Introduction
The novel 2019 SARS-CoV-2 coronavirus which causes significant morbidity
and mortality has been declared a pandemic by the World Health
Organization (Chan et al., 2020). Due to the highly infectious nature of
this contagion, urgent and coordinated efforts are required to develop a
vaccine against SARS-CoV-2.
SARS-CoV-2 is genetically related to the SARS-CoV coronavirus which
infected 8096 in 25 countries around the world (Tang et al., 2020).
Coronaviruses are RNA viruses with characteristic spikes on their
envelopes resembling a crown-like structure (Siddell, 1995). They are
zoonotic and therefore most likely crossed from animals such as bats
into humans through intermediaries (Andersen, Rambaut, Lipkin, Holmes,
& Garry, 2020; Huynh et al., 2012; Lai, Bergna, Acciarri, Galli, &
Zehender, 2020). Clinical features of SARS-CoV-2 range from asymptomatic
to severe respiratory distress syndrome (Wu et al., 2020).
The mode entry of SARS-CoV-2 has been recently shown to be through its
direct interaction of the surface glycoprotein with human
angiotensin-converting enzyme 2 (hACE2) (Hoffmann et al., 2020; Yan et
al., 2020). This mode of entry is the same as hCoV-NL63 and SARS-CoV
coronaviruses (Hofmann et al., 2005; Kuba et al., 2005). The
receptor-binding domain of the surface glycoprotein was shown to be
important for the entry of SARS-CoV-2 into the host cells as evidence by
the crystal structure of the SARS-CoV-2 RBD domain in complex with hACE2
(Tai et al., 2020). Since the surface glycoprotein is surfaced exposed,
it makes an ideal candidate for the development of neutralizing
antibodies, therapeutic drug design and vaccine development (Ahmed,
Quadeer, & McKay, 2020). However, due to the emergence of high mutation
rates in RNA viruses, therapeutic modalities might be hampered (Elena &
Sanjuán, 2005). Furthermore, antigen drift as has been a problem in the
development of influenza vaccines needs to be considered in SARS-CoV-2
(Hensley et al., 2009).
This study analyzed the surface glycoprotein from emerging isolates of
SARS-CoV-2 sequenced globally. Mutations in several isolates were
detected from different geographical locations, which might have
important implications for vaccine design and therapeutic development.