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The Viruses
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
An outer envelope protects many types of viruses. The viral envelope is essentially a membrane derived from the host cell which consists of a lipid bilayer with inserted virus encoded proteins. Such proteins are usually glycosylated by host cell enzymes and appear as “spikes” on the viral surface when viewed by electron microscopy (e.g., Figures 16.1 B and 16.1C). Except for some members of the poxvirus family, all enveloped viruses lose their infectivity following extraction of their lipid with ethyl ether. Naked, nonenveloped viruses are unaffected by treatment with ether. Thus, enveloped virus particles are often labile and lose infectivity unless conditions are present to preserve the integrity of the viral envelope. In addition, enveloped viruses are usually more susceptible to detergents that disrupt the lipid envelope.
SARS-CoV-2 Morphology, Genomic Organisation and Lifecycle
Published in Srijan Goswami, Chiranjeeb Dey, COVID-19 and SARS-CoV-2, 2022
Srijan Goswami, Ushmita Gupta Bakshi
The viral envelope is present just under the surface proteins and is the outermost layer of the virus derived from the host's cell membrane. Since the host's cell membrane is made up of phospholipids and proteins, the fundamental composition of the viral envelope is the same as the host cell membrane. The only distinguishing feature is that, in viruses, these membrane structures are incorporated with viral glycoproteins instead of host cell glycoproteins. The phospholipid-protein complex of the viral envelope gets denatured when treated with soap, which in turn destroys the virus. This is the reason that the World Health Organization recommended thorough handwashing with soap as an important preventive measure.
Current Epidemiological and Clinical Features of COVID-19; a Global Perspective From China
Published in William C. Cockerham, Geoffrey B. Cockerham, The COVID-19 Reader, 2020
Huilan Tu, Sheng Tu, Shiqi Gao, Anwen Shao, Jifang Sheng
SARS-CoV-2 was found to be a positive-sense, single-stranded RNA virus belonging to the Betacoronavirus B lineage and is closely related to the SARS-CoV virus.13 Full-length genome sequences were obtained and indicated that the SARS-CoV-2 genome shares 79.6% sequence identity with that of SARS-CoV.14 Notably, SARS-CoV-2 infects human lung alveolar epithelial cells through receptor-mediated endocytosis using angiotensin-converting enzyme II (ACE2) as an entry receptor. Attachment to the receptor mediates the subsequent fusion between the viral envelope and host cell membrane, thereby allowing viral entry into the host cell.15,16
COVID-19: a wreak havoc across the globe
Published in Archives of Physiology and Biochemistry, 2023
Heena Rehman, Md Iftekhar Ahmad
The shape of the coronavirus is variable from spherical, elliptical to pleomorphic form with the size of 125 nm as shown by cryo-electron tomography and cryo-electron microscopy (Neuman 2006, Bárcena et al. 2009). The characteristic feature of coronavirus is the presence of club or clove head-shaped spikes on the surface. The name of coronavirus is named after the presence of spikes (corona refers to the crown). Some of the common features of coronavirus are the presence of conserved genomic organisation with a large replicase gene preceded by structural and accessory genes; expression of non-structural genes by ribosomal frameshifting, several unique enzymatic activities encoded within replicase–transcriptase polyprotein, expression of the downstream gene by 3′ nested subgenomic messenger RNA (mRNA) (Strauss and Strauss 2008). The viral envelope is comprised of phospholipids, proteins and glycoproteins. The glycoprotein present on the surface of the envelope facilitates the identification and binding to the receptor. There are four proteins present on the surface of coronavirus, namely-spike (S), membrane (M), envelope (E), and haemagglutinin (HA) proteins (Figure 1).
Immunoinformatics-guided designing and in silico analysis of epitope-based polyvalent vaccines against multiple strains of human coronavirus (HCoV)
Published in Expert Review of Vaccines, 2022
Bishajit Sarkar, Md. Asad Ullah, Yusha Araf, Nafisa Nawal Islam, Umme Salma Zohora
Coronaviruses are a group of pathogenic viruses that mainly infect mammals and birds. These viruses cause diseases in the respiratory tract of humans, ranging from the common cold in otherwise healthy individuals to more serious and lethal conditions and even death [1,2]. The coronavirus family, also known as Coronaviridae, is the largest family of Nidovirales order. The coronavirus family consists of two subfamilies, Letovirinae and Orthocoronavirinae. Among these two subfamilies, the Orthocoronavirinae contains four genera, Alphacoronavirus, Betacoronavirus, Gammacoronavirus, and Deltacoronavirus. And among these four genera, the Alphacoronavirus and Betacoronavirus are known to cause diseases in humans [3]. Coronaviruses are enveloped viruses containing a positive-sense single stranded RNA genome. The genome of coronaviruses ranges from approximately 25 to 34 kb. The viral envelope comprises a lipid bilayer where the membrane (M) and spike (S) structural proteins are anchored [4,5].
Biochemical and immunological aspects of COVID-19 infection and therapeutical intervention of oral low dose cytokine therapy: a systematic review
Published in Immunopharmacology and Immunotoxicology, 2021
Ratheesh M, Sheethal S, Svenia P. Jose, Sony Rajan, Sulumol Thomas, Tariq Jagmag, Jayesh Tilwani
The structure of coronavirus consists of Spike (S), Membrane (M), Envelope (E) glycoproteins, Hemagglutinin esterase (HE) and nucleocapsid (N) protein (Figure 1). The viral envelope is a lipid bilayer in which the structural proteins, membrane (M), envelope (E) and spike (S) are anchored. There is also a shorter spike-like surface protein called Hemagglutinin esterase (HE) in the coronavirus subset (especially the members of betacoronavirus subgroup A) [7]. Previous studies reported that SARS-CoV-2 has close similarities with SAR-CoV. The S protein helps the virus to gain entry into the host cells and the surface unit of S protein will facilitate the binding of virus to the target receptor as well as priming of S protein by cellular protease. This permits the fusion of both viral and host cell membranes [8–10]. The similarity of SAR-CoV-2 with SARS-CoV shows that the novel coronavirus also uses the same Angiotensin converting enzyme 2 (ACE-2) receptor as its entry receptor and TMPRSS2 serine protease helps in S protein priming [11,12]. ACE 2 is a membrane protein which is present in almost all the organs but highly expressed in type 2 alveolar cells [13–15]. Likewise, it is also expressed on vascular endothelial cells and cardiac cells which may perhaps describe the cardiovascular complications that occur in some patients [5]. S protein of SARS-CoV-2 has high affinity to ACE-2 receptors and this helps the virus to be transmitted more effectively between humans [16,17].