FIG. 5.

Ratio of concentrations of L. pneumophila strains F2310 (lvgA⁺) and F2341 (lvgA mutant) in explanted guinea pig alveolar macrophages. Equal concentrations of F2310 and F2341 were added to the same tissue culture wells, and the ratio of F2310 to F2341 was determined by observing the differential growth on media with and without kanamycin. The inset shows the total (F2341 plus F2310) bacterial concentrations. Cells were infected on day 0. Means and standard errors of the means for triplicate wells are shown. Note the two different axis scales. The data are representative of two independent experiments.