Abstract: Certain Chlamydia proteins have been found to be infection-specific and to be associated primarily with the vegetative Reticulate Body form of Chlamydia rather than with the refractile Elementary Body form of Chlamydia. The invention includes a vaccine directed against the Reticulate Body form of Chlamydia comprising one or more infection-specific proteins, or fraction thereof; a method of using such a vaccine; a method of production of such a vaccine; a method for detection of infection-specific antibodies in a biological specimen; a method for detection of infection-specific antigens in a biological specimen and a method of using therapeutic agents specifically directed against infection-specific peptides, or the genes that code for such peptides, to treat chlamydial infection. The invention also includes the IncB, and IncC proteins of C. psittaci, and nucleotides encoding these proteins, ant the TroA, TroB and p242 proteins of C. trachomatis, and the nucleotides that encode polypeptides.