FIG 1 .

Relative expression levels of genes encoding type II-secreted proteins (effectors) in wild-type L. pneumophila grown in broth or within amoebas and human macrophages. (A) Gene expression within wild-type 130b bacteria grown in BYE broth to the exponential phase (E phase) or stationary phase. qRT-PCR data are presented as means with standard errors of results from three independently grown cultures, with expression in the stationary phase normalized to expression in the E phase in broth. (B to D) Gene expression within 130b bacteria obtained from infected A. castellanii (B) or N. lovaniensis (C) at 44 h postinoculation or from infected human U937 macrophages (D) at 12 h postinoculation. qRT-PCR data are presented as means with standard errors of results from three independent infections (n = 3 each), with the intracellular expression normalized to the E phase in broth. Dashed lines indicate the customary 1.5-fold up- and/or downregulation threshold of biological interest. Asterisks indicate significant differences with >1.5-fold change relative to the E phase (*, P < 0.05; **, P < 0.01; ***, P < 0.001 [one-sample t test]).