Host cells accelerate microcolony dispersal independent of direct contact.

<p>Microcolony formation and dispersal of <i>N</i>. <i>meningitidis</i> FAM20 (2 × 10⁶ CFU/ml) were monitored for 8 h by live-cell time-lapse microscopy after infection of FaDu cells. (A) FaDu cells at confluences of 100%, 80%, 50%, 20% and 0% were infected with FAM20. (B) The dispersal of FAM20 microcolonies on FaDu cells at 50% confluence was observed with live-cell time-lapse microscopy. Representative images are shown. Scale bar, 10 μm. (C) FaDu cells were infected with FAM20 or the Δ<i>pilC1</i> mutant. (D) FAM20 infecting fixed (3.7% paraformaldehyde) or live FaDu cells. Data represent the mean ± SD for at least three individual experiments. ^*p < 0.05. ns, non-significant.