Good news about chronic wasting disease

Mule deer Chronic wasting disease (CWD) is a prion disease affecting wild and captive deer. Like all mammalian prion diseases, which include Creutzfeldt-Jakob disease (CJD), kuru and variant CJD (vCJD) in humans and bovine spongiform encephalopathy (BSE) in cattle, the central event in CWD infection is the post-translational conversion of the host-encoded, cellular prion protein (PrPC), to an abnormal form called PrPSc. Progressive accumulation of PrPSc in the central nervous system is associated with clinical signs of CWD which includes weight loss, behavioural changes, excessive salivation, difficulty swallowing and ataxia prior to death. International concern over CWD is growing as infected cervids have now been reported in fourteen states in North America, two Canadian provinces and in South Korea. To date, CWD has not been reported in Europe, although surveillance has been limited.

The negative transmission data reported in this paper support the conclusion that the transmission barrier associated with the interaction of human PrP and these CWD prions is greater than that associated with interaction of human PrP and the prion strain causing epizootic BSE in cattle. This is good news from a human health perspective, but further studies will be required to evaluate the transmission properties of distinct deer prion strains as they are characterized.

Chronic wasting disease prions are not transmissible to transgenic mice over-expressing human prion protein. J Gen Virol. Jul 7 2010
Chronic wasting disease (CWD) is a prion disease that affects free-ranging and captive cervids, including mule deer, white-tailed deer, Rocky Mountain elk, and moose. CWD-infected cervids have been reported in fourteen US states, two Canadian provinces and in South Korea. The possibility of a zoonotic transmission of CWD prions via diet is of particular concern in North America where hunting of cervids is a popular sport. To investigate the potential public health risks posed by CWD prions, we have investigated whether intracerebral inoculation of brain and spinal cord from CWD-infected mule deer transmits prion infection to transgenic mice over-expressing human prion protein with methionine or valine at polymorphic residue 129. These transgenic mice have been utilised in extensive transmission studies of human and animal prion disease and are susceptible to BSE and vCJD prions, allowing comparison with CWD. Here we show that these mice proved entirely resistant to infection with mule deer CWD prions arguing that the transmission barrier associated with this prion strain/host combination is greater than that observed with classical BSE prions. However, it is possible that CWD may be caused by multiple prion strains; further studies will be required to evaluate the transmission properties of distinct cervid prion strains as they are characterised.

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