Chronic Wasting Disease (CWD) is a prion disease that primarily affects cervids, such as white-tailed deer, mule deer, and elk. Recently, concerns have been raised about the zoonotic potential of CWD, leading researchers to investigate the possibility of transmission to humans. While other prion diseases, such as bovine spongiform encephalopathy, have been known to infect humans and cause fatal neurodegenerative conditions like variant Creutzfeldt-Jakob disease (CJD), the transmission of CWD to humans remains uncertain.
A recent study conducted by researchers at the National Institute of Allergy and Infectious Diseases (NIAID) and Rocky Mountain Laboratories aimed to assess the infectivity of CWD in human cerebral organoids. Organoids exposed to high concentrations of CWD inocula from different cervid species were monitored for up to 6 months. Despite prolonged exposure, the human organoids remained uninfected with CWD, indicating a strong species barrier that prevents transmission to humans.
The study results are supported by previous research that showed no evidence of CWD transmission to macaques, but suggested possible susceptibility in squirrel monkeys. Furthermore, the researchers observed no propagation of CWD or deposition of protease-resistant forms of human prions in the exposed organoids. This failure to infect human neural tissue with CWD prions highlights the significant species barrier that exists between cervids and humans.
While the study provides valuable insights into the infectivity of CWD in humans, researchers acknowledge the need for continued vigilance. Although the data suggest a low risk of CWD transmission to humans, the possibility cannot be ruled out entirely. Further research is needed to better understand the mechanisms of prion transmission and the potential for cross-species infection. By studying the genetic and molecular characteristics of prions, researchers can improve our ability to assess the risks of zoonotic transmission and develop effective prevention strategies.
The study findings suggest a robust species barrier that protects humans from CWD infection. Despite the high infectivity of CWD prions and their ability to infect other animal species, human cerebral organoids did not support the propagation of CWD prions. This research contributes to our understanding of prion diseases and highlights the importance of continued surveillance and research to safeguard human health.
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