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The use of a microporous polyvinylidene fluoride (PVDF) membrane filter to separate contaminating viral particles
K H Oshima1, T T Evans-Strickfaden, A K Highsmith
1Biological Products Branch, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
Abstract:
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.
Insights
This study shows a new polyvinylidene fluoride (PVDF) membrane filter effectively removes viruses larger than 50 nm from fluids. Smaller viruses were also removed, with efficiency varying by virus and fluid type.
Area of Science:
- Biotechnology
- Materials Science
- Virology
Background:
- Viral contamination poses a significant risk in various fluid applications.
- Effective filtration methods are crucial for removing viral agents.
- Polyvinylidene fluoride (PVDF) membranes are widely used but their viral removal efficiency can vary.
Purpose of the Study:
- To evaluate the efficacy of a newly developed, modified PVDF membrane filter for viral removal.
- To assess the filter's performance across different fluid types and viral sizes.
- To determine the recovery rate of proteins using the modified PVDF membrane.
Main Methods:
- Filtration experiments using various viral agents (influenza A virus, phage T1, PP7, poliovirus) and fluids (ultrapure water, DMEM, DMEM-10).
- Utilized both small volume (47-mm disks) and large volume (1.63 m² cartridge) filtration setups.
- Protein recovery (albumin, IgG) was assessed in separate experiments to evaluate membrane compatibility.
Main Results:
- The modified PVDF membrane filter demonstrated high efficacy (titre reduction [Tr] > 10(6)) in removing viral particles > 50 nm.
- Influenza A virus and phage T1 were removed to below detectable limits across all tested fluids.
- Removal of smaller viruses (phage PP7, poliovirus) was fluid-dependent, with higher efficiency in ultrapure water compared to DMEM-10.
- Protein recovery (albumin, IgG) exceeded 90%, indicating minimal loss of biomolecules.
Conclusions:
- The modified PVDF membrane filter is highly effective for removing larger viral particles (> 50 nm).
- The filter shows consistent removal of smaller viruses, though efficiency is influenced by fluid composition.
- High protein recovery alongside efficient virus retention suggests potential applications in bioprocessing where adventitious viral contamination is a concern.