THE USE OF A MICROPOROUS POLYVINYLIDENE FLUORIDE (PVDF) MEMBRANE-FILTER TO SEPARATE CONTAMINATING VIRAL PARTICLES FROM BIOLOGICALLY IMPORTANT PROTEINS

Viral agents (influenza A virus, 80-120 nm; phage T1, 50 nm head, 150 nm head, 150 nm tail; phage PR772, 53 nm; poliovirus, 28-30 nm; and ph age PP7, 25 nm) were used to determine the ability of a newly develope d, modified polyvinylidene fluoride (PVDF) membrane filter to remove v iruses from several fluids. These included ultrapure water, Dulbecco's modified Eagle minimum essential medium (DMEM) and DMEM with 10% feta l bovine serum (DMEM-10). Small volume (10 ml) filtration experiments were done with 47-mm disks while larger volumes (1 litre) were done wi th virus suspended in DMEM-10, using cartridge filters with a surface area of 1.63 m(2). With 47-mm disks, influenza A virus and phage T1 we re removed to below detectable limits in all fluids tested (titre redu ction [Tr] >2.0 x 10(6) and >5.8 x 10(8), respectively). The retention of phage PP7 and poliovirus was consistent but fluid dependent. The g reatest concentration of phage PP7 and poliovirus was removed from ult rapure water (phage PP7, Tr = 2.1 x 10(7); poliovirus, TR >3.2 x 10(4) ), while the removal efficency from DMEM-10 was substantially lower (p hage PP7, Tr = 2.3; poliovirus, Tr = 2.1 x 10(2)). Results of cartridg e challenges in DMEM-10 were comparable to the corresponding small dis k challenges. These results demonstrate that this PVDF membrane filter was very effective (Tr >10(6)) in removing viral particles (>50 nm); smaller viruses (<50 nm) were also consistently removed, but the level of removal depended on the virus and type of fluid tested. In separat e experiments, the recovery of purified albumin (69 000 Da) and IgG (1 50 000 Da) in the filtrate was also determined at approx. 0.015 mg/ml and approx. 10 mg/ml. Recovery of albumin and IgG was >90%. Efficient virus retention coupled with high recovery of protein <150 000 Da sugg est potential applications of this membrane filter, when protection ag ainst adventitious viral contaminants is desired. (C) 1996 The Interna tional Association of Biological Standardization