The present invention provides purified and isolated polynucleotide molecules that encode Chlamydia polypeptides which can be used in methods to prevent, treat, and diagnose Chlamydia infection. In one form of the invention, the polynucleotide molecules are selected from DNA that encode polypeptides CPN100686 RY 54 (SEQ ID Nos: 1 and 14), CPN100696 RY-55 (SEQ ID Nos: 2 and 15), CPN100709 RY-57 (SEQ ID Nos: 3 and 16), CPN100710 RY-58 (SEQ ID Nos: 4 and 17), CPN100711 RY-59 (SEQ ID Nos: 5 and 18), CPN100877 RY-61 (SEQ ID Nos: 6 and 19), CPN100325 RY-62 (SEQ ID Nos: 7 and 20), CPN100368 RY-63 (SEQ ID Nos: 8 and 21), CPN100624 RY-64 (SEQ ID Nos:9 and 22), CPN100633 RY-65 (SEQ ID Nos:10 and 23), CPN100985 RY-66 (SEQ ID Nos:11 and 24), CPN100987 RY-67 (SEQ ID Nos:12 and 25) and CPN100988 RY-68 (SEQ ID Nos:13 and 26).