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)