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ABSTRAK Felix Hojaya
PUBLIC Irwan Sofiyan

Chlamydia trachomatis is a Gram-negative intracellular obligate bacteria known to be the leading causes of sexually transmitted diseases in the world. Chlamydial infections could lead to serious health complications such as pelvic inflammation, ectopic pregnancy, and infertility. Unfortunately, most infections are usually asymptomatic and there have been found various antibiotic resistance cases. Vaccination is deemed as one of the best approaches to reduce chlamydial infection prevalence rather than screening or treatment with antibiotics. Up until now, no chlamydial vaccine is available. On the other hand, C. trachomatis outer membranes have been known to induce immune reaction. Therefore, in this study an attempt is made to design a vaccine from outer membrane using reverse vaccinology approach. Protein sequences collected from NCBI, and then followed with Multiple Sequence Alignment to determine epitope fragment candidates. CTL, HTL, and B cell epitope identification were done using different servers namely NetCTL v1.2, NetMHCII v2.3, and iBCE-EL, respectively. 3D structure of the vaccine candidate was predicted using trRosetta server, refined using GalaxyRefine server, and validated using Zscore, ERRAT score, and Ramachandran plot analysis. Molecular docking analysis between vaccine and TLR-1/2 and TLR-4 as well as between epitope and MHC molecules were done using ClusPro 2.0 server and GalaxyPepDock server, respectively. Finally, codon optimization and insertion into plasmid to make sure an efficient cloning and expression were done using JCat server and SnapGene application, respectively. Based on in silico analysis, a 270aa multi-epitope vaccine candidate was successfully designed and constructed. The vaccine consists of 9 CTL epitopes, and 2 HTL and B cell epitopes. Vaccine’s 3D structure was validated as good based on Ramachandran favoured score, Z-score, and ERRAT score all fall between the accepted range which were 95%, -6.73, and 80.75, respectively. Molecular docking analysis showed that interaction between vaccine candidate and TLR molecules and between epitopes and MHC molecules can all occur spontaneously (energetically feasible). Lastly, codon sequence optimization and insertion into plasmid showed that vaccine could be expressed using E. coli K12 and CAI score 1. Vaccine candidate identified in this study has shown to be a potential vaccine to induce specific, both B cell and T cells, immune reaction to prevent chlamydial infection and its quality can be evaluated in the future in clinical as well as pre-clincal studies.