Figure 1. Overview of the development of the logarithmic reduction factor (R) during representative runs for each filter investigated. Arrows pointing up indicate the corresponding filtrate fraction titer was below the limit of detection.
The virus reduction factor values (R) in relation to filtered volumes are summarized in Figure 1. Filters FG I to FG III exhibited significant MMV breakthrough resulting in a rapidly decreasing R values – even though initial values (when volumes were near to the volumes the filters were designed for) were not unpromising. Filter FG IV shows effective virus clearance, however, with some significant virus breakthrough after a loading of more than 2000 L/m² or due to process interruptions. All other filters show effective virus clearance, whereby filters SG I and SG II show the best virus clearance capacities at the highest process feed loads and were thus best suited for the intended purpose.