Shari Spector

Increasing the capacity of parvovirus-retentive membranes : performance of the Viresolve Prefilter

Removal of small parvoviruses from highly purified proteins can be performed using normal‐flow filters. The entrapment of protein aggregates, denatured proteins and other impurities can cause plugging and a decrease in filter capacity. In the present study a variety of prefilters were investigated for their ability to remove the species that foul Viresolve™ NFP (normal‐flow parvovirus) filters. The Viresolve™ Prefilter, which utilizes entrapped diatomaceous earth to hydrophobically bind fouling species, provided a dramatic increase in virus filter capacity for solutions containing human IgG or a variety of monoclonal antibodies. We found that the component of the human IgG stream that bound to the Prefilter, when analysed using SDS/PAGE, isoelectric‐focusing, size‐exclusion chromatography, CD and ANS (1‐anilinonaphthalene‐8‐sulphonate) titration, consisted of monomeric IgG variants containing more exposed hydrophobic surfaces. The bound component may represent oxidized or otherwise degraded IgG species or a subset of IgG molecules with more hydrophobic antigen‐binding surfaces. The results indicate that NFP membranes do not foul solely as a result of entrapment of protein aggregates in the pore structure. The Viresolve™ Prefilter has a high permeability, did not diminish protein yield and provided consistent performance between different media lots, device lots and device scales.