Objective: To analyze the antigenic cross reactivity of various proteins of strains of Chlamydia pecorum, C psitaci, and C trachomatis. SAMPLES AND PROCEDURES: Strains FC-Stra and LW-613 of C pecorum, strains B577, Fitz-9, and 68C of C psitaci, and strain LGV-2 of C trachomatis were studied. Strains of C pecorum were propagated in Georgia bovine kidney cells, and other chlamydial strains were propagated in L cells or Georgia bovine kidney cells. Partially purified chlamydial elementary bodies propagated in RAG cells, a BALB/c cell line cloned from a renal adenocarcinoma of BALB/c mice, were used to immunize BALB/c mice for production of monoclonal antibodies. Rabbits were inoculated with yolk sack-propagated, purified elementary bodies to produced polyclonal antisera. The reaction of monoclonal antibodies and polyclonal antisera with chlamydial proteins was analyzed by use of immunoblot techniques.
Results: Two monoclonal antibodies reacted with a 90-kd protein of C psittaci and a 94-kd protein of C pecorum strains. One monoclonal antibody reacted strongly with a 67-kd protein of C pecorum and strain B577 of C psittaci, but weakly with proteins of strains 6BC and LGV-2. Another monoclonal antibody reacted with a 46-kd protein of 2 C pecorum strains and of strain B577 of psittaci, but not with those of strains 6BC and LGV-2. Two monoclonal antibodies reacted with a 20-kd protein of C pecorum and a 22-kd protein of C psittaci and LGV-2 strains. Polyclonal antisera reacted similarly with the proteins identified by monoclonal antibodies in the various chlamydial strains.
Conclusions: Reactions of several monoclonal antibodies with chlamydial antigens indicated that 67- and 46-kd proteins contain genus- and species-specific epitopes, respectively; a 94-kd protein of C pecorum is homologous to a 90-kd protein of C psittaci and C trachomatis strains; and a 20-kd protein of C pecorum corresponds to a 22-kd protein of C psittaci and C trachomatis.