Coronaviruses is associated with three big public health nightmares in the
21st century globally, such as acute respiratory syndrome coronavirus (SARS-CoV, in
2002), Middle East respiratory syndrome coronavirus (MERS-CoV, in 2012), and
severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2, in 2020). They
have caused respiratory diseases in humans, particularly in the elderly, children, and
pre-existing comorbidities and immunocompromised patients. SARS-CoV-2 was first
recorded in Wuhan city, Hubei Province, Chinathat severely affecting the world
economy by more than $1 trillion. It consists of an enveloped lipid bilayer and a
positive-sense RNA genome. The genome size is approximately 30 kb. The SARSCoV-
2 structure consists of many essential proteins such as spike glycoprotein (S),
membrane (M), envelope (E), and nucleocapsid (NC). This chapter highlights the
updated knowledge of SARS-CoV-2 infections such as current and background history,
phylogenetic tree analysis of SARS-CoV-2, expression of ACE2 genes in human
tissues, phylogenic of S surface glycoprotein gene, M protein, E protein, NC protein,
evolutionary resemblance/comparison with SARS-CoV-2 and MERS gene, the role of
replication of novel strain lead to COVID-19, factors involve in COVID-19
pathogenesis and conserved and non-conserved gene of SARS-CoV-2. This study may
be a little supportive of the battle against COVID-19 infection worldwide.
Keywords: ACE2, Evolution, Genome, Replication, SARS-CoV-2, Spike protein.
