Concentration of human cytomegalovirus from large volumes of tissue culture fluids.

Three methods of pelleting, ultracentrifugation (95000 g for 60 min), precipitation with polyethylene glycol 6000 (5% v/v), and with ammonium sulphate (38% w/v), were used to concentrate human cytomegalovirus (CMV) from tissue culture fluids. Maximum recovery of infectious virus particles was obtained with the polyethylene glycol (PEG) method. The precipitating activity of PEG 6000 and PEG 20000 was then compared at different concentrations. The best results were obtained with PEG 6000 at a final concentration of 5% (v/v). Changes in pH or salt concentration, treatment of the concentrates with Pronase and long periods of time at 4 degrees C significantly reduced the number of biologically active CMV particles recovered by PEG precipitation.