Viruses and virus assays
MMV (ATCC VR-1346, strain Prototype; Family Parvoviridae ; non-enveloped ssDNA virus; Ø = 18 - 26 nm) was propagated and titrated on A9 cells (ATCC CCL-1.4), as previously reported Berting, (2010).
Titers from the end-point dilution assays were expressed as log10 50% tissue culture infectious dose/mL (TCID50/mL) and any influences of the process material upon the virus infectivity assay characteristics, cell toxicity and interference were considered.
Analysis of the virus removal capacity of the process was carried out as described in or according to regulatory guidance (EMEA, (1996)). The virus load before and after treatment were used to calculate the logarithmic virus reduction factor (R). It is noted that the “after treatment” virus load is the sum of the virus loads of each filtrate fraction drawn during an experiment. Whenever virus was undetectable, the limit of detection was taken as the virus titer for calculation.