Cellulose-based virus-retentive filters: a review

Abstract

Viral filtration is a critical step in the purification of biologics and in the monitoring of microbiological water quality. Viral filters are also essential protection elements against airborne viral particles. The present review first focuses on cellulose-based filter media currently used for size-exclusion and/or adsorptive filtration of viruses from biopharmaceutical and environmental water samples. Data from spiking studies quantifying the viral filtration performance of cellulosic filters are detailed, i.e., first, the virus reduction capacity of regenerated cellulose hollow fiber filters in the manufacturing process of blood products and, second, the efficiency of virus recovery/concentration from water samples by the viradel (virus adsorption-elution) method using charge modified, electropositive cellulosic filters or conventional electronegative cellulose ester microfilters. Viral analysis of field water samples by the viradel technique is also surveyed. This review then describes cellulose-based filter media used in individual protection equipment against airborne viral pathogens, presenting innovative filtration media with virucidal properties. Some pros and cons of cellulosic viral filters and perspectives for cellulose-based materials in viral filtration are underlined in the review.

Keywords: Adsorption–elution method; Cellulose filter media; Filtering facepieces; Viral clearance; Virus filtration.

Fig. 1

A typical monoclonal antibody recovery process. Taken from Liu et al. (2010)

Fig. 2

The separation spectrum for filtration membranes. Adapted from Fröhlich et al. (2012)

Fig. 3

Schematic representation of the void pore structure of regenerated cellulose hollow fibers used in Planova filters. Adapted from Makino et al. (1994)

Fig. 4

Cross sectional micrograph of Planova (20N model) hollow fiber wall. Taken from Hongo-Hirasaki (2006)

Fig. 5

Relative survivability^a (RS) of MS2 viruses on filters^b treated with different concentrations of DAS suspension. Error bars (n = 3) are shown. Taken from Woo et al. (2012). ^aRatio of the virus survival factor in the treated filter to that in the untreated filter, where the virus survival factor in a filter is the number of viruses recovered by elution from the filter divided by the number of viruses removed by the filtration process. ^b PF PP filter from commercial surgical mask (DuPont™ 01361N), CCF coarse pore cellulose filter paper (Whatman™ Grade 54, 22 μm pore size), FCF fine pore cellulose filter paper (Whatman™ Grade 50, 2.7 μm pore size)