM.01243-17

DOI: 10.1128/JCM.01243-17