Performance of a Novel Viresolve NFR Virus Filter

Abstract

Mammalian cell-expressed therapeutic proteins are particularly vulnerable to contamination by endogenous retrovirus-like particles (RVLPs). The Viresolve NFR filter was designed to meet the critical requirement of manufacturing a safe and virus-free therapeutic by retaining RVLPs by a minimum of six log reduction value (LRV). The NFR designation refers to retrovirus removal in a normal flow format. To qualify the product, we tested two model viruses: the 78 nm diameter phi6 bacteriophage and the 80-110 nm diameter Xenotropic Murine Leukemia Virus (X-MuLV). Robust retention was demonstrated over a wide range of process parameters. Viresolve NFR filters also retain other model adventitious viruses including 70-85 nm diameter Reovirus 3 (Reo3), 70-90 nm diameter Adenovirus 2 (Ad2), and 53 nm diameter PR772 by >6 LRV. In addition to these model viruses, the filter retains >7 LRV of both the mycoplasma Acholeplasma laidlawii and the bacterium Brevundimonas diminuta. Protein passage is shown to be consistently high (95-100%) for a variety of therapeutic protein products, including monoclonal antibodies. Characterization of the filter in specific applications is made simple by availability of ultralow surface area (5 cm(2)) disks, which are shown to scale linearly to the manufacturing scale pleated-filters. Viresolve NFR filters provide consistent water permeability performance (34-37 LMH/psi) and show very little plugging for all feedstocks evaluated. The Viresolve NFR filter incorporates Retropore, a unique asymmetric polyethersulfone membrane, the surface of which has been modified to minimize protein binding.

Characterization of Coliphage PR772 and Evaluation of Its Use for Virus Filter Performance Testing

“…Recently, a consensus has emerged among filter manufacturers and end users in the biopharmaceutical industry about the desirability of a common nomenclature system to facilitate performance comparisons between virus removal filters from different manufacturers. Bacteriophages have been used for decades in medical size-based removal applications (3); more recently, filter manufacturers have used phages to evaluate the size exclusion properties of their viral removal filters (3,4,12,19,(25)(26)(27). On the basis of its reported 53-to 63-nm diameter (6,15,16) and its previous successful use in testing size exclusion properties of large-virus filters (4,12,(24)(25)(26), PR772 has been suggested by the Parenteral Drug Association virus filter task force to be a potential model bacteriophage to standardize nomenclature for large-pore-size virus filters (G. Sofer, unpublished data).…”

“…Because of its reported diameter (53 to 63 nm) (6,15,16) and its previous successful use in testing size exclusion properties of large-virus filters (4,12,(24)(25)(26), PR772 has been chosen by the Parenteral Drug Association virus filter task force to be the model bacteriophage to standardize nomenclature for larger-pore-size virus filters (G. Sofer, unpublished data). PR772 belongs to the Tectiviridae family of icosahedral double-stranded DNA bacteriophages (6,7,15,16).…”

“…Phage PR772 has proven useful in the past to evaluate the size exclusion properties of large-pore-size virus filters under various operating conditions (4,12,(24)(25)(26). Further, routine filter testing with PR772 is preferable because of its nonpathogenic host compared to the usual host of PRD1 (Salmonella enterica serovar Typhimurium), which is a pathogen (risk group 2 organism) that must be handled in a level 2 containment laboratory.…”

Effect of solution pH on protein transmission and membrane capacity during virus filtration

“…When originally developed, virus filtration was performed using tangential flow filtration with the membrane oriented so that the virusretentive skin layer faced the feed. Current applications of virus filtration use disposable normal flow filters, with the more open side of the membrane facing the feed stream (Brough et al, 2002). This orientation provides greater capacity than obtained with the skin-side up, which is usually attributed to the capture of protein aggregates and other large foulants within the macroporous substructure thereby protecting the virus-retentive skin layer (Syedain et al, 2006).…”

Application of high‐performance tangential flow filtration (HPTFF) to the purification of a human pharmaceutical antibody fragment expressed in Escherichia coli

“…This has been demonstrated in microfiltration using Dean vortices (Belfort, 1997;Gehlert et al, 1998), in normal flow clarification (Charlton et al, 1999) and in ultrafiltration using charged membranes . A second strategy is to offer alternatives to chromatography such as normal flow adsorption membranes (Roper and Lightfoot, 1995;Santarelli et al, 1998) and virus filtration (Aranha-Creado et al, 1998;Brough et al, 2002). A third development strategy is to reduce the number of purification process steps to decrease the cost of goods (COG).…”