Capturing of cell culture‐derived modified Vaccinia Ankara virus by ion exchange and pseudo‐affinity membrane adsorbers

Abstract

Smallpox is an acute, highly infectious viral disease unique to humans, and responsible for an estimated 300-500 million deaths in the 20th century. Following successful vaccination campaigns through the 19th and 20th centuries, smallpox was declared eradicated by the World Health Organization in 1980. However, the threat of using smallpox as a biological weapon prompted efforts of some governments to produce smallpox vaccines for emergency preparedness. An additional aspect for the interest in smallpox virus is its potential use as a platform technology for vector vaccines. In particular, the latter requires a high safety level for routine applications. IMVAMUNE, a third generation smallpox vaccine based on the attenuated Modified Vaccinia Ankara (MVA) virus, demonstrates superior safety compared to earlier generations and represents therefore an interesting choice as viral vector. Current downstream production processes of Vaccinia virus and MVA are mainly based on labor-intensive centrifugation and filtration methods, requiring expensive nuclease treatment in order to achieve sufficient low host-cell DNA levels for human vaccines. This study compares different ion exchange and pseudo-affinity membrane adsorbers (MA) to capture chicken embryo fibroblast cell-derived MVA-BN after cell homogenization and clarification. In parallel, the overall performance of classical bead-based resin chromatography (Cellufine sulfate and Toyopearl AF-Heparin) was investigated. The two tested pseudo-affinity MA (i.e., sulfated cellulose and heparin) were superior over the applied ion exchange MA in terms of virus yield and contaminant depletion. Furthermore, studies confirmed an expected increase in productivity resulting from the increased volume throughput of MA compared to classical bead-based column chromatography methods. Overall virus recovery was approximately 60% for both pseudo-affinity MA and the Cellufine sulfate resin. Depletion of total protein ranged between 86% and 102% for all tested matrices. Remaining dsDNA in the product fraction varied between 24% and 7% for the pseudo-affinity chromatography materials. Cellufine sulfate and the reinforced sulfated cellulose MA achieved the lowest dsDNA product contamination. Finally, by a combination of pseudo-affinity with anion exchange MA a further reduction of host-cell DNA was achieved.