![]() ![]() SARS-CoV-2 has been declared as a pandemic, with 1,844,683 confirmed cases and 117,021 deaths globally by 14th April 2020 (World Health Organization 2020). Both the viruses have been found to originate from bats and then transmitted into intermediate mammalian host civets in the case of SARS-CoV and camels in the case of MERS-CoV and eventually infected humans (Song et al. Since 2012, MERS-CoV has caused persistent epidemics in the Arabian Peninsula. In 2002–2003, SARS-CoV emerged in China with 8000 clinical cases and 800 deaths. HKU1, NL63, OC43, and 229E CoVs are associated with mild symptoms in humans, whereas severe acute respiratory syndrome CoV (SARS-CoV) and Middle East respiratory syndrome CoV (MERS-CoV) are known to cause severe disease (Fehr and Perlman 2015). The ability of CoVs to cross the species barrier has resulted in some of the pathogenic CoVs. Evolutionary trend analysis of coronaviruses has revealed that αCoV and βCoV originated from bats and rodents, while γCoV and δCoV were found to have originated from avian species (Ge et al. On the basis of genomic organization and phylogenetic relationship, coronaviruses have been classified into the subfamily Coronavirinae that consists of four genera Alphacoronavirus (αCoV), Betacoronavirus (βCoV), Gammacoronavirus (γCoV), and Deltacoronavirus (δCoV) (Cui et al. This chapter discusses about the morphology, genome organization, replication, and pathogenesis of SARS-CoV-2 that may help us understand the disease that may leads to identification of effective antiviral drugs and vaccines.Ĭoronaviruses (CoVs) are enveloped single-stranded positive sense RNA viruses that belong to the family Coronaviridae. Histopathological investigation of tissues from SARS-CoV-2 infected patients showed virus-induced cytopathic effect with signs of acute respiratory distress syndrome in lung cells. Like SARS-CoV, SARS-CoV-2 uses the ACE2 receptor for internalization and TMPRSS2 serine proteases for S protein priming. The structure of spike glycoprotein structure of SARS-CoV-2 resembles that of the spike protein of SARS-CoV with an root-mean-square deviation (RMSD) of 3.8 Å. The nsps includes two viral cysteine proteases including papain-like protease (nsp3), chymotrypsin-like, 3C-like, or main protease (nsp5), RNA-dependent RNA polymerase (nsp12), helicase (nsp13), and others likely to be involved in the transcription and replication of SARS-CoV-2. Sequence variation among SARS-CoV-2 and SARS-CoV revealed no significant difference in ORFs and nsps. The genome comprises of 6–11 open reading frames (ORFs) with 5′ and 3′ flanking untranslated regions (UTRs). Spike, membrane, and envelope surface viral proteins of coronavirus are embedded in host membrane-derived lipid bilayer encapsulating the helical nucleocapsid comprising viral RNA. The structure of SARS-CoV-2 is found to be similar to SARS-CoV with virion size ranging from 70 to 90 nm. Genomic characterization of SARS-CoV-2 has shown that it is of zoonotic origin. SARS-CoV-2 has recently emerged and has been declared as a pandemic by the World Health Organization. SARS-CoV-2 is a single-stranded RNA virus of ~30 kb genome size which belongs to genus Coronavirus and family Coronaviridae. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |