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Immunoinformatic analysis of structural and epitope variations in the spike and Orf8 proteins of SARS-CoV-2/B.1.1.7.

ABSTRACT: A newly emerged strain of SARS-CoV-2 of B.1.1.7 lineage has caused a significant surge in the SARS-CoV-2 infections in the UK. In this study, changes in the epitopes of spike and orf8 proteins in SARS-CoV-2 of B.1.1.7 lineage were investigated. Genomic alignment of the SARS-CoV-2/B.1.1.7 with SARS-CoV-2/Wuhan showed the presence of several mutations in orf1a/b, spike, orf8, and N proteins of SARS-CoV-2/B.1.1.7. Molecular models of spike and orf8 proteins were constructed by homology modeling. Superimposition between the spike proteins of SARS-CoV-2/Wuhan and SARS-CoV-2/B.1.1.7 showed noticeable variations in the spatial orientation in Val70-Asn74 and Thr250-Ser255 regions. This may have also resulted in the extension of the epitopic region at Ser244-Gly249 in the SARS-CoV-2/B.1.1.7 spike protein. Superimposition of the SARS-CoV-2/B.1.1.7 spike protein over Fab-spike protein complexes of SARS-CoV-2/Wuhan also showed subtle variations in the antibody binding affinity targeting the N-terminal domain of the spike protein. Epitopic variations were also observed between the corresponding orf8 regions of SARS-CoV-2/Wuhan and SARS-CoV-2/B.1.1.7. Moreover, the presence of a stop codon at position 27 in orf8 connotes the emergence of two frames (orf8a and orf8b) in SARS-CoV-2, which further hampers its extracellular secretion, and in turn, immunogenicity. The findings of the present study could further be used to develop targeted immunotherapeutics.

SUBMITTER: Hussain M

PROVIDER: S-EPMC8206967 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundDifferent quickly-developed vaccines are introduced against COVID-19 with inconclusive results especially against some recent variants. Eventually, somewhere COVID-19 cases decline and in some countries it revived with some new mutant-variants (i.e. D614G, Delta and Omicron).ObjectivesProposing a universal vaccination strategy by screening globally-conserved SARS-CoV-2 spike-epitopes.MethodsPresently, several conserved (186-countries) sequences including multiple-variants (ClustalX2) epitopic-regions (SVMTriP and IEDB) and in-silico mutants of SARS-CoV-2 spike-protein-fragments (Cut1-4) were screened for their stability against proteases, antigenicity (VaxiJen V2.0 and for glycosylation effects NetOGlyc-NetNGlyc), MHCI/II reactivity (IEDB-TOOLS) and CD4+ responses by molecular-docking (Haddock2.4/PatchDock). We also examined Molecular-Dynamic-Simulation (myPresto verson-5) of MHC-II 3LQZ with 3-Cuts and T-cell 2-molecules (1KGC/4JRX) with SM3-Cut. The MD-simulation was run with 5000-cycles after 300 k-heating/1-atm pressure adjustment for the system-equilibration. Finally, 1000 fs production was run.ResultsThe cut4-mutant (SRLFRKSNLKPFERD) showed the highest combined-score 48.23548 and Immunogenicity-Score of 92.0887. The core-sequence SRLFRKSNL showed the highest Median-Percentile-Rank (7-HLA-allele) of 19. CD4+ immunogenicity also confirms the representation of the CUT4TM2 epitope SRLFRKSNL by MHC Class II. The epitope YNYKYRLFR from CUT4 showed an IC50 of ∼30 nM with allele HLA-DRB1*11:01 and HLA-DRB5*01:01 with plenty H-bonding. Cut4 double-mutants strongly interact with the exposed T-cell surface and are facilitated by its receptors. The MD-simulation data suggest that TM2 has a maximum RMSD value of 1.7 Å, DM2 is at 1.55 Å and SM3 is at 1.5 Å. These variations correspond to structural adjustments and involve binding/unbinding chemical interactions. The RMSD plot shows that 1KGC T-cell molecule is at 2.2 Å and the 4JRX is at 1.2 Å, which increases with the simulation time.ConclusionsScreening of conserved SARS-CoV-2 spike fragments helps to find the most stable antigenic-determinant which with some mutations showed better antigenicity. Further studies are necessary to develop global vaccination strategies against COVID-19.

Project description:A novel infectious agent, SARS-CoV-2, is responsible for causing the severe respiratory disease COVID-19 and death in humans. Spike glycoprotein plays a key role in viral particles entering host cells, mediating receptor recognition and membrane fusion, and are considered useful targets for antiviral vaccine candidates. Therefore, computational techniques can be used to design a safe, antigenic, immunogenic, and stable vaccine against this pathogen. Drawing upon the structure of the S glycoprotein, we are trying to develop a potent multi-epitope subunit vaccine against SARS-CoV-2. The vaccine was designed based on cytotoxic T-lymphocyte and helper T-lymphocyte epitopes with an N-terminal adjuvant via conducting immune filters and an extensive immunoinformatic investigation. The safety and immunogenicity of the designed vaccine were further evaluated via using various physicochemical, allergenic, and antigenic characteristics. Vaccine-target (toll-like receptors: TLR2 and TLR4) interactions, binding affinities, and dynamical stabilities were inspected through molecular docking and molecular dynamic (MD) simulation methods. Moreover, MD simulations for dimeric TLRs/vaccine in the membrane-aqueous environment were performed to understand the differential domain organization of TLRs/vaccine. Further, dynamical behaviors of vaccine/TLR systems were inspected via identifying the key residues (named HUB nodes) that control interaction stability and provide a clear molecular mechanism. The obtained results from molecular docking and MD simulation revealed a strong and stable interaction between vaccine and TLRs. The vaccine's ability to stimulate the immune response was assessed by using computational immune simulation. This predicted a significant level of cytotoxic T cell and helper T cell activation, as well as IgG, interleukin 2, and interferon-gamma production. This study shows that the designed vaccine is structurally and dynamically stable and can trigger an effective immune response against viral infections.

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Immunoinformatic analysis of structural and epitope variations in the spike and Orf8 proteins of SARS-CoV-2/B.1.1.7.

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