IglA expression in J774 macrophages. Western blot showing expression of IglA during infection of macrophages. J774 macrophages were infected with parent strain U112 (m.o.i 300:1) and lysed at the indicated time post infection. Loading was normalized according to the number of viable bacteria (CFU) in each sample as determined by plating on TSA-C plates. Lane J774, uninfected macrophages. TSB, broth grown U112 grown to indicated optical density (600 nm). All samples were normalized to 107 CFU by viable counts. The macrophage cell lysates altered the appearance of the IglA bands, but control experiments showed that the cell lysates did not mask IglA reactivity with antibody.