FIG. 5.

Construction of a conditional lethal inducible G7L VV. (A) Schematic diagram representing the genome of vG7Li. The J2R (thymidine kinase [TK]), G7L, and A56R (HA) loci are shown. Insertions into these loci are displayed below the line. Additional abbreviations: P11, a VV late promoter, P7.5, a VV early late promoter; lacO, E. coli lac operator; lacI, E. coli lac repressor gene; T7 pol, bacteriophage T7 RNA polymerase gene; PT7, bacteriophage T7 promoter; EMC, encephalomyocarditis virus mRNA cap-independent translation enhancer element; gus, E. coli β-glucuronidase gene; gpt, E. coli guanine phosphoribosyltransferase gene. (B) Effect of IPTG on virus plaque formation. BS-C-1 cell monolayers were infected with vT7lacOI, vG7L/G7Li, or vG7Li in the presence (+) or absence (−) of 50 μM IPTG in the methylcellulose overlay. Cells were stained with crystal violet 48 h after infection.