Fig. 2.

Pneumococcal colonization elicits serum antibody that cross-reacts with S. aureus. Sera were collected from C57BL/6 mice before (pre) and after (post) intranasal colonization with S. pneumoniae TIGR4. (A) Representative histogram of flow cytometric detection of antibody binding to S. aureus 8325–4spa incubated with mouse sera taken before (light gray line) and after (dark gray line) pneumococcal colonization. Control (no primary antibody) is shaded gray. (B) Western blot of S. aureus 8325–4spa lysates incubated with mouse sera taken before (PRE) and after (POST) pneumococcal (Sp) or sham (PBS) colonization. Data are representative of >10 biological replicates. Arrow indicates candidate target of cross-reactive antibody.