Quasispecies Feature in SARS –CoV-2

Abstract

Since the identification of the SARS CoV 2 genus Beta Coronavirus in January 2020 the virus quickly spread in less than 3 months to all continents with a susceptible human population of about a 7.9 billion, and still in active circulation. In the process, it has accumulated mutations leading to genetic diversity. Regular emergence of variants of concern/significance in different ecology shows genetic heterogeneity in the base population of SARS CoV 2 that is continuously expanding with the passage of the virus in the vast susceptible human population. Natural selection of mutant occurs frequently in a positive sense single stranded (ss) RNA virus upon replication in the host. The Pressure of sub optimal levels of virus neutralizing antibodies and also innate immunity influence the process of genetic or antigenic selection. The fittest of the mutants, that could be more than one, propagate and emerge as variants. The existence of different lineages, clades, and strains as well as genetic heterogeneity of plaque purified virus population justifies SARS CoV 2 as Quasispecies that refers to swarms of mutant sequences generated during replication of the viral genome and all mutant sequences may not lead to virion. Viruses having a quasispecies nature may end up with progressive antigenic changes leading to antigenic plurality that is driven by ecology and this phenomenon challenges vaccination based control programs