1. Introduction
A new coronavirus pandemic broke out from Wuhan, China in December 2019
and is still spreading across the globe. The viral causative agent of
this infectious calamity was named SARS-CoV2, and the resulting disease
is known as coronavirus disease 2019 (COVID-19) [1]. On February 11,
2020, the World Health Organization (WHO) officially declared COVID-19
as a global pandemic [2]. The SARS-CoV2 is the seventh member of the
zoonotic family Coronaviridae , genus Betacoronavirus and
shows striking resemblance to the other previously identified members,
SARS-CoV and middle east respiratory syndrome coronavirus (MERS-CoV), of
this family [3]. All three viruses originate from bats and after
spending parts of their life cycle in the intermediate hosts (camels for
MERS-CoV, civets for SARS-CoV and likely scaly anteaters for SARS-CoV2)
are transmitted to humans and cause lethal diseases [4]. The
coronaviruses are generally spherical crown-like structures under
electron microscopy with an approximate diameter of 125 nm [5]. The
whole body consist of a single-stranded positive-sense RNA genome
entrapping by a helical nucleocapsid (N) and a borrowed envelope that
embrace momentous membrane (M), envelope (E), and especially spike (S)
proteins and coverages the remnants [6]. All coronaviruses exploit
the host angiotensin-converting enzyme 2 (ACE2) receptor for cellular
entry with the help of their S protein except that the SARS-CoV-2
tendency to the ACE2 has greatly increased and entailed higher
infectivity [7].