Replication of poxvirus DNA in chick embryo fibroblasts

Replication of vaccinia virus DNA in chick embryo fibroblasts at a high multiplicity of infection started after 4-6 hr, reached a maximum at the 12th hr and was completed 18 hr after inoculation (p.i.). An analysis of newly synthesised DNAs in the period of the highest rate of synthesis revealed the formation of short (10-30S) fragments which within 30 min were transformed into single-stranded molecules with a sedimentation coefficient of 62S. The final stage of closing of the ends of single-stranded molecules needed much more time and the bulk of "mature" single-stranded 90 S DNA molecules was observed 17 hr p.i.