Designing a multi-epitope vaccine against Chlamydia pneumoniae by integrating the core proteomics, subtractive proteomics and reverse vaccinology-based immunoinformatics approaches.

Chlamydia pneumoniae, a pneumonia causing specie belonging to chlamydia bacterium. C. pneumonia is considered as a leading cause of pneumonia. Apart from that, C. pneumoniae infection can also cause a variety of inflammatory disorders. There is an urgent need to tackle the major concerns arises due to infections causing by C. pneumoniae as no licensed vaccine available against this bacterial infection. In the framework of this study, a core proteome was generated C. pneumoniae strains was generated which revealed a total of 4754 core proteins. Later, 4 target proteins were obtained from 4754 core proteins by applying subtractive proteomics pipeline. Finally, MEV construct was designed by applying reverse vaccinology-based immunoinformatics approach on four target proteins. Molecular docking analysis were conducted to better understand thermodynamic stability, binding affinities, and interaction of vaccine. The binding interactions of MEV construct against TLR4, MHCII and MHCII showed that these candidate vaccines perfectly fit into the binding domains of the receptors. In addition, MEV construct has a better binding energy of 103.7 ± 15.4, 72.1 ± 9.1, and 70.4 ± 16.0 kcal/mol against TLR4, MHCII and MHCI. MD simulation was run at 200ns on docked complexes which further strengthened the current findings. Respective codon of vaccine construct was optimized and then in silico cloned into an E. coli expression host to ensure maximum vaccine protein expression. Despite the fact that the in-silico analysis used in this research produced reliable results, more studies are needed to validate the effectiveness and performance of proposed vaccine candidate.