Perceptions into causes and consequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants are emerging worldwide and pathogenicity varies widely from no symptoms to death. The SARS-CoV-2 is evolving as lineages like Alpha, Beta, Gamma, Epsilon, Iota, Delta, and Omicron in the course of time. The main reasons for such viral evolution are (a) the imperfect nature of SARS-CoV-2 RNA polymerase, and viral exonuclease mediated proofreading functions resulting in the generation of mutations in viral genomes; (b) fusions of the 5 leader sequence to unexpected 3 sites, and transcription regulatory sequences (TRSs) in subgenomic RNAs (sgRNAs), which result in the generation of structural variants and novel open reading frames; (c) these viruses are combated by the host type I interferons (IFNs). In such a process IFNs upregulate viral RNA editing APOBEC3G/F and ADAR1 genes, which induce mutations in viral genomes. These factors play important roles in causing viral evolution and the emergence of more efficient SARS-CoV-2 genomes, which escape the host immune defense system, and vaccine-elicited antibodies and impede therapeutic strategies. The main challenges we now face are how to control future SARS-CoV-2 evolution, the elimination of their deleterious side effects, and the onset of new diseases as aftermaths of SARS-CoV-2 infections. Preventive measures like (a) the development of broadly neutralizing antibodies and novel vaccines, therapies based on genomics and proteomics data will help in avoiding, and/or minimizing SARS-CoV-2 infections; (b) targeted therapies, application of patient-based precision medicine methodology can help in achieving the goal and avoiding unwanted deleterious side effects and the onset of SARS-CoV-2 infections mediated several diseases in future.