Affinity chromatography to remove viruses during preparation of plasma derivatives.

The use of affinity chromatography methods to purify proteins from complex solutions is well established. The specific use of immuno-affinity chromatography, wherein antibody directed toward a target protein is utilized, has proven to be a particularly effective purification method. Application of immuno-affinity chromatography methods for the isolation of plasma derivatives has now been established and the purity of such products has been truly remarkable. Studies conducted by Baxter have compared the effect of immuno-affinity chromatography on the separation of plasma protein contaminants and model viruses from Factor VIII:C. The results of these studies have indicated that plasma protein contaminant (eg. fibrinogen) reduction during the process of Factor VIII:C immuno-affinity chromatography occurs more gradually than does virus reduction. By using residual plasma protein contamination in Factor VIII:C preparations, the general effectiveness of the immuno-affinity chromatography step in removing virus can be routinely evaluated. Determinations made by Baxter have indicated that greater than 4 logs of reduction in protein contamination is routinely achieved during Factor VIII:C immuno-affinity chromatography at manufacturing scale. Bench scale studies have confirmed this result as well as showing the reduction of model viruses. While the viral safety of plasma derivatives is dependent on the overall manufacturing process, it is clear that immuno-affinity chromatography offers a powerful means of reducing product contamination and enhancing safety.