Incorporation of an additional viral-clearance step into a human immunoglobulin manufacturing process

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.

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.

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.

Tangential-flow nanofiltration provides substantial virus-removal capabilities for immunoglobulin preparations.