Concluding remarks
SARS-CoV-2 that causes an epidemical pneumonia outbreak in Wuhan is
evident to be a novel betacoronavirus that belongs to the subgenus
Sarbecovirus through various analysis(D. S. Hui et al., 2020; R. Lu et
al., 2020; Wong et al., 2019). Controlling its spread is becoming a more
and more urgent affair to deal with for the whole world. Though its
mortality rate is only about 2%, but still few treatment options is
available. Up to now, the treating
option constrained only in a few drugs (Remdesivir, Chloroquine,
Hydroxychloroquine, Favipiravir etc.), in addition to the Chinese herb
as well as convalescent plasma. More drugs are only roughly screened by
virtual screening, and they are still far from not achieving the minimum
standards for clinical treatment application. Also, the expected vaccine
was reported but it just started the very first trial and still needs
time to apply on a large scale. Before the full development of an ideal
preventive and/or treatment, it would be a tough time for the human
race.
It is worth noting that older men with SARS-CoV-2 infection and other
underlying diseases typically have a higher mortality rate than older
women or younger, much healthier patients;(Chen et al.; Huang et al.;
F.-S. Wang & Zhang, 2020) Further studies are still needed to determine
the relevant influencing factors for this finding.
As the SARS-CoV-2 belongs to Nidovirales together with other two
serious respiratory diseases, a comparison of its nucleotide sequence
and construction of a phylogenetic tree with SARS and MERS has been
done. The findings of these analyses indicated that the SARS-CoV-2 is
comparatively closer to SARS but still distinct from it.(R. Lu et al.,
2020; Wu et al., 2020; P. Zhou et al., 2020a) Evidence was provided that
the virus has molecular and structural changes as well as some sites
under positive pressure, and moreover, its Spike Glycoprotein and
nucleocapsid protein has mutated.(Benvenuto et al., 2020)
It’s widely believed that it is close to two bat-derived virus strains;
bat-SL-CoVZC45 and bat-SL-CoVZXC21.(Chan et al., 2020; R. Lu et al.,
2020; Zhu et al., 2020) But a finding from Zhou et al suggests the most
similar one is the bat-derived strain called RaTG13.(P. Zhou et al.,
2020a) Although the very origin of
this virus has been determined to be bats, but till now we still can’t
determine what kind of animal plays the role of the intermediate host,
some say pangolin, some say
others, leaving an issue that
needs a further investigation.
Deletion and mutation were detected in the C-terminal of S region of the
gene, meanwhile, some insertion and replacement were also detected in
its N-terminal. Three-dimensional modelling, structural analysis and
amino acid sequencing had together verified the receptor binding domain
is still capable of binding with
Angiotensin
converting enzyme 2 (ACE2), indicating the cell entry mechanism relying
on ACE2 still possible.(Chan et al., 2020; R. Lu et al., 2020; P. Zhou
et al., 2020a)
When studying the ORF1ab and RdRp gene, it was found that recombination
took place in 1b in bat-derived strains as it is indicated from the
phylogenetical analysis together with topological findings in ORF1ab.(R.
Lu et al., 2020; Wu et al., 2020) And by analysing the alignment of the
RdRp gene, it further confirmed that there is indeed some recombination
happened in the 1b of bats.(P. Zhou et al., 2020a)