Real-time quaking-induced conversion detection of pathological prion protein in skeletal muscle, nasal and neural tissues of cattle with natural L-BSE

Introduction Bovine spongiform encephalopathy (BSE) includes classical BSE (C-BSE) and two atypical forms, high-type (H-BSE) and low-type (L-BSE). Compared with C-BSE, the peripheral distribution and tissue tropism of atypical BSE remain poorly characterized. The apparent spontaneous occurrence of atypical BSE and its potential food safety implications highlight the need for highly sensitive surveillance methods. This study aimed to develop and standardize real-time quaking-induced conversion (RT-QuIC) protocols to investigate PrPSc-associated seeding activity in skeletal muscle, nasal, and neural tissues of cattle naturally affected by L-BSE. Methods Brain, spinal cord, skeletal muscle, and olfactory tissues were collected from naturally affected Italian cattle and analyzed using RT-QuIC to detect PrP Sc -associated seeding activity. Results Seeding activity was detected in skeletal muscle and olfactory tissues, as well as in the brain and spinal cord, suggesting the involvement of neuromuscular and olfactory tissues in L-BSE. Discussion Consistent with previous experimental observations, the detection of seeding activity in skeletal muscle raises the possibility that this tissue may contribute to L-BSE-associated infectivity, although RT-QuIC results alone cannot establish tissue infectivity. These findings highlight the importance of highly sensitive BSE surveillance in cattle intended for slaughter to facilitate the early detection of atypical BSE cases and minimize potential food safety risks.