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 phage PP7, 25 nm) were used to determine the ability of a newly developed, modified polyvinylidene fluoride (PVDF) membrane filter to remove viruses from several fluids. These included ultrapure water, Dulbecco's modified Eagle minimum essential medium (DMEM) and DMEM with 10% fetal bovine serum (DMEM-10). Small volume (10 ml) filtration experiments were done with 47-mm disks while larger volumes (1 litre) were done with virus suspended in DMEM-10, using cartridge filters with a surface area of 1.63 m2. With 47-mm disks, influenza A virus and phage T1 were removed to below detectable limits in all fluids tested (titre reduction [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 greatest concentration of phage PP7 and poliovirus was removed from ultrapure water (phage PP7, Tr = 2.1 x 10(7); poliovirus, TR > 3.2 x 10(4), while the removal efficiency from DMEM-10 was substantially lower (phage PP7, Tr = 2.3; poliovirus, Tr = 2.1 x 10(2)). Results of cartridge challenges in DMEM-10 were comparable to the corresponding small disk 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 separate experiments, the recovery of purified albumin (69,000 Da) and IgG (150,000 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 suggest potential applications of this membrane filter, when protection against adventitious viral contaminants is desired.