FIG. 5.

Intracellular infection of A. castellanii by the wild type, an lspF mutant, and a proA mutant of L. pneumophila. Acanthamoebae, cultured in standard proteose peptone-yeast extract-glucose medium (A) or 1034 medium (B), were infected with wild-type 130b (⧫), lspF mutant NU275 (•), and proA mutant AA200 (○) and then, at various times postinoculation, the numbers of bacteria per well were determined. The values presented are the means and standard deviations obtained from three infected wells and are representative of at least two independent experiments. At 48 to 96 h postinoculation, and under both growth conditions, the recovery of the lspF mutant was significantly less than that of the wild type and the other mutant (P < 0.05; Student's t test). In contrast, the slightly reduced recoveries of the proA mutant relative to the wild type seen at some points were not significant.