Ranil Wickramasinghe

Biotechnological manufacturing processes make use of animal cells, often mammalian cells to produce the therapeutic of interest. While traditionally these were protein based therapeutics, today there are many new emerging therapeutics such as live attenuated virus vaccines, viral vectors for delivery of gene therapy products, virus like particles, plasmid DNA, glycoconjugate vaccines, cell-based therapies etc.. These emerging therapeutics add additional complexity to the downstream purification operations.

Membrane based separations are attractive for a number of reasons such as easy scale up, lower operating cost and the potential for significant process intensification. For applications in bioseparations linear scale up is important given the regulatory approvals needed for a manufacturing process. Membrane based processes such as membrane adsorbers, ultrafiltration and virus filtration are routinely used in the purification of these products. This presentation will discuss some of the important membrane based unit operation and the need to improve their performance.

Validation of virus clearance is a major challenge in the manufacture of biopharmaceuticals. Contaminating virus particle e.g., in the manufacture of monoclonal antibodies (mAbs), must be removed prior to regulatory approval. Virus filtration, (sometimes referred to as nanofiltration in the biopharmaceutical industry) removes viruses from the process stream by size exclusion. It is a dedicated step in most downstream bioprocesses. The industrial expectation for a robust small parvovirus filter is at least four log (10⁴) reduction of virus particles. An ideal virus filtration membrane would retain all the virus particles with no rejection of the product. Since small viruses, such as parvovirus, are 18–26 nm in size while mAbs can be up to 12 nm in size, rejection of virus and recovery of the product protein in the filtrate can be particularly challenging. As virus filtration always occurs towards the end of the purification process, fouling of the virus filter is by product related foulants such as product dimers, trimers etc. Here we show the importance of virus prefiltration in order to improve the performance of the virus filter. Further batch processing is used in the manufacture of biopharmaceutical products. However, there is a growing interest in continuous biomanufacturing processes which further complicates virus filtration. Adapting virus filtration to continuous biomanufacturing operations as well as a model to describe the performance of a virus filters will be described.

Today, recovery and purification of virus particle is of growing interest. These virus particle represent the therapeutic of interest. However purification of virus particles is particularly challenging when using unit operations that were optimized for protein purification. Two specific challenge will be addressed here. The first is virus harvesting which involves recovering virus particles from the bioreactor while removing cells and cell debris. A tangential flow filtration process will be described.

Cell culture-based processes often produce a large number of defective or empty virus capsids which should be removed from the product (filled capsids). This represents the second major challenge in the purification of virus particles. Often recoveries are around 50%. Here results will be presented on the use of multimodal membrane adsorbers for purification of filled Adeno Associated Virus (AAV) capsids.

Ranil Wickramasinghe is a distinguished professor in the Department of Chemical Engineering at the University of Arkansas where he holds the Ross E Martin Chair in Emerging Technologies. He is an Arkansas Research Alliance Scholar. He is the Director of the Membrane Applications Science and Technology (MAST) Center, a NSF Industry and University Cooperative Research Center. Prof Wickramasinghe is the Executive Editor of Separation Science and Technology. He is a Fellow of the American Institute of Chemical Engineers and currently serves on the Board of Directors of the North American Membrane Society. He is the winner of the 2023 American Institute of Chemical Engineers Separations Division Gerhold Award. He has published over 200 peer reviewed journal articles several book chapters and is co-editor of books on responsive membranes and materials and hollow fiber contactors.

Prof Wickramasinghe obtained his bachelor’s and master’s degrees from the University of Melbourne in Chemical Engineering. He obtained his PhD from the University of Minnesota, also in Chemical Engineering. Prof Wickramasinghe’s research interests are in membrane science and technology. His research focuses on synthetic membrane-based separation processes for purification of pharmaceuticals and biopharmaceuticals, treatment and reuse of water and for the production of biofuels. Typical unit operations include: microfiltration, ultrafiltration, virus filtration, nanofiltration, membrane extraction, membrane distillation etc. A current research focus is surface modification of membranes in order to impart unique surface properties. His group is actively developing responsive membranes. These membranes change their physical properties in response to changed environmental conditions. A second research focus is the development of catalytic membranes for biomass hydrolysis by grafting catalytic groups to the membrane surface.

• Time: 11:00 AM
• Location: 206 Furnas Hall