FIG 8 .

(A and B)  Role of ACP in meningococcal invasion of human cells. Chang, Hep2, HUVEC, and meningioma cell monolayers were challenged with MC58 ¢18 and MC58 ¢18 ΔACP strains (MOI, 100 to 200), and the numbers of both associated and internalized bacteria were quantified. Results of representative experiments for each cell line are shown, as reported by Virji et al. (15). Experiments were repeated 3 times, and the differences in association and/or invasion between the strains were reproducible between experiments, regardless of any quantitative variations between experiments. (C) Effect of rabbit anti-rACP serum on internalization of MC58 ¢18 strain into Chang epithelial cells and HUVECs. Cell monolayers (n = 3 experiments for each cell line) were infected for 4 h with strain MC58 ¢18 in the presence of 10% (vol/vol) preimmune and postimmune rabbit anti-rACP serum and the numbers of internalized bacteria quantified. For all figures, the columns represent the numbers of associated and/or internalized bacteria and the error bars the standard deviations of the results determined with triplicate wells. *, P < 0.05.