FIG. 4.

(A) Genomic structure of the recombinant ASFV virus vE120Ri. Recombinant virus vE120Ri was obtained from recombinant vGUSREP, which contains the lacI gene encoding the lac repressor inserted into the nonessential tk locus. In vE120Ri virus, the gene E120R is under the transcriptional control of an inducible promoter p72.1, which is composed by the strong late promoter p72.4 and the lac operator sequence (●). The reporter genes lacZ and gusA, used for selection and purification of the recombinants, are also represented. (B) Plaque phenotype of vE120Ri. Monolayers of Vero cells were infected in the absence or presence of 1 mM IPTG with parental BA71V or recombinant vE120Ri virus. Plaques were visualized with 1% crystal violet 5 days after infection. (C) Inducible expression of protein pE120R. Vero cells were infected with BA71V or recombinant vE120Ri in the presence (+) or absence (−) of 1 mM IPTG. At 24 hpi, samples were electrophoresed and analyzed by Western immunoblotting with a serum anti-pE120R. The electrophoretic mobility of molecular weight markers is indicated on the left.