title: The concentration of Polyoma virus by ammonium sulfate precipitation and purification by density gradient centrifugation.
mesh_terms: D002499:Centrifugation, Density Gradient; D011120:Polyomavirus / Q000302:isolation & purification*; D000644:Quaternary Ammonium Compounds; D013431:Sulfates
chemical_list: D000644:Quaternary Ammonium Compounds; D013431:Sulfates