A VACCINIA VIRUS ISATIN-BETA-THIOSEMICARBAZONE RESISTANCE MUTATION MAPS IN THE VIRAL GENE ENCODING THE 132-KDA SUBUNIT OF RNA-POLYMERASE

The mutation in a vaccinia virus mutant resistant to inhibition by isatin-β-thiosemicarbazone was mapped by marker rescue. DNA from the resistant mutant was cloned into cosmid and plasmid vectors and tested for its ability to convert wild-type vaccinia virus to IBT resistant virus in a helper-mediated marker rescue protocol. Resistance was mapped in this way to a 0.9-kb DNA fragment derived from the HindIII A fragment of vaccinia genome. Southern blot hybridization using this DNA as a probe demonstrated that the 0.9-kb fragment is contained within the DNA sequence encoding the second largest subunit of vaccinia RNA polymerase, rpol32. Thus, mutation of rpo132 can cause resistance to IBT in vaccinia virus. © 1991.