Species Susceptibility Assay for Chronic Wasting Disease

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DESCRIPTION (provided by applicant): Like rabies, chronic wasting disease (CWD) is a fatal infectious disease with a wildlife reservoir. Strategies to combat CWD and other wildlife prion diseases will require a combination of active surveillance and wildlife control measures. The identification of species susceptible to CWD is of particular importance because, while the mode of transmission in the wild remains unknown, it is not possible to predict the likely impact of the current epidemic. In the brains of humans and animals affected by prion diseases, a cellular glycoprotein termed PrPc converts into n protease-resistant pathogenic isoform called PrPsc. In our laboratory, we have focused on developing a novel method that can be conveniently used for susceptibility testing in a variety of prion diseases. This method amplifies PrPsc levels in prion-infected tissue homogenates biochemically in the presence of normal brain tissue containing PrPc. We have successfully amplified PrPsc>10-fold in brain membrane preparations biochemically without detergents or harsh physical disruption of cellular constituents. Consistent with the characteristics of PrPc conversion to PrPsc in vivo, our method of PrPsc amplification is prion-specific, and depends upon time, pH, and temperature. Significantly, the degree of PrPsc amplification in vitro correlates with the susceptibility of a specific animal species to prion infection in vivo. Furthermore, we have successfully amplified PrPsc from four different prion strains derived from two animal species. We now propose to test the hypothesis that non-cervid species might be susceptible to CWD infection or subclinical carriage. In partnership with the Dartmouth Hitchcock Medical Center, New Hampshire Fish and Game Authority, and New Hampshire State Veterinary Diagnostic Laboratory, we propose to use in vitro PrPsc amplification to measure the potential susceptibility of a range of potential host species to CWD as well as scrapie. Species to be tested include humans, cows, pigs, sheep, goats, chickens, dogs, cats, coyotes, foxes, raccoons, fisher cats, hares, and deer mice. The results of this work will efficiently identify species potentially susceptible to CWD and scrapie and help facilitate public health surveillance and control efforts for North American prion diseases.