Construction of a site-specific, deletion-frameshift mutation in an essential gene of bacteriophage phiX174.

By in vitro methods, we have deleted 80 nucleotides from a preselected site in the coding sequence of gene G of bacteriophage phiX174. This mutant (Gdelta/FS ZH1) also carries a--2 frameshift. The mutation is lethal, but mutant virus can be stably maintained on host strains bearing plasmids carrying phiX gene G.