ABSTRACT
Nanofiltration is incorporated into the manufacturing processes of many protein biopharmaceuticals to enhance safety by providing the capacity to retain pathogens while allowing protein drugs to pass through the filter. Retention is mainly a function of size; however, the shape of the pathogen may also influence retention. The ability of the Viresolve(®) Pro nanofilter to remove different sized viruses during the manufacture of a Coagulation Factor IX (Alphanine(®) SD) was studied at varying ionic strength, a process condition with the potential to affect virus shape and, hence, virus retention. Eight viruses were tested in a scale-down of the nanofiltration process. Five of the viruses (EMCV, Reo, BVDV, HIV, PRV) were nanofiltered at normal sodium processing conditions and three (PPV, HAV and WNV) were nanofiltered at higher and lower sodium. Representative Reduction Factors for all viruses were ≥4.50 logs and removal was consistent over a wide range of ionic strength.
Subject(s)
Factor IX/isolation & purification , Ultrafiltration/methods , Viruses/isolation & purification , Biological Products/isolation & purification , Drug Contamination/prevention & control , Humans , Micropore Filters , Nanotechnology , Osmolar Concentration , Particle Size , Viruses/ultrastructureABSTRACT
Nanofiltration assures that protein therapeutics are free of adventitious agents such as viruses. Nanofilter pores must allow passage of protein drugs but be small enough to retain viruses. Five nanofilters have been evaluated to identify those that can be used interchangeably to yield a high purity Coagulation Factor IX product. When product preparations prior to nanofiltration were analyzed using electrophoresis, Western blot, liquid chromatography - tandem mass spectrometry and size exclusion HPLC, factor IX, inter - α - trypsin inhibitor and C4b binding protein (C4BP) were observed. C4BP was removed from product by all five nanofilters when nanofiltration was performed at physiological ionic strength. However, at high ionic strength, C4BP was removed by only two nanofilters. HPLC indicated that the Stokes radius of C4BP was larger at low ionic strength than at high ionic strength. The results suggest that C4BP exists in an open conformation at physiological ionic strength and is removed by nanofiltration whereas, at high ionic strength, the protein collapses to an extent that allows passage through some nanofilters. Manufacturers should be aware that protein contaminants in other nanofiltered protein drugs could behave similarly and conditions of nanofiltration must be evaluated to ensure consistent product purity.
