Designing and modeling of complex DNA vaccine based on MOMP of Chlamydia trachomatis: an in silico approach

Abstract

Chlamydia trachomatis (Ct) is an intracellular pathogen that causes ocular and genital tract infections. Vaccines have an important role in management of Ct-caused diseases. Major outer membrane protein (MOMP) is the most abundant and one of the most studied proteins for utilizing as a Ct vaccine candidate. In this study, there was an attempt to take advantage of in silico approach to design a safe, effective, and broad-spectrum polytopic vaccine against Ct. Complete putative sequences of MOMPs of Ct immunogenic serovars were retrieved and highly conserved/variable regions were found. At the next step, consensus and immuno-dominant CD8+ and CD4+ epitopes of the protein were designated. Then, to design the CD8+ T-cell construct, selected CD8+ T epitopes and tag sequences were arranged in an appropriate pattern while separated from each other by suitable linkers. Using the same strategy, CD4+ T-cell construct was created. Immunogenicity of each construct was improved. Next, for each construct, primary structure evaluation, hydrophobicity calculation, reverse translation, codon optimization, and insertions of Kozak sequence and stop codon were performed. 3D models of the constructs were determined. Potential B-cell epitopes were predicted from the surface of the modeled structures. Results showed that both constructs contain several linear and conformational B-cell epitopes, which signify their antibody triggering property. Docking analysis represented that each polytope is a better immunogenic candidate than its naked adjuvant.