Disclosed are isolated Chlamydia trachomatis proteins, methods of fusion protein and associated antibody production, and methods of using isolated proteins and antibodies in diagnosis and detection. Also disclosed are compositions comprising isolated proteins, wherein the compositions can further comprising pharmaceutically acceptable carriers, an adjuvant and/or an immunostimulant, and methods using the pharmaceutical compositions for treating or preventing an infection by Chlamydia in a subject. The compositions may also comprise a protein or immunogenic fragment of a pathogenic organism other than Chlamydia trachomatis.