Design and evaluation of a multi-epitope vaccine for COVID- 19: an in silico approach

Background & Aims: Corona virus disease-19 (COVID-19) is an evolving global disease which has burst into 2019. SARS-CoV-2 infects human cells
through recognition of and binding to angiotensin converting enzyme-2 (ACE2) through the spike (S) glycoprotein. Spike is an immunogenic protein
that can elicit immune responses. Multi-epitope vaccines are novel and efficient class of vaccines which are designed by linking the B and T cells. These
epitopes stimulate both humoral and cellular immunity.
Materials & Methods: Based on bioinformatics online tools, appropriate epitopes of S protein were selected, linked together via suitable linkers, a
TLR4 binding adjuvant was added, and a multi-epitope construct was constructed. The 3D model of the construct was predicted, refined, and validated.
The antigenicity, allergenicity, solubility, and physico-chemical properties of vaccine were checked. The B cell conformational epitopes and IFN-γ
inducing parts were detected. The adjuvant and TLR4 binding were evaluated by docking and protein-protein complex stability was assessed by elastic-
mode analysis. The coding sequence of the vaccine construct was optimized and sub-cloned in expression vector through an in silico approach. Finally,
the structure, energy, and stability of vaccine coding mRNA were evaluated.
Results: Ten continuous B cell epitopes, 9 T helper epitopes, and 8 CTL epitopes were chosen. The results showed that multi-epitope vaccine is a stable
and soluble protein which can stimulate humoral and cellular immunity. Besides, the vaccine could stimulate immunity without inducing allergenicity
in human body.
Conclusion: Finally, the vaccine can bind the TLR4 appropriately and can be expressed by a recombinant vector. The designed multi-epitope vaccine
against COVID-19 could be considered as a suitable candidate for experimental studie