Vertical transmission of chronic wasting disease in free-ranging white-tailed deer populations.

Chronic wasting disease (CWD) is a fatal neurodegenerative disease affecting cervids across North America, Northern Europe, and Asia. Disease transmission among cervids has historically been attributed to direct animal-to-animal contact with 'secreta' (saliva, blood, urine, and feces) containing the infectious agent, and indirect contact with the agent shed to the environment in these bodily components. Mounting evidence provides another mechanism of CWD transmission, that from mother-to-offspring, including during pregnancy (vertical transmission). Here we describe the detection of the infectious CWD agent and prion seeding in fetal and reproductive tissues collected from healthy-appearing free-ranging white-tailed deer (Odocoileus virginianus) from multiple U.S. states by mouse bioassay and in vitro prion amplification assays. This is the first report of the infectious agent in multiple in utero derived fetal and maternal-fetal reproductive tissues, providing evidence that CWD infections are propagated within gestational fetal tissues of white-tailed deer populations. This work confirms previous experimental and field findings in several cervid species supporting vertical transmission as an additional mechanism of CWD transmission and may help to further explain the facile dissemination of this disease among captive and free-ranging cervid populations.