Introduction
A new type of viral pneumonia cases occurred in Wuhan, Hubei Province in
China, on December 31, 2019; named ”COVID-19” on January 12, 2020 by the
World Health Organization (WHO) [1]. Approximately, 292,893 people
died as a result of the COVID-19 outbreak, 4,342,685 cases had been
confirmed in 212 countries and territories till May 13, 2020. The
fatality rate of COVID-19 remains under assessment [2]. However,
infections of human coronavirus had resulted in lethal endemics, which
include endemic SARS (Severe Acute Respiratory Syndrome) and MERS
(Middle East Respiratory Syndrome) [3]. CoV infection begins with
the interaction of the receptor binding domain located in the spike
protein (S protein) and target receptor on the host cell surface, such
as, Angiotensin Converting Enzyme 2 (ACE2) for SARS-CoV and Dipeptidyl
Peptidase-4 (DPP4) for MERS-CoV [4]. Compared to SARS-CoV, the novel
coronavirus (2019-nCoV) uses ACE2 as its host-entry receptor. Binding
between the receptor-binding domain in S protein and the cellular
receptor, mediates membrane fusion and starts the COVID-19 life cycle
[5]. S protein on the viral membrane plays a critical role in virus
entry and is the key antigenic factor responsible for inducing the
immune response of the host [6]. For 2019-nCoV, in addition to
knowing the COVID-19 Spike protein (S protein) sequences (GenBank:
MN908947.3), there are no studies on how immunogenic this specific
protein can go beyond surrogate comparisons to SARS and MERS, which
restrict the possible capacity to generate a vaccine quickly [7].
Since it is a respiratory syndrome that has never been seen before and
with the potential to spread extensively and rapidly, it gained the
attention of the world but without the manual of treatment and
management [8]. Several national and international research groups
are working on vaccine production and drug repurposing to prevent and
treat the 2019-nCoV, but successful vaccines and drugs are still not
available. Active prevention and drug discoveries approaches for the
2019-nCoV outbreak are urgently needed [9, 10]. This review will
offer an accumulate information to the scientific research community
about numerous potential candidates of repurposable drugs that can
provide a synergistic effect in potentially treating
2019-nCoV/SARS-CoV-2.