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.