FIG. 4.

Immunoreactivity of serum antibodies with recombinant chlamydial surface proteins. Immunoglobulins (IgA and IgG) recognizing the indicated fusion proteins of C. pneumoniae and C. trachomatis were detected by Western blotting in a cohort of 41 human sera belonging to serogroups I to IV (panels A to D, respectively). The frequencies of positive reactions are presented for each serogroup and each individual chlamydial antigen. Secondary antibodies were directed against IgG (solid bars) and IgA (open bars).