Characterization of an unusual transmissible spongiform encephalopathy in goat by transmission in knock-in transgenic mice

Abstract

Bovine spongiform encephalopathy (BSE) is a fatal neurodegenerative disorder of cattle, and its transmission to humans through contaminated food is thought to be the cause of the variant form of Creutzfeldt–Jakob disease. BSE is believed to have spread from the recycling in cattle of ruminant tissue in meat and bone meal (MBM). However, during this time, sheep and goats were also exposed to BSE-contaminated MBM. Both sheep and goats are experimentally susceptible to BSE, and while there have been no reported natural BSE cases in sheep, two goat BSE field cases have been documented. While cases of BSE are rare in small ruminants, the existence of scrapie in both sheep and goats is well established. In the UK, during 2006–2007, a serious outbreak of clinical scrapie was detected in a large dairy goat herd. Subsequently, 200 goats were selected for post-mortem examination, one of which showed biochemical and immunohistochemical features of the disease-associated prion protein (PrPTSE) which differed from all other infected goats. In the present study, we investigated this unusual case by performing transmission bioassays into a panel of mouse lines. Following characterization, we found that strain properties such as the ability to transmit to different mouse lines, lesion profile pattern, degree of PrP deposition in the brain and biochemical features of this unusual goat case were neither consistent with goat BSE nor with a goat scrapie herdmate control. However, our results suggest that this unusual case has BSE-like properties and highlights the need for continued surveillance.