Pathogenesis of chronic wasting disease in cervidized transgenic mice

Chronic wasting disease (CWD) is a fatal, endemic prion disease of wild and captive cervids, including deer, elk, and moose. Typical of prion diseases, CWD is characterized by the conversion of the native, protease-sensitive protein PrP^C to a protease-resistant isoform, denoted as PrP^RES. Here we have studied the expression of cervid PrP^C and the pathogenesis of CWD infection in transgenic mice expressing the normal cervid prion protein (Tg[CerPrP] mice). Using tissue-based in situ immunohistochemistry protocols, we first identified cervid PrP^C expression in the lymphoid, nervous, hemopoietic, endocrine, and certain epithelial tissues of Tg[CerPrP] mice. Tg[Cer-PrP] mice were then inoculated with CWD via one of four routes (intracerebral, intravenous, intraperitoneal, or oral); all groups developed spongiform encephalopathy, although the oral route required a larger infecting dose. Incubation periods were 184 ± 13, 218 ± 15, 200 ± 7, and 350 ± 27 days after inoculation, respectively. In longitudinal studies, we tracked the appearance of PrP^RES in the brain, spleen, Peyer's patches, lymph nodes, pancreatic islets of Langerhans, bone marrow, and salivary glands of preclinical and terminal mice. In addition, we documented horizontal transmission of CWD from inoculated mice and to un-inoculated cohabitant cage-mates. This work documents the multiroute susceptibility, pathogenesis, and lateral transmission of CWD infection in Tg[CerPrP] mice, affirming this model as a robust system to study this cervid transmissible spongiform encephalopathy.