Researchers Find CWD Proteins in Deer Semen

Mechanisms for transmission of CWD prions among captive or wild cervids are not fully understood. ( John Maday )

In research with potential implications for cervid breeders and wild herds, scientists have detected the presence of chronic wasting disease (CWD) prions in semen and sexual tissues of prion-infected whitetail deer bucks.

The team of researchers, from the University of Texas Health Science Center at Houston, Colorado State University and USDA/APHIS Veterinary Services published their findings in a report titled “In Vitro detection of Chronic Wasting Disease (CWD) prions in semen and reproductive tissues of white tailed deer bucks (Odocoileus virginianus),” in the online journal PLOS ONE.

In their report, the researchers note that mechanisms for transmission of CWD prions are not fully understood, and previous research has not explored the presence of the prions in semen or sexual tissues in deer.

The team collected post-mortem samples from  farmed pre-clinical, CWD positive WTD bucks, and analyzed them using Protein Misfolding Cyclic Amplification (PMCA) technology.

Overall CWD detection in these samples had a sensitivity of 59.3%, with a specificity of 97.2%. Results indicate high prevalence, 80 to 100% depending on the sample type, of CWD prions in male sexual organs and fluids in late stage, pre-clinical, CWD-infected deer. Improved PCMA technology with ultra-high sensitivity helped the researchers detect low levels of CWD prions in brain and lymph tissues, allowing them to identify animals with pre-clinical infections, and detect the prions in semen and sexual tissues.  

Previous studies have shown that infected animals can shed CWD prions into the environment through urine, feces and saliva. The researchers note that progressive accumulation of prions in the environment by shedding, carcasses decomposition and other tissue sources over time, coupled with the prion’s environmental persistence and resistance to degradation “make a compelling argument as to the role of the environment contamination in CWD transmission in both natural and captive settings.” They suspect though, that other mechanisms are involved, including sporadic CWD cases, translocation of the infectious agent by scavengers, vertical transmission from mother to offspring, and potentially, transmission through sexual contact.

Based on their results, the researchers confirmed the presence of CWD prions in semen and male sexual tissues in CWD-infected deer. They note a need for additional experiments in live deer to determine whether CWD can be transmitted by breeding practices including sexual contacts or artificial insemination. Managers of captive cervid herds commonly exchange semen between herds for use in their breeding programs.

Read the full report from the peer-reviewed, open-access journal PLOS ONE.

For more on CWD research, see these articles from BovineVetOnline:

Researchers developing new live-animal test for CWD

Cattle Resist CWD in Long-Term Trial

We Need a National Strategy for CWD

University of Calgary Vaccine Protects Against CWD