Fluorescence screen of Himar 1 mutant replication in macrophage. Preliminary screening was performed using J774.A1 macrophage-like cells that were infected with B. melitensis 16 M (panel A) or individual mutants (panels B, C, D) in 96-well microtiter dishes at MOI of 50, as described in Materials and Methods. Replication of each mutant was visualized using goat anti-B. melitensis and donkey-anti-goat IgG-Alexa Fluor 488. Images similar to those shown were captured using an Olympus IX70 inverted fluorescent microscope.