Antibody response to B cell epitopes of Chlamydia trachomatis 60-kDa heat-shock protein and corresponding mycobacterial and human peptides in infants with chlamydial pneumonitis.

To study antibody response to the hypersensitivity protein B of Chlamydia trachomatis, also known as the 60-kDa heat-shock protein (hsp60), epitope scanning was done over the entire protein. Human sera with antibodies to C. trachomatis identified 5 major antigenic regions (peptides 2, 5, 9, 17, and 21) and several minor regions (peptides 34-37, 39, 50, and 59-62). Clear-cut IgG antibody responses to chlamydial peptide 2 (YNEEARKKIQKGVKT) and a corresponding mycobacterial peptide (YDEEARRGLERGLNA) were found in 8 of 16 infants with chlamydial pneumonitis and in 1 of 18 controls. Peptide 50 (RLAKLSGGVAVIRVG) showed an 80% identity with its human counterpart (RLAKLSDGVAVLKVG), which was derived from human mitochondrial protein P1, but specific antipeptide antibody responses were found in 3 of 16 cases only. In summary, both IgG antibody response to C. trachomatis hsp60 and occasional autoantibody formation in infants with chlamydial pneumonitis were found.