Study advances CWD prion testing in preserved lymph nodes

A new study in the Journal of Veterinary Diagnostic Investigation reports that researchers optimized a real-time quaking-induced conversion, or RT-QuIC, method to detect chronic wasting disease prions in preserved retropharyngeal lymph nodes from white-tailed deer, including both formalin-fixed and formalin-fixed paraffin-embedded samples. The work, led by investigators at the University of Pennsylvania, found that formalin-fixed samples reached up to 96% sensitivity and 100% specificity, while paraffin-embedded samples reached up to 98% sensitivity and 99% specificity. That’s notable because standard CWD workflows typically split samples between fresh or frozen tissue for ELISA and fixed tissue for immunohistochemistry, creating parallel storage and handling requirements. The authors say their protocol avoids hazardous solvents such as xylene and performed comparably to testing on fresh or frozen tissue. (journals.sagepub.com)

Why it matters: For veterinary diagnosticians, wildlife health teams, and labs supporting cervid surveillance, the study points to a more flexible way to test archived or suboptimally stored samples when fresh tissue isn’t available. That could help with retrospective investigations, discrepant ELISA/IHC cases, and surveillance in settings where cold-chain logistics are difficult. The findings also build on earlier Pennsylvania work showing RT-QuIC can perform strongly on retropharyngeal lymph nodes, and on a recent multi-laboratory comparison suggesting the assay is reproducible across participating U.S. labs, though RT-QuIC still is not the standard federally approved frontline surveillance test. (journals.sagepub.com)

What to watch: Watch for further validation, standardization, and any movement toward broader diagnostic or surveillance use of preserved-tissue RT-QuIC by wildlife and veterinary agencies. (pmc.ncbi.nlm.nih.gov)