TABLE 3.

Effect of VirR box mutations on perfringolysin O activity

PlasmidaCharacteristicsPFO titer (log2)b
pJIR751Shuttle vector, negative control<1.0
pJIR1972pfoR+ pfoA+, positive control5.6 ± 0.7
pJIR2266Cloning vector<1.0
pJIR2279Wild-type VirR boxes5.7 ± 0.2
pJIR2280Mutation in VirR box 12.3 ± 0.1
pJIR2277Mutation in VirR box 22.1 ± 0.3
pJIR2278Mutation in both VirR boxes2.1 ± 0.3
  • a All plasmids were analyzed in strain JIR4228.

  • b PFO titer refers to the mean perfringolysin O titer (± standard deviation) obtained from duplicate assays using supernatants from three independent cultures of each strain. Note that these titers are reported on a logarithmic, not arithmetic, scale.