Removal of neutralized model parvoviruses and enteroviruses in human IgG solutions by nanofiltration

Abstract

BACKGROUND: Nanofiltration has proven to be an effective technology for virus removal. The small nonenveloped viruses, such as HAV and parvovirus B19 (B19), are evidently more difficult to remove than the larger enveloped viruses. However, since antibodies against these viruses, HAV and B19, are constantly present in large plasma pools, it is conceivable that antibody binding will lead to an increase in size of the viruses due to a corona of antibodies on the virus surfaces. These enlarged viruses should be easier to remove by nanofiltration than naked viruses. In this study, antibody-coated viruses and free virions were subjected to nanofiltration to determine whether the antibodymediated increase in size contributes to the elimination of viruses which are otherwise too small to be retained by filters of a given nominal pore diameter. STUDY DESIGN AND METHODS: One-percent IgG or 1-percent albumin solutions were spiked with bovine enterovirus (BEV) and filtered through 50-nm filters. This virus cross-reacts with antibodies in pooled human IgG solutions but persists as free virions in albumin solutions. Similarly, two parvoviruses, bovine parvovirus (BPV) and minute virus of mice (MVM), in 1-percent IgG solutions were filtered through 20-nm filters. BPV crossreacts with antibodies in human IgG, whereas MVM remains unaffected. Virus removal was assessed by in vitro infectivity assays. Two methods were developed to displace the antibodies from BEV and BPV and thereby render them accessible for titration. RESULTS: Antibody-coated BEV was eliminated to below detection limit by the 50-nm filters (logarithmic reduction factors [LRF] Ն 5), while free BEV virions passed without restraint through the same filters. Similarly, antibody-coated BPV was completely retained by the 20-nm filters (LRF Ն 5). MVM virions were strongly retained by the 20-nm filters; however, the virus was still detectable in the filtrate. CONCLUSION: These results indicate that viruses with bound antibodies are efficiently eliminated by nanofiltration by use of filters having nominal pore sizes larger than the diameter of the respective free virions. ABBREVIATIONS: B19 = parvovirus B19; BEV = bovine enterovirus; BPV = bovine parvovirus; BT = bovine turbinate; EMC = human encephalomyocarditis virus; GuHCl = guanidinium hydrochloride; LRF = logarithmic reduction factors; MVM = minute virus of mice; TCID 50 = tissue culture infectious dose 50 percent; TTV = TT virus.

Clinical Properties of a Novel Liquid Intravenous Immunoglobulin: Studies in Patients with Immune Thrombocytopenic Purpura and Primary Immunodeficiencies

“…This new 12% IgG solution differs from other IVIG products in various ways. Its virus safety is based on a series of pathogen inactivation and elimination steps, including nanofiltration, a technology that has the potential to enhance the prion-elimination capacity of the fractionation process as well [8][9][10]. Most importantly, however, the new formulation is stabilized by a novel approach being based on the excipients nicotinamide, L-proline, and L-isoleucine.…”

“…It has previously been shown that IgG preparations with a high dimer content were poorly tolerated [5][6][7]. Nanofiltration was introduced as an additional physical virus removal step, which also effectively contributes to the removal of the transmissible spongiform encephalopathy (TSE) agents in experimental models [8][9][10]. Furthermore, IVIG-F10 contains no sucrose or other carbohydrates and its immunoglobulin A (IgA) content is greatly reduced.…”

Immunoglobulin Replacement Therapy in Primary Antibody Deficiency Diseases – Maximizing Success

“…For instance, small-pore nanofilters that assure removal of most small pathogens are not always compatible with high-volume products such as IVIG. Large-pore and small-pore nanofilters to remove viruses from IVIG have been evaluated [54]. The results demonstrated that large viruses, such as enveloped viruses and some antibody-complexed small nonenveloped viruses were effectively removed by an IVIG-compatible large-pore nanofilter.…”

Non-enveloped virus reduction with quaternized chitosan nanofibers containing graphene

“…PPV and other mammalian parvoviruses have been extensively used as models for virus reduction techniques. [37][38][39][40] Parvoviruses are one of the smallest known viruses (18-26 nm in diameter) 41 and are difficult to inactivate by chemical or heat treatment. 27 They are most effectively removed by 20 nm pore-size nanofilters, but these filters are known to foul easily and have high pressure drops.…”