Established robustness of viral filtration and existing knowledge gaps
As previously stated, the broadly accepted mechanism of virus removal by viral filtration is size based sieving which is relatively unaffected by physiochemical characteristics of the viral species. Decades of scale-down scientific studies with viral filters support the robust and effective removal of viruses under varying typical and worst-case process conditions. Parameters typically evaluated in viral filter studies include feed pressure, differential pressure, product loading, flow pausing, or solution conditions (e.g. pH, ionic strength, protein concentration, etc.). Existing published filtration studies are summarized in brief in sections below.