SARS-related coronavirus

1039: 2932: 3114: 2403: 2383: 2497: 478: 80: 55: 8574: 7309: 7297: 3128: 3055:. The various smaller mRNAs are transcripts from the last third of the virus genome which follows the reading frames ORF1a and ORF1b. These mRNAs are translated into the four structural proteins (S, E, M, and N) that will become part of the progeny virus particles and also eight other accessory proteins (orf3 to orf9b) which assist the virus. 6373:

The SARS-CoV can hijack two cellular proteolytic systems to ensure the adequate processing of its S protein. Cleavage of SARS-S can be facilitated by cathepsin L, a pH-dependent endo-/lysosomal host cell protease, upon uptake of virions into target cell endosomes (25). Alternatively, the type II

2923:. "Direct cleavage of IRF3 by NSP3 could explain the blunted Type-I IFN response seen during SARS-CoV-2 infections while NSP5 mediated cleavage of NLRP12 and TAB1 point to a molecular mechanism for enhanced production of IL-6 and inflammatory response observed in COVID-19 patients." 2417:

spherical particles with bulbous surface projections that form a corona around the particles in electron micrographs. The size of the virus particles is in the 80–90 nm range. The envelope of the virus in electron micrographs appears as a distinct pair of electron dense shells.

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Finally, these results, combined with those from previous work (33, 44), suggest that CoVs encode at least three proteins involved in fidelity (nsp12-RdRp, nsp14-ExoN, and nsp10), supporting the assembly of a multiprotein replicase-fidelity complex, as described previously

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Betacoronaviruses-b ancestors, meaning SARSr-CoVs ancestors, could have been historically hosted by the common ancestor of the Rhinolophidae and Hipposideridae and could have later evolved independently in the lineages leading towards Rhinolophidae and Hipposideridae

3374:"Ecoepidemiology and complete genome comparison of different strains of severe acute respiratory syndrome-related Rhinolophus bat coronavirus in China reveal bats as a reservoir for acute, self-limiting infection that allows recombination events" 6374:

transmembrane serine proteases (TTSPs) TMPRSS2 and HAT can activate SARS-S, presumably by cleavage of SARS-S at or close to the cell surface, and activation of SARS-S by TMPRSS2 allows for cathepsin L-independent cellular entry (26,–28).

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showed that the evolutionary branch composed of Bat coronavirus BtKY72 and BM48-31 was the base group of SARS–related CoVs evolutionary tree, which separated from other SARS–related CoVs earlier than SARS-CoV-1 and SARS-CoV-2.

550:. SARSr-CoV is similar to other coronaviruses in that its genome expression starts with translation by the host cell's ribosomes of its initial two large overlapping open reading frames (ORFs), 1a and 1b, both of which produce 3857:

Furthermore, subsequent phylogenetic analysis using both complete genome sequence and proteomic approaches, it was concluded that SARSr-CoV is probably an early split-off from the Betacoronavirus lineage ; See Figure

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Figure 2. Phylogenetic analysis of RNA-dependent RNA polymerases (Pol) of coronaviruses with complete genome sequences available. The tree was constructed by the neighbor-joining method and rooted using Breda virus

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S is activated and cleaved into the S1 and S2 subunits by other host proteases, such as transmembrane protease serine 2 (TMPRSS2) and TMPRSS11D, which enables cell surface non-endosomal virus entry at the plasma

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The functions of several of the viral proteins are known. ORFs 1a and 1b encode the replicase/transcriptase polyprotein, and later ORFs 2, 4, 5, and 9a encode, respectively, the four major structural proteins:

2896:, which cleave the polyproteins at different specific sites. The cleavage of polyprotein pp1ab yields 16 nonstructural proteins (nsp1 to nsp16). Product proteins include various replication proteins such as 3025:

of the RNA-dependent RNA polymerase. The coronaviruses require the increased fidelity and processivity during RNA synthesis because of the relatively large genome size in comparison to other RNA viruses.

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are present in a host cell, they may interact with each other to form recombinant genomes that can be transmitted to progeny viruses. Recombination likely occurs during genome replication when the

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Stanhope MJ, Brown JR, Amrine-Madsen H. Evidence from the evolutionary analysis of nucleotide sequences for a recombinant history of SARS-CoV. Infect Genet Evol. 2004 Mar;4(1):15-9. PMID 15019585

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The attachment of the SARS-related coronavirus to the host cell is mediated by the spike protein and its receptor. The spike protein receptor binding domain (RBD) recognizes and attaches to the

3098:. There, the M proteins direct most protein-protein interactions required for assembly of viruses following its binding to the nucleocapsid. Progeny viruses are released from the host cell by 7301: 6723:"SARS-CoV-2 proteases cleave IRF3 and critical modulators of inflammatory pathways (NLRP12 and TAB1): implications for disease presentation across species and the search for reservoir hosts" 3021:

function to the complex which the RNA-dependent RNA polymerase lacks. Similarly, proteins nsp7 and nsp8 form a hexadecameric sliding clamp as part of the complex which greatly increases the

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Zhang XW, Yap YL, Danchin A. Testing the hypothesis of a recombinant origin of the SARS-associated coronavirus. Arch Virol. 2005 Jan;150(1):1-20. Epub 2004 Oct 11. PMID 15480857

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The SARS-CoV genome is ~29.7 kb long and contains 14 open reading frames (ORFs) flanked by 5′ and 3′-untranslated regions of 265 and 342 nucleotides, respectively (Figure 1).

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The two SARS-CoV-2 proteases (PLpro and 3CLpro) also interfere with the immune system response to the viral infection by cleaving three immune system proteins. PLpro cleaves

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molecules from the positive-sense genomic RNA. This is followed by the transcription of these negative-sense subgenomic RNA molecules to their corresponding positive-sense

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Different SARS-CoV strains isolated from several hosts vary in their binding affinities for human ACE2 and consequently in their infectivity of human cells76,78 (Fig. 6b)

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of negative-sense genomic RNA from the positive-sense genomic RNA. This is followed by the replication of positive-sense genomic RNA from the negative-sense genomic RNA.

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Temmam S, Vongphayloth K, Baquero E, Munier S, Bonomi M, Regnault B, et al. (April 2022). "Bat coronaviruses related to SARS-CoV-2 and infectious for human cells".

6335:"TMPRSS2 and ADAM17 cleave ACE2 differentially and only proteolysis by TMPRSS2 augments entry driven by the severe acute respiratory syndrome coronavirus spike protein" 3878: 469:. Both of these strains descended from a single ancestor but made the cross-species jump into humans separately. SARS-CoV-2 is not a direct descendant of SARS-CoV-1. 5732:

Virions acquired an envelope by budding into the cisternae and formed mostly spherical, sometimes pleomorphic, particles that averaged 78 nm in diameter (Figure 1A).

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Nevertheless, the interaction between S protein and receptor remains the principal, if not sole, determinant of coronavirus host species range and tissue tropism.

4863:"Severe Acute Respiratory Syndrome (SARS) Coronavirus ORF8 Protein Is Acquired from SARS-Related Coronavirus from Greater Horseshoe Bats through Recombination" 3491:

Most notably, horseshoe bats were found to be the reservoir of SARS-like CoVs, while palm civet cats are considered to be the intermediate host for SARS-CoVs .

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of the spike protein triggers the fusion of the viral envelope with the host cell membrane by inducing conformational changes which are not fully understood.

4811:"Identification of diverse alphacoronaviruses and genomic characterization of a novel severe acute respiratory syndrome-like coronavirus from bats in China" 3184:

are sometimes used interchangeably, especially prior to the discovery of SARS-CoV-2. This may cause confusion when some publications refer to SARS-CoV-1 as

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Starr, Tyler N.; Zepeda, Samantha K.; Walls, Alexandra C.; Greaney, Allison J.; Alkhovsky, Sergey; Veesler, David; Bloom, Jesse D. (1 March 2022).

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Particle diameters ranged from 50 to 150 nm, excluding the spikes, with mean particle diameters of 82 to 94 nm; Also See Figure 1 for double shell.

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over a long period of time. Only recently have strains of SARS-related coronavirus been observed to have evolved into having been able to make the

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Lam TT, Jia N, Zhang YW, Shum MH, Jiang JF, Zhu HC, et al. (July 2020). "Identifying SARS-CoV-2-related coronaviruses in Malayan pangolins".

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Lau, Susanna K. P.; Feng, Yun; Chen, Honglin; Luk, Hayes K. H.; Yang, Wei-Hong; Li, Kenneth S. M.; Zhang, Yu-Zhen; Huang, Yi; et al. (2015).

1038: 450:. SARSr-CoV was determined to be an early split-off from the betacoronaviruses based on a set of conserved domains that it shares with the group. 11193: 8628: 8183: 7814: 2359: 1798: 466: 462: 316: 304: 223: 218: 5342:

Xiao K, Zhai J, Feng Y, Zhou N, Zhang X, Zou JJ, et al. (July 2020). "Isolation of SARS-CoV-2-related coronavirus from Malayan pangolins".

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Bats serve as the main host reservoir species for the SARS-related coronaviruses like SARS-CoV-1 and SARS-CoV-2. The virus has coevolved in the

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Xu, L; Zhang, F; Yang, W; Jiang, T; Lu, G; He, B; Li, X; Hu, T; Chen, G; Feng, Y; Zhang, Y; Fan, Q; Feng, J; Zhang, H; Tu, C (February 2016).

2514:(ACE2) receptor. Following attachment, the virus can enter the host cell by two different paths. The path the virus takes depends on the host 11206: 10918: 9428: 3238: 7269:

Enjuanes L, Sola I, Zúñiga S, Almazán F (2008). "Coronavirus Replication and Interaction with Host". In Mettenleiter TC, Sobrino F (eds.).

7199:"Rewiring the severe acute respiratory syndrome coronavirus (SARS-CoV) transcription circuit: engineering a recombination-resistant genome" 6946: