Patent ID: 7465397

Claim:
A process for viral filtration of a protein containing stream comprising: (a) providing a filtration system comprising: (i) a pressurized reservoir comprising a solution which comprises one or more protein aggregates and viruses; (ii) a first conduit connecting the reservoir to a first filtration step comprising a device selected from the group consisting of one or more layers of adsorptive depth filters and one or more layers of charged or surface modified microporous membranes; (iii) a second conduit from the first filtration step to a second filtration step comprising one or more ultrafiltration membranes having a molecular weight cut off of between about 200 kD and about 1000 kD to retain virus particles in said one or more ultrafiltration membranes at a level of at least 3 LRV; and (d) an outlet conduit connected to the second filtration step; (b) pumping the solution from the pressurized reservoir through the first conduit to the first filtration step; (c) running the first filtration step in a normal flow filtration mode with the one or more protein aggregates and viruses being retained by the first filtration step; (d) discharging the solution from the first filtration step to the second conduit; (e) passing the solution from the second conduit through the second filtration step; and (f) discharging the solution from the second filtration step to the outlet conduit.