FIG. 2.

(A) Expression of β-galactosidase is dependent on the M2-1 protein. The indicated amount of pM2-1 expression plasmid was transfected into MVA-T7-infected HEp-2 cells together with 0.2 μg of pN, 0.2 μg of pP, 0.2 μg of pL, and 0.2 μg of pRSVLacZ minigenome. Thirty-six hours after transfection, the β-galactosidase activity was measured by incubating the cell lysates with 5 mM CPRG for 5 min. An average of three transfection experiments is shown. (B) Comparison of β-galactosidase activity from cells transfected with wt and mutant M2-1 expression plasmids. Cells were transfected with 0.3 μg of wt M2-1 plasmid, and the β-galactosidase activity following 30 min of incubation with CPRG is shown. (C) β-Galactosidase activities from cells transfected with wt, C96G, or Tr17 M2-1. The enzymatic activity was monitored for 45 min after incubation of the cell lysates with CPRG. The signal was linearly responsive up to an OD₅₅₀ of 3.0. (D) Northern blot of total RNA extracted from HEp-2 cells transfected with wt and mutant M2-1 expression plasmids. The blot was hybridized with a riboprobe specific for β-galactosidase mRNA. The LacZ antigenome is also indicated.