SARS-CoV-2 variants show a gradual declining pathogenicity and pro-inflammatory cytokine stimulation and an increasing antigenic and anti-inflammatory cytokine induction (preprint)

Hyper-transmissibility with decreased disease severity are typical characteristics of Omicron variant. To understand this phenomenon, we used various bioinformatics approaches to analyze randomly selected genome sequences (one each) of the Gamma, Delta, and Omicron variants submitted to NCBI from 15 to 31 December 2021. We show that: (i) Pathogenicity of SARS-CoV-2 variants decreases in the order: Wuhan > Gamma > Delta > Omicron; however, the antigenic property follows the order: Omicron > Gamma > Wuhan > Delta. (ii) Omicron Spike RBD has lower pathogenicity but higher antigenicity than that of other variants. (iii) Decreased disease severity by Omicron variant may be due to its decreased pro-inflammatory and IL-6 stimulation and increased IFN-{gamma} and IL-4 induction efficacy. (iv) Mutations in N protein are associated with decreased IL-6 induction and human DDX21-mediated increased IL-4 production in Omicron. (v) Due to mutations, the stability of S, M, N, and E proteins decrease in the order: Omicron > Gamma > Delta > Wuhan. (vi) Stronger Spike-hACE2 binding in Omicron is associated with its increased transmissibility. However, the lowest stability of the Omicron Spike protein makes Spike-hACE2 interaction unstable for systemic infection and for causing severe disease. Finally (vii), the highest instability of Omicron E protein may also be associated with decreased viral maturation and low viral load leading to less severe disease and faster recovery. Our method may be used for other similar viruses, and these findings will contribute to the understanding of the dynamics of SARS-CoV-2 variants and the management of emerging variants.

Molecular dynamics simulation and docking studies reveal NF-κB as a promising therapeutic drug target for COVID-19 (preprint)

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is rampant worldwide and is a deadly disease for humans. Our current work emphasizes on molecular dynamics simulation (MDS) targeting nuclear factor-kappa B (NF-κB), the well-known human transcription factor controlling innate and adaptive immunity, to understand its mechanism of action during COVID-19 in humans. NF-κB was interacted with the SARS-CoV-2 spike protein in an in silico MDS experiment, revealing the NF-κB site at which the SARS-CoV-2 spike protein interacts. We screened some known drugs via docking studies on NF-κB used as a receptor. The MDS software Schrodinger generated more than 2000 complexes from these compounds and using the SMILES format of these complexes, 243 structures were extracted and 411 conformers were generated. The drug used as a ligand that docked with NF-κB with the best docking score and binding affinity was Sulindac sodium as its trade name. Furthermore, RMSF data of sulindac sodium and NF-κB displayed minimal fluctuations in the protein structures, and the protein-ligand complex had reduced flexibility. Sulindac sodium is hence suggested as a suitable drug candidate for repurposing in clinical trials for SARS-CoV-2 infections. This drug potently blocked the spike protein’s interaction with NF-κB by inducing a conformational change in the latter. Arguably, NF-κB inaction is desired to have normal immunity and can possibly be retained using proposed drug. This work provides a significant lead for drug repurposing to combat SARS-CoV-2 and its various mutant forms and reveals new approach for controlling SARS-CoV-2-induced disease.