The present invention is directed to providing a vaccine to enhance the immune response of an animal in need of protection against a Chlamydia infection. The present invention is also directed toward an isolated nucleic acid encoding a polypeptide comprising at least 70% identity to any one of SEQ ID NOS: 2, 11, 13, 19, or 21, wherein the polypeptide is soluble in the absence of denaturing agents. In some aspects of the invention, the polynucleotide is codon-optimized. In some embodiments, the present invention is related to the polypeptide encoded by the polynucleotide of the invention. Administration of polypeptides of the present invention can be used as a method to treat or prevent a Chlamydia infection in an animal in need thereof.
