key: cord-0724415-sbswy7el authors: Anand, K.B.; Karade, S.; Sen, S.; Gupta, R.M. title: SARS-CoV-2: Camazotz's Curse date: 2020-04-27 journal: Med J Armed Forces India DOI: 10.1016/j.mjafi.2020.04.008 sha: eccbbe49aacebe62e1b4c127406aace517118294 doc_id: 724415 cord_uid: sbswy7el The world is currently face to face with a pandemic which is spreading rapidly across the globe caused by SARS-CoV-2, a strain of Coronaviruses (CoVs) belonging to subgenus Sarbecovirus of genus Betacoronavirus. World Health Organisation (WHO) on 11 Feb 20 named this disease caused by SARS-CoV-2 as Covid-19. This pandemic is spreading rapidly and more than 20,00,000 cases have occurred globally. The human Coronaviruses discovered in 1960s were considered potentially harmless endemic viruses with seasonal distribution before late 2002. The CoVs are found in a large number of domestic and wild animals and birds. The first pandemic caused by Coronavirus caused by SARS-CoV was recognized in the late 2002 in Guangdong Province and resulted in widespread morbidity and mortality. This was followed by MERS-CoV which began in 2012 in the Arabian peninsula with multiple outbreaks related to it in various parts of the globe. Various studies have suggested how these viruses made their entry from their natural reservoir bats via intermediate host like civets and camels in case of SARS-CoV and MERS-CoV respectively. The intermediate host of the SARS-CoV-2 still needs to be established. The SARS-CoV-2 has 96.2% similarity to the bat Severe Acute Respiratory Syndrome related-Coronavirus (SARSr-CoV RaTG13). SARS-CoV-2 has been found to be more distant in relation to SARS-CoV (79%) and MERS-CoV (50%). At the whole genome sequence level pangolin CoV and SARSr-CoV RaTG13 show 91.02% and 96.2% similarity with SARS-CoV-2 but the S1 subunit of spike protein of pangolin CoV is more closely related to SARS-CoV-2 than SARSr-CoV RaTG13. The genetic analysis of the currently circulating strains of the pandemic have shown 99.98-100% similarity in their genomes implying a recent shift to humans. The animal source of SARS-CoV-2 needs to be identified to implement control measures in the present pandemic. Also, how the virus moves interspecies will help predict and prevent future pandemics. Till now Six human CoVs (HCoVs) have been confirmed: HCoV-NL63 and HCoV-229E, which belong to the alpha-coronavirus genus; and HCoV-OC43, HCoV-HKU1, SARS-CoV, and MERS-CoV, belong to the beta-coronavirus genus. SARS-CoV and MERS-CoV are the two major causes of severe pneumonia in humans. (5, (9) (10) (11) SARS-CoV 2 is the seventh CoV know to infect humans. SARS was the first known pandemic caused by a CoV. The disease got recognized in the late 2002 with the outbreak of acute atypical community acquired atypical pneumonia notice first at Guangdong Province and 29 countries got affected by the spread. (5, 9, 10) After the 2003 SARS-CoV pandemic resulted in widespread morbidity and mortality and same ended in Jun 2003. (9, 10) . This was followed by a novel CoV, which was There are studies to suggest that birds and bats are the natural reservoirs of the virus (2, 13, 14) . Coronaviruses also have a potential for interspecies transmission which can also cause zoonotic outbreaks. shower higher amino acid sequence identity to SARS-CoV-2 than to RaTG13 genes which included orf1b, spike protein(97.5% nucleotide identity), orf7a and orf10. The S1 protein which contains the RBD, is phylogenetically closer to pangolin-CoV than RaTG13 and this RBD region within the S1 was found to be conserved between Pangolin CoV and SARS-CoV2. The CoV spike (S) protein consisting of 2 subunits (S1 and S2), mediates infection of receptor-expressing host cells and the similarity between S1 protein of pangolin CoV to SARS-CoV2 points potential similarity in their pathogenic properties. (22) Though the origin of the SARS-CoV 2 is still a debatable topic but the recognition of the intermediate animal host is the crucial step in preventing further dissemination, future outbreaks and blocking the interspecies transmission. Although both SARS CoV2 and prior SARS-CoV utilize ACE2 receptors to invade respiratory epithelium, the magnitude of infections caused by SARS-CoV2 is enormous. We are still unable to pinpoint the original reservoir for SARS CoV2. SARS-CoV genome was found to be 99.8% similar to that from civet cats. The similarity of whole genome sequence of SARS CoV2 to pangolins is only 92% and 96.2% similarity to a bat SARS-related Coronavirus (SARSr-CoV; RaTG13) which is insufficient to prove beyond doubt that these are the source of the virus. SARS was a relatively rare disease and at the end of the epidemic more than 8000 cases had occurred from 01Nov 2002 to 31 Jul 2003 whereas the ongoing Covid 19 caused by SARS-CoV2 has already caused more than 20,00,000 cases across the globe in a span of approximately five months (26, 27) . Though the mode of spread of both the viruses is almost same, SARS COV2 is far more infectious than SARS-CoV and the reason for the same is yet to be established. The world today is facing a crisis due to the pandemic caused by SAR-CoV2. Based However, within these two types of SARS-CoV-2, L type (~ 70%) and S type (~ 30%) have been observed by Tang et al. The strains in L type is derived from S type. The L type as per the author's conclusion appears to be more virulent and contagious. (25) The human-animal interphase created by either encroachment of natural habitat of wild animals, maintaining domestic animals which get infected or consumption of animals which may be harbouring the viruses is the tipping point as per a large number of studies. It is important to understand viral dynamics so that future outbreaks can be avoided by active surveillance for these viruses. Regulations also need to be formulated to restrict the domestication as well as consumption of wild animals. A novel coronavirus genome identified in a cluster of pneumonia cases-Wuhan A novel coronavirus from patients with pneumonia in China The Proximal Origin of SARS-CoV-2 Cultivation of a novel type of common cold virus in organ cultures SARS and other coronaviruses as causes of pneumonia Coronaviruses: an overview of their replication and pathogenesis Virus taxonomy. Ninth report of the international committee on taxonomy of viruses Identification of a novel coronavirus in patients with severe acute respiratory syndrome A novel coronavirus associated with severe acute respiratory syndrome Current understanding of middle east respiratory syndrome coronavirus infection in human and animal models Identification and evolutionary dynamics of two novel human coronavirus OC43 genotypes associated with acute respiratory infections: phylogenetic, spatiotemporal and transmission network analyses. Emerg Microbes Infect Bats are natural reservoirs of SARS-like coronaviruses Evidence for an ancestral association of human coronavirus 229E with bats Human coronaviruses 229E and NL63: close yet still so far Link of a ubiquitous human coronavirus to dromedary camels Evolutionary dynamics of bovine coronaviruses: natural selection pattern of the spike gene implies adaptive evolution of the strains Evolutionary history of the closely related group 2 coronaviruses: porcine hemagglutinating encephalomyelitis virus, bovine coronavirus, and human coronavirus OC43 Discovery of seven novel mammalian and avian coronaviruses in the genus deltacoronavirus supports bat coronaviruses as the gene source of alphacoronavirus and betacoronavirus and avian coronaviruses as the gene source of gammacoronavirus and deltacoronavirus Genomic characterisation and epidemiology of 2019 novel coronavirus: implications for virus origins and receptor binding A pneumonia outbreak associated with a new coronavirus of probable bat origin Probable pangolin origin of SARS-CoV-2 associated with the COVID-19 outbreak Structure, function, and antigenicity of the SARS-CoV-2 spike glycoprotein Genetic predisposition to acquire a polybasic cleavage site for highly pathogenic avian influenza virus hemagglutinin On the origin and continuing evolution of SARS-CoV-2 Summary of probable SARS cases with onset of illness from 1 Coronavirus COVID-19 Global Cases by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU)". ArcGIS. Johns Hopkins CSSE. Retrieved 15 LC528232.1 SARS MH734115.1 MERS-CoV camel/Kenya/C1272/2018 NC 019843.3 MERS-CoV Beta-CoV