Removal of influenza A virus, phage T1, and PP7 from fluids with a nylon 0.04‐μM membrane filter

Abstract

We tested the ability of a 0.04‐μm nylon membrane filter to remove viral agents (influenza A virus, 80–120 nm; phage T1, 50–150 nm; and phage PP7, 25 nm) from the following media: ultrapure water (UPW), Dulbecco's modified Eagle minimum essential medium (DMEM), gelatin phosphate (GP), DMEM with 10% (DMEM‐10) fetal bovine serum (FBS), and 100% FBS. When challenged with at least 3.0 × 107 plaque‐forming units/mL, no influenza A virus was detected downstream of the filter with any of the fluids tested. The titer reduction (Tr) was determined using the equation: . Higher concentrations of phage T1 were removed from UPW (Tr = 1.6 × 106) and DMEM (Tr = 1.1 × 106) than from GP (Tr = 9.3 × 103), DMEM‐10 (Tr = 1.5 × 102), and 100% FBS (Tr = 2.4 × 102). Phage PP7 was removed in significant numbers only in ultrapure water (Tr = 8.5 × 104). The results indicate that adsorption enhanced the titer reduction in fluids containing low levels of protein. The titer reduction in DMEM‐10 and 100% FBS may reflect the sieving properties of the 0.04‐μm filter. As expected, a much smaller Tr was observed in the filtrate of the 0.2‐μm filters, compared to the 0.04 μm filters. In contrast to the 0.04‐μm filter, no increase in Tr was detected when the 0.2‐μm filters were challenged with virus diluted in UPW compared with virus diluted in GP. These results suggest that the 0.04‐μm filter has greater adsorptive properties than the 0.2‐μm filter. © 1994 by John Wiley & Sons, Inc..