Hidden Prions a Public Health Threat Say Experts

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Silent Infection with vCJD

BSE creates holes in the brains of infected cows: Image courtesy of the CDC

Although the barrier to developing clinical disease may be very large, the barrier to silent infection of the host…may be modest but not detectable by PrPsc or infectivity assays until prolonged periods….have elapsed,” according to  John Collinge ChB, MD in a recent Science magazine Perspective. “Healthy” people colonized with vCJD prions pose a risk to others through blood and tissue donation, explained Collinge who heads the Department of Neurodegenerative Disease at UCL institute of Neurology in London, and did not participate in the study. Moreover (because autoclaving isn’t hot enough to denature prions) they can also be passed from patient to patient on contaminated surgical instruments. Prions adapted to a new host are more deadly to others of the same species than they are to the original host, he warned.

Prions Spread Within Species and Across Species Barriers

Other prion-containing tissues, including muscle and blood, may similarly replicate prions with an expanded host range with profound implications for the facile spread of CWD, BSE and vCJD within and across species barriers,” commented Mark Zabel, PhD, from Colorado State University in Fort Collins, who was not involved in this study.

The Béringue study demonstrates that different prion strains may not only have preference for certain species but also for certain tissues within the same species,” he told this writer, and suggested that lymphoid and nervous systems use different mechanisms or receptors that preferentially capture distinct prion strains, “a hypothesis supported by the expanded host range of splenic prions compared to brain prions in this study.

Why a More Aggressive Search for Prions is So Important

It now appears that not only is the transmission barrier keeping these odd pathogenic proteins from easily jumping to you from that steak on your plate more porous than previously thought, it also seems that authorities might not always be testing the right tissue. As William A. Rutala PhD and David J. Weber MD point out in their 2010 paper: “Prion diseases elicit no immune response, result in a pathologic process confined to the central nervous system, have an incubation period of years, and usually are fatal within 1 year after diagnosis.” These are not diseases to be treated casually.

Sources:

Vincent Béringue, PhD and Mark Zabel, PhD: Personal interviews.

Béringue, V., Herzog, L., Jaumain, E. et al. Facilitated Cross-Species Transmission of Prions in Extraneural Tissue. (2012). Science. 335: pp. 472-475. Accessed February 23, 2012.

Collinge, J. The Risk of Prion Zoonoses. (2012). Science. 335: pp. 411-413. Accessed February 23, 2012.

Moreno-Gonzalez I., and Soto C. Misfolded protein aggregates: mechanisms, structures and potential for disease transmission. (2011). Seminars in Cell & Developmental Biology; 5: pp.282-287. Accessed February 23, 2012.

Rutala WA, Weber DJ. Guideline for Disinfection and Sterilization of Prion-Contaminated Medical Instruments. (2010). Infection Control and Hospital Epidemiology: 31; pp. 107-117. Accessed February 24, 2012.

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