Table 2.

Quantitation of GFP expression versus F-actin staining ofL. monocytogenes actA-gfp-plcB mutants following infection of PtK2 cells

Expt no. and time (h) post-infectionNo. of GFP-positive bacteriaaNo. of GFP- and F-actin- positive bacteriab% GFP+ and:
F-actinF-actin+
1
 1.5262928
 2.03487624
 2.561501882
 4.06563397
2
 1.51538020
 2.050176634
 2.559422971
 4.060531288
3
 1.563177327
 2.062275644
 2.557383466
 4.05551793
Mean ± SDc
 1.582 ± 718 ± 7
 2.066 ± 734 ± 7
 2.527 ± 673 ± 6
 4.0 7 ± 393 ± 3
  • a Number of intracellular L. monocytogenes bacteria that scored positive for GFP expression following examination of infected cells by fluorescence microscopy. Numbers are taken from at least 20 different microscopic fields equivalent in size.

  • b Number of intracellular L. monocytogenes bacteria that scored positive for GFP expression and F-actin accumulation following examination of cells by fluorescence microscopy. Numbers are taken from at least 20 different microscopic fields equivalent in size.

  • c Mean values derived from three individual experiments are shown. Similar results were obtained from two additional independent experiments (data not shown).