Nanofiltration, a new specific virus elimination method applied to high-purity factor IX and factor XI concentrates.

We have validated the use of two new regenerated multilayered structured cellulose membranes (BMM), Planova 15 N and Planova 35 N, with respective mean pore sizes of 15 and 35 nm, as a new filtration system to eliminate viruses in highly purified factor IX and factor XI concentrates. Virus spiking experiments indicated that single dead-end filtration on the membranes could remove more than 5.7-7.8 log10 of human immunodeficiency virus, bovine viral diarrhoea virus, porcine pseudorabies virus, reovirus type 3, and simian virus 40, as well as the small non-enveloped viruses, poliovirus Sabin type 1 and bovine parvovirus. In vitro control tests and animal studies (Wessler stasis model, rat hypotension model) of the two concentrates did not reveal any significant differences with the non-nanofiltered material. Viral filtration of plasma derivatives on porous polymeric membranes might be an essential step in the improvement of their viral safety.