PT  - JOURNAL ARTICLE
AU  - Suresh Kumar
AU  - Thiviya S. Thambiraja
AU  - Kalimuthu Karuppanan
AU  - Gunasekaran Subramaniam
TI  - Omicron and Delta Variant of SARS-CoV-2: A Comparative Computational Study of Spike protein
AID  - 10.1101/2021.12.02.470946
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.12.02.470946
4099  - http://biorxiv.org/content/early/2021/12/03/2021.12.02.470946.short
4100  - http://biorxiv.org/content/early/2021/12/03/2021.12.02.470946.full
AB  - Emerging SARS-CoV-2 variants, especially those of concern, may have an impact on the virus’s transmissibility and pathogenicity, as well as diagnostic equipment performance and vaccine effectiveness. Even though the SARS-CoV-2 Delta variant (B.1.617.2) emerged during India’s second wave of infections, Delta variants have grown dominant internationally and are still evolving. On November 26, 2021, WHO identified the variant B.1.1.529 as a variant of concern, naming it Omicron, based on evidence that Omicron contains numerous mutations that may influence its behaviour. However, the mode of transmission and severity of the Omicron variant remains unknown. We used computational studies to examine the Delta and Omicron variants in this work and found that the Omicron variant had a higher affinity for human ACE2 than the Delta variant due to a significant number of mutations in the SARS-CoV-2 receptor binding domain, indicating a higher potential for transmission. Based on docking studies, the Q493R, N501Y, S371L, S373P, S375F, Q498R, and T478K mutations contribute significantly to high binding affinity with human ACE2. In comparison to the Delta variant, both the entire spike protein and the RBD in Omicron include a high proportion of hydrophobic amino acids such as leucine and phenylalanine. These amino acids are located within the protein’s core and are required for structural stability. Omicron has a higher percentage of alpha-helix structure than the Delta variant in both whole spike protein and RBD, indicating that it has a more stable structure. We observed a disorder-order transition in the Omicron variant between spike protein RBD regions 468-473, and it may be significant in the influence of disordered residues/regions on spike protein stability and binding to ACE2. A future study might investigate the epidemiological and biological consequences of the Omicron variant.Competing Interest StatementThe authors have declared no competing interest.