Cardone F, Thomzig A, Schulz-Schaeffer WJ, Valanzano A, Sbriccoli M, Abdel-Haq H, Graziano S, Puopolo M, Brown P, Beekes M, Pocchiari M (2009): PrPTSE in muscle-associated lymphatic tissue during the preclinical stage of mice orally-infected with BSE
J. Gen. Virol. 90 (10): 2563-2568. Epub 17 Jun.

The involvement of muscles in the pathogenesis of transmissible spongiform encephalopathies (TSE) is irregular and unpredictable. We show that the TSE-specific protein (PrP^TSE) is present in muscles of mice fed with a mouse-adapted strain of bovine spongiform encephalopathy (BSE) as early as 100 days post infection, corresponding to about one third of the incubation period. The proportion of mice with positive muscles and the number of muscles involved increased as infection progressed, but never attained more than limited distribution even at the clinical stage of disease. The appearance of PrP^TSE in muscles during the pre-clinical stage of disease was likely due to the haematogenous/lymphatic spread of infectivity from the gastro-intestinal tract to lymphatic tissues associated with muscles, whereas in symptomatic animals the presence of PrP^TSE in the nervous system, in neuromuscular junctions, and in muscle fibers suggests a centrifugal spread from the CNS as already observed in other TSE models.