Exploring the possibility of CWD transmission through artificial insemination of semen from CWD positive bucks

Authors: Cassmann, Eric; Greenlee, Justin

Submitted to: North American Deer Farmer
Publication Type: Trade Journal
Publication Acceptance Date: 7/1/2022
Publication Date: 7/20/2022
Citation: Cassmann, E.D., Greenlee, J.J. 2022. Exploring the possibility of CWD transmission through artificial insemination of semen from CWD positive bucks. North American Deer Farmer. p. 107-109.

Interpretive Summary:

Technical Abstract: Artificial insemination is a popular method for herd management and reproduction in the cervid farming industry. There are numerous benefits including increased access to superior genetics, convenience, and increased farm revenue. In this article, we summarize the research that is underway to determine if semen from a CWD infected buck can transmit the disease. Some research has already been performed on the reproductive transmission of CWD in cervids. Scientists from Colorado State University used Muntjac deer to demonstrate that CWD positive does could transmit CWD to their fawns (1). In the study, Muntjac does were bred to CWD negative bucks. At the time of breeding, does were either in the early or late stage of CWD infection. Fawns from both doe groups were positive for CWD. More recent laboratory experiments on semen from CWD positive bucks have demonstrated the presence of CWD prions (2). Researchers used an amplification technique called PMCA (protein misfolding cyclic amplification). The technique amplifies low levels of CWD prions to a point where conventional antibody methods can detect them. The caveat to the discovery of CWD prions in semen is that we’re unsure if the amount of CWD prions in semen is biologically relevant. In other words, is the level of CWD prions in semen sufficient to be infectious and cause disease in deer? In our present study, we are trying to answer that question. We obtained semen from a CWD positive buck. The semen was confirmed to be PMCA positive. For the study, we used the transcervical insemination method in three does. As of June 19th, a single fawn was born. Shortly after birth the fawn was separated to prevent environment CWD exposure. We are assessing both the does and the fawn for the development of CWD. The experiment is expected to last several years, and periodic sampling will help monitor progress. A second phase of the study will investigate the absolute susceptibility of white-tailed deer does to CWD after transcervical and/or vaginal exposure to large amounts of CWD prions. We plan to expose two does to brain suspension from a CWD positive deer. These does will also be monitored long term for the development of disease. If these does remain negative, it would indicate that CWD transmission to the dam is highly unlikely via reproductive tract exposure.