US and Nordic researchers, in a paper late last week in Emerging Infectious Diseases, describe a novel chronic wasting disease (CWD) prion strain from a moose in Finland that's distinct not only from CWD prions in North America but also from those in neighboring Norway.
Scientists from Colorado State University and their colleagues in Finland and Norway analyzed a CWD isolate from a female moose identified as being sick in the wild and later found dead in 2018. They compared the isolate to those from a US moose and elk with CWD and from three CWD-infected moose from Norway.
This finding adds to an increasing body of evidence for a surprising variety of strains among Nordic cervids.
CWD is an always-fatal disease spreading in members of the deer family (cervids). It has yet to be identified in people, but experts believe that it could make that jump, similar to what happened with bovine spongiform encephalopathy, or "mad cow" disease, another prion infection. Prions are misfolded proteins.
The researchers found that the Finnish CWD strain shared certain characteristic to the isolates from Norway, such as spreading efficiently in mice that had been genetically modified to experimentally react to prions more like cervids do. But mouse studies showed that disease onset and progression, the way the CWD prion affected the nervous system, and other factors, were different. And differences were even greater when comparing the moose isolate from Finland with those from the United States.
The authors conclude, "This finding adds to an increasing body of evidence for a surprising variety of strains among Nordic cervids, which stands in contrast to the relatively consistent CWD strain profile among North America deer, elk, and moose. As yet, there appears to be no clear explanation for this diversity of Nordic CWD strains or insights into their origins."