Intracellular survival of B. abortus 2308(♦), Δomp10 (■) mutants in murine RAW264.7 cells. Macrophages were infected with the strains, and incubation at 37 oC for the indicated time. Bacteria intracellular growth in RAW264.7 cells was determined at different incubation time points by counting the viable intracellular bacteria. Each point represents the mean±standard deviation of three experiments. Statistically significant differences between the bacterial growth of the parent strain and the mutants are indicated by asterisks (***, P<0.001).