Procedure for purification of intact DNA from vaccinia virus

A procedure for the isolation of intact vaccinia DNA molecules by chromatography on hydroxyapatite in the presence of 6 M urea is described. When lysates of virions containing 0.5 to 10 microgram of DNA were employed, over 95% of the viral DNA could be recovered free of poteins. Vaccinia DNA molecules isolated in this manner sedimented at 68S in neutral sucrose gradients and had an average contour length of 62.3 micrometer when examined in an electron microscope, and the DNA could be cleaved with the restriction endonuclease EcoRI and BamHI. The results of these analyses showed that intact vaccinia DNA molecules of 120 X 10(6) to 130 X 10(6) molecular weight could be obtained by the procedures described.