摘要 |
A process is provided for selectively removing protein aggregates and virus particles from a protein solution in a two-step filtration process. In a first step, a protein solution is filtered by tangential flow filtration through a cellulosic ultrafiltrate membrane at a transmembrane pressure of between about 1 and about 10 psi to produce a first permeate and a retentate stream. Water or aqueous buffer is added to the retentate stream to form an essentially constant volume retentate stream. The first permeate is filtered through a second ultrafiltration membrane to retain virus particles at a retention level of at least 3 LRV and to allow passage therethrough of a protein aggregate free and virus free protein solution. |