Ticks harbor and excrete chronic wasting disease prions

H. N. Inzalaco; F. Bravo-Risi; R. Morales; D. P. Walsh; D. J. Storm; J. A. Pedersen; Wendy Christine Turner; S. S. Lichtenbergh

doi:10.1038/s41598-023-34308-3

USGS · 70257339

Ticks harbor and excrete chronic wasting disease prions

H. N. Inzalaco·F. Bravo-Risi·R. Morales·D. P. Walsh·D. J. Storm·J. A. Pedersen·Wendy Christine Turner·S. S. Lichtenbergh

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Abstract

Chronic wasting disease (CWD) is a fatal neurodegenerative disease caused by infectious prions (PrP CWD ) affecting cervids. Circulating PrP CWD in blood may pose a risk for indirect transmission by way of hematophagous ectoparasites acting as mechanical vectors. Cervids can carry high tick infestations and exhibit allogrooming, a common tick defense strategy between conspecifics. Ingestion of ticks during allogrooming may expose naïve animals to CWD, if ticks harbor PrP CWD . This study investigates whether ticks can harbor transmission-relevant quantities of PrP CWD by combining experimental tick feeding trials and evaluation of ticks from free-ranging white-tailed deer ( Odocoileus virginianus ). Using the real-time quaking-induced conversion (RT-QuIC) assay, we show that black-legged ticks ( Ixodes scapularis ) fed PrP CWD -spiked blood using artificial membranes ingest and excrete PrP CWD . Combining results of RT-QuIC and protein misfolding cyclic amplification, we detected seeding activity from 6 of 15 (40%) pooled tick samples collected from wild CWD-infected white-tailed deer. Seeding activities in ticks were analogous to 10–1000 ng of CWD-positive retropharyngeal lymph node collected from deer upon which they were feeding. Estimates revealed a median infectious dose range of 0.3–42.4 per tick, suggesting that ticks can take up transmission-relevant amounts of PrP CWD and may pose a CWD risk to cervids.

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Source-reported bounding extent: 42.49192° to 47.07757° latitude; -92.888035° to -86.805415° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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H. N. Inzalaco, F. Bravo-Risi, R. Morales, D. P. Walsh, D. J. Storm, J. A. Pedersen, Wendy Christine Turner, S. S. Lichtenbergh. 2023-05-15. Ticks harbor and excrete chronic wasting disease prions. https://doi.org/10.1038/s41598-023-34308-3

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