FIG 7 .

Intracellular infection of A. castellanii by the L. pneumophila wild-type strain, lapA plaC mutant, and lspF mutant in the presence of added amino acids. A. castellanii amoebas were infected with wild-type strain 130b (WT), lapA plaC mutant NU435, or lspF mutant NU275, and, at the indicated times, bacterial growth was determined. Where indicated, the medium in the infected wells was supplemented with 1 mM excess amino acids (AA) for the duration of the experiment. Growth data are presented as means with standard errors of results from three independent experiments (n = 3 each). Asterisks indicate significant differences in CFU recovery between strains under the given conditions (*, P < 0.05; **, P < 0.01 [Student’s t test]). ns, not significant.