Abstract: Objective To construct the recombinant plasmid containing the major outer membrane protein(MOMP) gene of Chlamydia trachomatis and expres s MOMP protein in E.coli BL21.Methods The MOMP gene was amplified by polymerase chain reaction from the genome of Chlamydia trachomatis serovar D.The amplified fragment was directly inserted into pUCm-T vector and verified by DNA sequencing.MOMP gene was then subcloned into the prokaryotic expression vector pET-22 b(+).The recombinant protein of MOMP was purified by Ni-NTA affinity chromatogr aphy and identified by SDS-PAGE and Western blot.Results The MOMP gene, which is about 1200 bp, was successfully amplified and cloned.The DNA sequence of the cloned MOMP gene was the same as that published by the GenBank.SDS-PAGE analysis showed that the relative molecular weight of this fusion protein was about 47 kDa which was consistent with the theoretically predicted value, and the specificity of this recombinant protein was confirmed by Western blot.Conclusions The MOMP gene of Chlamydia trachomatis was successfully cloned and expressed in the prokaryotic expression system, which may lay the foundation for the development of Chlamydia trachomatis vaccine.

Key words: Chlamydia trachomatis, Bacterial outer membrane proteins, Gene expression