Site of the base change in the vaccinia virus DNA polymerase gene which confers aphidicolin resistance.

An aphidicolin-resistant mutant of vaccinia virus has been shown to encode an altered viral DNA polymerase that is more resistant to aphidicolin. Marker transfer experiments with the DNA from the resistant virus localized the mutation site to an RsaI segment within the portion of the HindIII-E segment which has been shown to contain the viral DNA polymerase gene. Nucleotide sequence analysis of the mutant DNA showed a single GC to AT transition at position 2430, which indicates a leucine-to-methionine change at residue 645 in the protein.