Elimination of Covid-19

INTRODUCTIONOver the past 2 decades, coronaviruses (CoVs) have been associated with significantdisease outbreaks in East Asia and the Middle East. The severe acute respiratorysyndrome (SARS) and the Middle East respiratory syndrome (MERS) began toemerge in 2002 and 2012, respectively. Recently, a novel coronavirus, severe acuterespiratory syndrome coronavirus 2 (SARS-CoV-2), causing coronavirus disease2019 (COVID-19), emerged in late 2019, and it has posed a global health threat, causing an ongoing pandemic in many countries and territories (1).
Health workers worldwide are currently making efforts to control furtherdisease outbreaks caused by the novel COV (originally named 2019-nCoV), whichwas first identified in Wuhan City, Hubei Province, China, on 12 December 2019. OnI l February 2020, the World Health Organization (WHO) announced the officialdesignation for the current CoV-associated disease to be COVID-19, caused bySARS-CoV-2. The primary cluster of patients was found to be connected with theHuanan South China Seafood Market in Wuhan (2).
COVs belong to the familyCoronaviridae (subfamily Coronavirinae), the members of which infect a broadtrunerlc Sl locates itsell on top 01 the S 2 stalk (45). Recently, structural analyses ofthe S proteins of COVID-19 have revealed 27 amino acid substitutions within a1, 273-ammo-acld stretch (16)Six substitutions are located in the RBI) (amino acids357 to 528), while four substitutions are in the RBM at the CTD of the Sl domain(16).
Of note, no amino acid change is seen in the RBM, which binds directly to theangiotensin-converting enzyme-2 (ACE2) receptor in SARS-CoV (16, 46). Atpresent, the main emphasis is knowing how many differences would be required tochange the host tropism. Sequence comparison revealed 17 nonsynonymous changesbetween the early sequence of SARS-CoV-2 and the later isolates of SARS-CoV, Thechanges were found scattered over the genome of the virus, with nine substitutions inORFlab, ORF8 (4 substitutions), the spike gene (3 substitutions), and ORF7a (singlesubstitution) (4).
Notably, the same nonsynonymous changes were found in a familialcluster, indicating that the viral evolution happened during person-to-persontransmission (4, 47). Such adaptive evolution events are frequent and constitute aconstantly ongoing process once the virus spreads among new hosts (47). Eventhough no functional changes occur in the virus associated with this adaptiveevolution, close monitoring of the viral absence of this protein IS related to thealtered virulence of coronaviruses due to changes in morphology and tropism (54).
The E protein consists of three domains, namely, a short hydrophilic amino terminal, a large hydrophobic transmembrane domain, and an efficient C-terminal domain (51). The SARS-CoV-2 E protein reveals a similar amino acid constitution without anysubstitution (16)