A virulence-associated filamentous bacteriophage of Neisseria meningitidis increases host-cell colonisation
(A) Quantification of the biomass covering cells infected with pilE mutants (Z5463gfpΔpilE and Z5463gfpΔpilEΔMDA). Mutants were grown onto FaDu epithelial cells for 18 hours under constant flow. At least three independent experiments were performed. The results are normalized as a percentage of the mean biomass of Z5463gfpΔpilE, which was set to 100%. Error bars indicate the standard errors of the mean (SEM). *p < 0.05 (Student t test). (B) Three-dimensional biomass of colonizing bacteria reconstructed with the Imaris software. (1) non piliated strain. (2) a prophage deleted isogenic mutant of the non piliated strain. Both strains were grown onto FaDu epithelial cells for 18 hours under constant flow shear stress. Representative images of experiments performed on at least three different occasions. Bacteria are stained with GFP (in green) and epithelial cells are stained with cytoplasmic Cell Tracker Orange CMTMR (in red). (C) Immunogold-labelling of Z5463gfpΔpilE strain. Material was harvested from a flow chamber as above and labelled with the anti-MDAORF4 polyclonal antibody. In this experiment, only 18 nm-diameter gold particles were used. Global view with some enlargements. The letter B in white corresponds to bacteria.