Figure 5

Intracellular survival and replication of SPI-2 mutant Salmonella strains in U937 cells. The cultured HLA-B27 or HLA-A2-transfected U937 cells were infected with complement-opsonized S. Enteritidis PT4 KS8822/88 wild type or mutants and incubation of the bacteria-infected cells was continued at 37°C for 1, 4, 8 or 24 h after infection. At the defined time points, the host cells were lysed and the number of bacteria per cell was reported as colony forming units (CFU). The numbers of bacteria in each HLA-B27 cell (A) or HLA-A2 cell (B) at the indicated time points are shown. Values are mean ± standard deviation from three independent experiments with duplicate samples. * P < 0.05, statistically significant differences between the wild type and mutant strains. Data were compared using Student's paired 2-tailed t-test.