Anti-C. trachomatis MOMP Monoclonal antibody, Clone 214

DNA encoding the major outer membrane protein (MOMP) of the koala type-I strain of Chlamydia psittaci (pathogen responsible for blindness and infertility in koalas) was cloned and sequenced. Comparison with momp gene sequences from other chlamydial species revealed a remarkable degree of homology (> 97%) with that of the human pathogen, Chlamydia pneumoniae. In comparison, the sequence only shared 75% DNA sequence homology with other C. psittaci members and 69% homology with C. trachomatis. The open reading frame consisted of 1167 bp encoding a 389-amino acid (aa) pre-MOMP including a leader sequence of 23 aa, similar to the C. pneumoniae gene. These genes were closely related even within the four variable domains (86-100% homology). Specific antibodies were capable of distinguishing between koala type I and C. pneumoniae. This very high degree of relatedness between C. pneumoniae, a human pathogen, and an individual strain of C. psittaci in the momp gene raises further questions on the host specificity, classification and evolutionary relationships of the different chlamydial species.

The amino acid sequence of the Chlamydia trachomatis major outer membrane protein (MOMP) has been modeled using a series of recombinant proteins containing MOMP fragments with lengths of 100 amino acids and overlaps of 30 amino acids. Testing of recombinant antigens in the immune enzyme analysis has shown that the proteins containing MOMP fragments of 191-286 and from 191-354 amino acids have had the greatest activity in the reaction with the anti-C. trachomatis-positive sera. The obtained data allow us to reach conclusions regarding the possibility of applying the presented recombinant proteins to develop a diagnostic test for detecting anti-C. trachomatis antibodies.