Infection of J774 macrophages with wild type 4/74 and Δ<i>pspE</i>, Δ<i>glpE</i> and Δ<i>pspE/glpE</i> strains.

<p>J774A.1 macrophages were infected with complemented-opsonized bacteria in a MOI of 10 and incubated for 25 min. Extracellular bacteria were killed by treatment with 100 µg ml⁻¹ gentamicin. Bacteria were released from the macrophages 1 h p.i., 4 h p.i. and 24 h p.i. and the number of intracellular bacteria was determined by CFU ml⁻¹ calculations and was expressed relatively to CFU at T1. The results show mean values ± SEM of at least three independent replicates. The small inserts shows results of an internal control experiment conducted with a SPI-2 (<i>ΔssaV</i>) deficient strain showing the expected reduced intracellular survival/replication of the mutated strain.