Comparison of different methods for large-volume concentration of a type D retrovirus (PMFV)

Different methods of large-scale concentration of a type D retrovirus (PMFV) were compared, including continuous-flow centrifugation, ultrafiltration, and polyethylene glycol precipitation. Best results were obtained by a combination of continuous-flow centrifugation and subsequent purification by velocity gradient and isopycnic gradient centrifugation.