Purification of avian encephalomyelitis virus by ultracentrifugation in a nonlinear cesium chloride gradient

A rapid and convenient method is described for purifying avian encephalomyelitis virus. Infected embryo homogenate was treated with polyethylene glycol followed by extraction with fluorocarbon. Extracted sample was pelleted at 73,400 x g, resuspended, and subjected to isodensity centrifugation in preformed nonlinear gradient. A distinctive virus band was observed after centrifugation for 120 min at 192,000 x g. The fraction containing the virus band demonstrated the major portion of infectivity and the presence of the virus particles by electron microscopy. The method was reproducible within a limited number of trials.