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Evaluation of depth filtration to remove prion challenge from an immune globulin preparation
Author(s) -
Van Holten R. W.,
Autenrieth S. M.
Publication year - 2003
Publication title -
vox sanguinis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.68
H-Index - 83
eISSN - 1423-0410
pISSN - 0042-9007
DOI - 10.1046/j.1423-0410.2003.00312.x
Subject(s) - filtration (mathematics) , chromatography , chemistry , centrifugation , size exclusion chromatography , membrane , elution , sonication , ultrafiltration (renal) , antibody , scrapie , biology , biochemistry , prion protein , immunology , enzyme , disease , pathology , statistics , mathematics , medicine
Background and Objectives Plasma‐derived therapeutic proteins have the potential to contain transmissible spongiform encephalopathy (TSE) infectivity. This study evaluated the effectiveness and characterized the mechanism of abnormal prion protein removal during a depth‐filtration step used in the manufacture of an immunoglobulin preparation. Materials and Methods Scrapie brain homogenate was treated with lysolecithin, sonicated and sequentially filtered through 0·45‐, 0·22‐ and 0·1‐µm membrane filters. The scrapie brain homogenate was then added (at a 1 : 51 dilution) to the Supernatant III fraction used in the manufacture of Rh o (D) immune globulin (human). The spiked immunoglobulin preparation was then filtered through a depth filter under the same conditions used in full‐scale production. After filtration, the depth filter was washed with hypertonic NaCl solutions to elute the abnormal prion protein (PrP Sc ) from the filter. A Western blot assay for PrP Sc was used to quantify removal from the filtrate and recovery from the filter washes. A second run was performed whereby the PrP Sc ‐spiked Supernatant III was filtered through a 0·22‐µm membrane filter prior to depth filtration. A third run evaluated depth filtration of PrP Sc in Tris‐buffered saline (TBS). Results The depth filter removed greater than four logs of PrP Sc from the Supernatant III filtrate. A significant portion of the PrP Sc could be recovered from the depth filter by elution with high‐molarity NaCl solutions. Prefiltration (through a 0·22‐µm membrane filter) of the spiked Supernatant III prior to depth filtration removed all detectable PrP Sc . Depth filtration removed less than one log of PrP Sc from TBS. Conclusions Depth filtration appears to remove PrP Sc from the immunoglobulin preparation by mechanical straining rather than by adsorption to the filter matrix. The immunoglobulin preparation caused the PrP Sc to aggregate from particles < 0·1 µm in size to particles of > 0·22 µm, probably as a result of the presence of methanol in the preparation. The depth filter failed to remove PrP Sc from a purely aqueous environment.