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.