Fig. 3.

Infection of macrophages and mouse lungs by srnA mutants of L. pneumophila. (a) U937 cells were infected with wild-type strain 130b (■), srnA mutant NU328 (○), and srnA mutant NU329 (●). At various times post-inoculation, the numbers of bacteria per well were determined. The values presented are the means (±sd) obtained from four infected wells, and are representative of at least two independent experiments. (b) A/J mice were inoculated intratracheally with equal numbers of wild-type 130b and srnA mutant NU328, and then the ratio of wild-type to mutant was determined at days 1 and 3 after inoculation. Data are representative of actual values obtained per mouse (n=5), and the horizontal bar indicates the mean value.