FIG 1.

DotB is required for intracellular replication of L. longbeachae. (A) Replication of L. pneumophila 130b (filled triangles), L. pneumophila ΔdotA (open triangles), L. longbeachae NSW150 (filled circles) and L. longbeachae ΔdotB (open circles) in THP-1 macrophages. Following a 2-h infection and 1-h gentamicin treatment, the infection was allowed to proceed for 24, 48, or 72 h before cells were lysed and bacteria were enumerated. Results are the means ± standard deviations of the fold changes in CFU counts relative to the 3-h time point of at least three independent experiments. (B) Following gentamicin treatment, significantly more L. pneumophila bacteria (filled bars), as a percentage of the inoculum, were recovered than L. longbeachae bacteria (open bars). Without the gentamicin treatment, this difference was lost, and comparable proportions of the inoculum were recovered (P value calculated using an unpaired two-tailed t test; NS, not significant).