Screening of immunodominant proteins for sensitive detection of Chlamydia trachomatis infection by serological test
Objective To detect the antibodies against recombinant chlamydial plasmid-encoded protein 3（rPgp3）,chlamydial protease-like activity factor（rCPAF）,Ct143 encoded protein（rCT143）, Ct101 encoded protein（rCT101）,Ct694 encoded protein（rCT694）,Ct813 encoded protein（rCT813）, Chlamydia membrane protein A（rIncA）,Ct875 encoded protein（rCT875）,major outer membrane protein （rMOMP）and heat shock protein 60（ rHsp60）in serum samples collected form patients with urogenital Chlamydia trachomatis（Ct）infection and to evaluate the antigenicity of those proteins. Methods The recombinant plasmids expressing the 10 proteins and a blank plasmid were transformed into E. coli BL21 strains,respectively. The transformed E. coli BL21 strains were induced by isopropyl β-D-1-thiogalactopyr-anoside（IPTG）to express recombinant proteins. The glutathione pre-coated 96-well ELISA plates were coa-ted with lysates. Serum samples were collected from 50 patients with Ct infection and 10 patients without Ct infection. ELISA was performed to detect the antibodies against 10 recombinant proteins. Results The anti-bodies against rPgp3,rCPAF,rCT143,rCT101,rCT694,rCT875,rCT813,rMOMP,rIncA and rHsp60 proteins were respectively detected in 44 cases（88% ）,38 cases（76% ）,37 cases（74% ）,36 cases （72% ）,33 cases（66% ）,31 cases（62% ）,30 cases（60% ）,26 cases（52% ）,24 cases（48% ）and 17 cases（34% ）out of 50 serum samples. No antibodies against 10 recombinant proteins were detected in the serum samples collected from patients without Ct infection. Conclusion The rPgp3 protein showed the strongest antigenicity among all of the studied proteins,followed by rCPAF and rCT143 proteins. The rHsp60 protein showed the lowest antigenicity. 
 
Key words: 
Chlamydia trachomatis; Immunodominant protein; Serological test