Pall: Study shows filtration technology removes disease-carrying prions from blood for transfusions

By E. Janene Geiss

Philadelphia, Dec. 20 - Pall Corp. announced Tuesday that a study of its filtration technology demonstrated that it is effective in removing prions from blood.

Prions are the agent believed to cause a variety of fatal neurodegenerative diseases called transmissible spongiform encephalopathies (TSEs), including variant Creutzfeldt-Jakob disease (vCJD), the human form of "mad cow" disease, according to a company news release.

Variant CJD can be transmitted through blood transfusion years before an infected donor shows any symptoms of the disease, officials said.

The study showed that the filtration technology removes infectious scrapie prions. Scrapie is a TSE disease affecting sheep, officials said.

The studies were conducted and authored by Samuel Sowemimo-Coker, principal scientist and technical director of Pall Medical, in collaboration with scientists from the New York Institute for Basic Research, one of the world's leading prion research centers, officials said.

The study entitled "Removal of exogenous (spiked) and endogenous prion infectivity from red cells with a new prototype of leukoreduction filter," was published in the December issue of Transfusion, the official journal of the AABB.

The research focused on three approaches to evaluate the performance of the Pall prion reduction filter. In the exogenous (spiking) phase of the study, scrapie-infected brain homogenates were added to human red blood cells and then passed through a prion removal filter. The results showed that prions were removed below the level of detection by the Western blot assay, officials said.

In another phase of the exogenous study, scrapie-infected brain homogenates were diluted to obtain a variety of concentrations of infectious prion. These varying concentrations were divided into a test (filtered) group and a control (non-filtered) group and injected into the brains of healthy hamsters, the typical model used to determine prion removal efficiency. The results of this phase found that the prion reduction filter removed 3.7 logs, or more than 99.9%, of the infectious prion, officials said.

In the endogenous infectivity phase of the study, which is the most relevant to transfusion-transmitted TSEs, whole blood was collected from symptomatic scrapie-infected hamsters. It was processed into red blood cell samples that were designated either as test (filtered) or control (non-filtered) groups and then injected into healthy hamsters. Endogenously scrapie-infected red blood cells that were not filtered transmitted disease to six of the 43 animals, while the filtered red blood cells did not transmit disease to any of 35 animals, officials said.

The researchers concluded that the use of this type of filter should reduce the risk of vCJD transmission through blood transfusion.

"Transmission of vCJD by blood transfusion is a serious threat and prion reduction by filtration is a realistic and practical approach to minimize the risk," Sowemimo-Coker said in the release.

Protecting the blood supply from prions is a top priority since vCJD can be asymptomatic for many years and no one knows how many transfusion recipients may be receiving infected blood. There is no reliable test available to determine the presence of vCJD in blood, officials said. This past month, the British Department of Health announced that it must track down another 50 people who received a blood transfusion to notify them of potential exposure to vCJD.

Pall is an East Falls, N.Y., biotechnology company specializing in filtration, separations and purification for the pharmaceutical, biotechnology, transfusion medicine, semiconductor, water purification, aerospace and broad industrial markets.

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