Variants of SARS CoV-2: mutations, transmissibility, virulence, drug resistance, and antibody/vaccine sensitivity

Abstract

Severe acute respiratory syndrom coronavirus-2 (SARS CoV-2) is the causative agent of coronavirus disease-19 which has been designated a worldwide pandemic by the World Health Organization on March 11, 2020. Since that time, the virus has mutated and an assortment of variants have been successful at establishing themselves in the human population. This review article describes the SARS CoV-2 genome, hot spot mutations, variants, and then focuses on the Delta variant, finishing up with an update on the Omicron variant. The genome encompasses 11 open reading frames, one of which encodes the spike or S protein that has been the target for vaccines and some of the drugs because of its role in attachment to the human host cell, as well as antibodies. Mutations in the S protein that are common among several of the variants include D614G that increases transmissibility and viral load and is often associated with P323L on the RNA dependent RNA polymerase. N501Y is a mutation in the receptor binding domain of the S protein that increases binding to the ACE-2 receptor on the human host cells by 10 fold. The discussed variants carry combinations of these and other mutations and are classified by the World Health Organization as variants of concern, variants of interest, and variants under monitoring. All variants are characterized by increased transmissibility (relative to the original SARS CoV-2), which is the reason for their ability to establish themselves. Several but not all variants are more resistant to antiviral drugs and less susceptible to antibodies/vaccines. The Delta variant that dominated the world until November 2021 causes an increased risk for hospitalization and death, but is still very susceptible to the current vaccines. The most recent variant, Omicron, is characterized by increased transmissibility and decreased antibody susceptibility.

SARS CoV-2 (Delta Variant) Infection Kinetics and Immunopathogenesis in Domestic Cats

“…The clinical signs and histopathology were similar to that seen in our previous study, which utilized wildtype SARS-CoV-2 at about 10 times the dose of the Delta variant used in this study [26]. Based on these findings, the Delta variant of SARS-CoV-2 significantly more virulent than the original lineages in the domestic cat, similar to the increased virulence of the Delta variance in humans [55].…”

Association of Clinical Features with Spike Glycoprotein Mutations in Iranian COVID-19 Patients

“…There was no significant relationship between disease symptoms and D614G mutation in this study. D614G also is common among several of the variants of SARS-CoV-2 and increases transmissibility and viral load [ 13 , 31 ]. Also, in India, the spike D614G mutation has become the most common variant since December 2019.…”

Neutralisation of SARS-CoV-2 by monoclonal antibody through dual targeting powder formulation

“…Highly contagious viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are easily spread by patients with mild symptoms inadvertently, causing potentially fatal outcomes in patients with weak immune systems or comorbidities [ 1 ]. Despite rapid vaccine development and global health measures, the continual emergence of new mutant variants hinders the control of viral spread, rendering current treatment options ineffective [ 2 , 3 ]. Variants with enhanced resistance and transmissibility highlight the importance of implementing new approaches for prevention and treatment of COVID-19.…”