Anion-exchange (AEX) chromatography is a well-established polishing step for removal of viruses and other impurities during downstream processing of biotherapeutics. Before initiating phase 1 clinical trials, a representative scaled-down model of the final process must be available for use in viral-clearance studies. At that point, however, scientists usually have no way of knowing how effective a process will be for removing viruses. In this article, scientists from Thermo Fisher Scientific and Bristol Myers Squibb (BMS) describe their efforts to define…