Inhibition of vaccinia virus growth by zinc ions: effects on early RNA and thymidine kinase synthesis.

Accumulation of thymidine kinase activity in vaccinia virus-infected cells was severely inhibited by zinc ions if the drug was added within 1 h postinfection. If added later, zinc ions had no effect on the enzyme synthesis. A fraction of RNA which is normally synthesized in infected cells, was missing from a proper part of the gradient if the cells were treated with zinc ions within 1 h postinfection (as has been shown by cosedimentation of pulse-labeled RNAs in isokinetic gradients). It is suggested that a transcriptional (or posttranscriptional) step is involved in zinc-caused inhibition of vaccinia virus growth.