TABLE 4.

Effect of altering DNA spacing and other VirR boxes on perfringolysin O activity

PlasmidaCharacteristicsPFO titer (log2)b
pJIR751Shuttle vector, negative control<1.0
pJIR1972pfoR+ pfoA+, positive control5.9 ± 0.5
pJIR2373Cloning vector1.4 ± 0.1
pJIR2422Wild-type VirR boxes upstream of pfoA5.8 ± 0.5
pJIR2447Insertion of 5 bp between VirR boxes1.3 ± 0.03
pJIR2448Insertion of 10 bp between VirR boxes2.5 ± 0.1
pJIR2481Deletion of 5 bp between VirR boxes1.4 ± 0.1
pJIR2632Insertion of 5 bp between VirR box 2 and −35 box1.1 ± 0.4
pJIR2620Insertion of 10 bp between VirR box 2 and −35 box1.3 ± 0.4
pJIR2479VirR boxes from upstream of CPE08453.7 ± 0.3
pJIR2483VirR boxes from upstream of CPE08467.6 ± 0.3
pJIR2480VirR boxes from upstream of CPE09204.4 ± 0.1
pJIR2489VirR boxes from upstream of hyp76.7 ± 0.2
  • 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.