Figure 1.

Intracellular growth of L. pneumophila in A549 cells. A549 cells were infected with L. pneumophila virulent AA100jm and avirulent dotO mutant strains at an MOI of 100. After 2 hours incubation, extracellular bacteria were removed by washing, and the infected cells were cultured further. The number of viable bacteria in each well was determined by the CFU counting method. Symbols : ▫, virulent strain AA100jm; ▪, avirulent strain dotO mutant. Data are mean ± SD of four wells. * P < 0.05.