Virus filtration in continuous processing: Impact of low flux on virus retention and mitigation strategy

The current generation of parvovirus filters was designed to achieve maximum flux at high feed pressure to minimize batch processing time and filtration area requirements. These virus filters routinely achieve a greater than 5 log reduction value (LRV) within a 2-3 hour batch process. However, continuous processes require these same filters to process the same volumes over multiple days at operating pressures below 10 psi and flux of less than 100 LMH. New data will be presented on the potential reduction in LRV as the flux decreases below the typical batch filtration range. The industry needs to consider the impact of these new operating parameters when integrating virus filtration into continuous processes. A method is introduced here for efficient utilization of virus filters within a continuous process, in which the virus filter is operated intermittently at high flux (thereby ensuring maximum virus retention performance) while also allowing for extended filter changeout time. Experimental data on filter throughput and virus retention performance, covering a multiple day virus filtration run using an intermittent high flux approach, will be presented.