Continuing the industry-leading work in the area of plasma purification processes, Bayer Biological Products (BP) scientists reported the capacity to remove the pathogenic form of human prion protein during plasma protein manufacture simulations.

In an abstract presented at the XXV International Congress of the World Federation of Hemophilia (WFH) in Seville, Spain, Bayer BP scientists shared data showing the prion protein that causes variant Creutzfeld-Jakob Disease (vCJD) can be removed by purification processes used in the manufacture of blood protein products, reducing the theoretical risk of transmission through use of these products.

The Western blot assay, quicker and cheaper than conventional bioassays, was licensed to BioReliance Corporation so other manufacturers of biological products could more quickly and efficiently assess manufacturing processes for prion protein removal. This research is the next step in a series of advancements reported by Bayer BP scientists over the last several months. Key to this work is the continued demonstration that the Western blot assay, developed by Bayer BP, used for detecting pathogenic prion proteins, is valuable in estimating the removal of TSE infectivity.

"Bayer remains committed to further increasing our ability to ensure all our biological products are safe from any theoretical threat posed by prions," said Dr. Gunnar Riemann, executive vice president, Bayer Corporation, and president, Bayer BP Business Group. "When patients receive a Bayer BP product, we want them to have peace of mind, knowing this is the safest product available."

The lead author on the abstract, Chris Stenland, Ph.D., senior scientist, Bayer BP, participated with other clinical, regulatory, and scientific experts, in a symposium held May 20 during the WFH congress titled "Where Do We Stand on vCJD: An Up to the Minute Look at vCJD and Clotting Factor Concentrates."

"Although no cases of variant CJD or other transmissible spongiform encephalopathies have been reported from use of therapeutic plasma proteins, we remain diligent in our work to prevent this possibility," said Dr. Stenland. "The results from our studies demonstrate that plasma manufacturing processes have a significant potential to remove these prions."

The pathogenic form of prion proteins (PrPs) has been associated with fatal diseases, including mad cow disease in cattle, scrapie in sheep, and the human disorders Creutzfeldt-Jakob Disease (CJD), Gerstmann-Straussler- Scheinker, Kuru, and fatal familial insomnia. To date, no clinical evidence exists to support the transmission of human transmissible spongiform encephalopathies (TSE), such as CJD, by blood or blood-derived products. However, recent evidence from experimental animal models suggests that blood has the potential to contain TSE infectivity and cross-species transmission may occur. For these reasons, biopharmaceuticals, including human plasma derivatives, recombinant proteins grown in media containing fetal calf serum, and human-derived products containing bovine additives, have a hypothetical risk of containing TSE infectivity, increasing the importance of continued advancements in this field of research. Bayer scientists are working toward reducing this theoretical risk for transmission even further.

Regulatory agencies require manufacturers to demonstrate removal or inactivation of pathogen impurities, such as viruses, from biological products. Although agencies currently do not require documentation of prion protein or TSE removal, they continue to follow the science in this area closely. Moreover, because methods that effectively inactivate the infectious TSE agent also destroy most soluble therapeutic proteins, the removal of prions remains the most viable strategy for addressing the hypothetical risk of TSE transmission. Assessing the ability of a particular manufacturing process to remove pathogenic prions is an important step in addressing this hypothetical risk. The methodology developed by Bayer allows researchers to quickly evaluate whether a particular manufacturing process is capable of removing TSE infectivity.