FIG 9.

Complementation of phenotypes associated with L. pneumophila OTU mutants with counterparts from L. longbeachae. (A and B) Plasmids coding for the relevant L. longbeachae OTU genes and their derivatives were transformed into L. pneumophila Δlem27 or Δceg23. U937 cells were challenged with indicated L. pneumophila strains for 2 h at an MOI of 10. Cells were then fixed and sequentially immunostained with L. pneumophila and K63-linkage specific (A) or FK1 (B) polyubiquitin antibodies. Staining signals were visualized by a fluorescence microscope. The percentage of phagosomes decorated with polyubiquitinated proteins. Results are mean ± SD counted from three coverslips. Similar results are observed in three independent experiments. Statistics analysis was performed by unpaired two-tailed Student t tests, and a P value of <0.05 indicates a significant difference.