Concentration of retroviruses by low-speed centrifugation.

Concentration of retroviruses from volumes of up to 6 liters of medium by low-speed centrifugation is described. In contrast to pelleting, no damage or aggregation of particles was observed. Surface glycoproteins were also fully preserved. This method enables simple handling of relatively large volumes of medium. Highly purified mouse mammary tumor virus (MMTV) was obtained and its transframe protein p30 in SDS-PAGE was recognized as a double band.