Immunolabelling of non-phosphorylated neurofilament indicates damage of spinal cord axons in TSE-infected goats

TRANSMISSIBLE spongiform encephalopathies (TSEs) including bovine spongiform encephalopathy (BSE) are devastating neurodegenerative disorders caused by conversion of the normal cellular prion protein (PrPC) into an abnormal isoform (PrPSc; Prusiner, 1982, Chesebro, 2003). Following the discovery of goat BSE cases in the UK and France (Eloit and others 2005, Jeffrey and others 2006, Spiropoulos and others 2011) small ruminants were considered to pose a BSE infection risk/source for cattle, and human beings in particular. In goats experimental TSE susceptibility strongly depends on polymorphisms in the prion protein gene (PRNP) (Aguilar-Calvo and others 2014, 2015, Lacroux and others 2014). In particular, goats with R/Q211 polymorphism (IQQ/IRQ; single-letter amino acid code) and Q/K222 polymorphism (IRK/IRQ) show delayed or even absent clinical signs compared with wild-type goats (IRQ/IRQ) (Aguilar-Calvo and others 2015). After oral infection of ruminants, the agent is shown to spread among others via the autonomous nervous system, ultimately resulting in manifested disease in the brain and spinal cord (van Keulen and others 2002, Hoffmann and others 2007, Kaatz and others 2012). So far however, little attention has been paid to the cellular and molecular mechanisms that facilitate the spread of prions within the nervous system as well as to the involvement of the spinal cord in the pathogenesis of TSEs, even though PrPSc has been detected in this part of the nervous tissue (Flechsig and others 2000, Fukuda and others 2012, Kaatz and others 2012).