Background and objectives: Regulatory agencies have mandated that manufacturers of immunoglobulin products incorporate robust viral inactivation or removal steps into their purification processes. We evaluated the effectiveness of incorporating nanofiltration, a generic virus-clearance step, into an existing plasma-fractionation process for a human anti-D immunoglobulin product.
Materials and methods: The nanofiltration process studied utilizes a 180 000-molecular weight composite membrane with well-defined pore distribution. To examine its viral-clearance capability, diluted anti-D immunoglobulin was spiked with high concentrations of human and animal model viruses and subjected to tangential-flow nanofiltration during scaled-down validation runs. Viral clearance by the membrane was determined by calculating log removal values in accordance with guidelines provided by US and European regulatory agencies.
Results: Nanofiltration removed viruses of varying sizes and physical characteristics. For the three non-enveloped viruses tested (porcine parvovirus, encephalomyocarditis virus and hepatitis A virus, sizes 18-30 nm), clearance was 3.3, 4.1 and > 5.1 log, respectively. For the three enveloped viruses (human immunodeficiency virus-1, bovine viral diarrhoea virus and pseudorabies virus, 50-200 nm), a substantial 5-log reduction was demonstrated. Product potency, purity and stability were unaffected.
Conclusion: Tangential-flow nanofiltration provides substantial virus-removal capabilities for immunoglobulin preparations.