Submitted to: Letters in Applied Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/9/2007
Publication Date: 6/1/2007
Citation: Nicholson, E.M., Richt, J.A., Rasmussen, M.A., Hamir, A.N., Lebepe-Mazur, S, Horst, R.L. 2007. Exposure of sheep scrapie brain homogenate to rumen-simulating conditions does not result in a reduction of PrP**sc levels. Letters in Applied Microbiology. 44:631-636. Interpretive Summary: It has been established that adult cattle are less susceptible to the prion disease Bovine Spongiform Encephalopathy (BSE) than younger animals. One possible reason for this is developmental changes in the digestive tract, including development of a fully functioning rumen. In this work, we incubated prion infected sheep brain in rumen fluid from an adult cow. No apparent loss of infectious prions was observed indicating that the reduced susceptibility of adult cattle relative to younger cattle is unlikely to arise from the developmental changes in the rumen. This work addresses issues of susceptibility to BSE, a livestock disease with major effects on the cattle industry. Enhancing our understanding of the basic biology of the disease will better enable the design of countermeasures to prevent and control BSE and other prion diseases.
Technical Abstract: The abnormal form of the prion protein (PrP**Sc) is the causative agent of bovine spongiform encephalopathy (BSE) and other transmissible spongiform encephalopathies (TSEs). PrP**Sc resists most common disinfection procedures and appears to remain infectious under conditions used to render animal derived material for use in animal feed. Epidemiology of the BSE outbreak in the United Kingdom indicates younger animals were at higher risk of infection. The rumen undergoes pronounced developmental changes early in life coinciding with the introduction of fiber into the diet. The timeframe of highest risk of infection overlaps the time in life prior to full rumen development and as such, the fully functioning rumen may provide protection against BSE infection. Here we evaluate the effect of rumen-simulating conditions on PrP**Sc levels. No loss of PrP**Sc was observed over a 24 hour time period indicating that a fully developed rumen fermentation does not provide significant protection against prion infection via the oral route of infection.