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The Viruses
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Poliovirus is a relatively small, naked icosahedral virus with a single stranded RNA genome. Its family, the Picornaviridae (Table 16.1) includes the rhinoviruses, which cause the common cold, and the hepatitis A virus, which causes acute liver disease. Man is the natural host of poliovirus. The virus infects primarily intestinal mucosal cells but may infect other cells, including neurons. The virus can be transmitted to the chimpanzee, and strains are available that infect mice.
Order Picornavirales
Published in Paul Pumpens, Peter Pushko, Philippe Le Mercier, Virus-Like Particles, 2022
Paul Pumpens, Peter Pushko, Philippe Le Mercier
Figure 27.1 presents typical portraits of the order representatives and schematic cartoons of members of the important families. The Caliciviridae virions possess icosahedral T = 3 symmetry and diameter of 27–40 nm, where smaller empty, so-called 23-nm particles with T = 1 symmetry were observed after the mature 38-nm virions. The T = 3 capsid is composed of 90 dimers of the major structural protein VP1. The Picornaviridae virions are 30–32 nm in diameter, possess T = 1 or pT = 3 symmetry, and consist of 60 identical protomers, each comprising four VP1-VP4 capsid proteins, in other words protein 1A and paralogous 1B, 1C, and 1D or three capsid proteins when 1AB remains uncleaved. The mature capsid proteins 1B, 1C, and 1D and the uncleaved 1AB possess a core structure of an eight-stranded β-barrel, also known as a “jelly roll” (Jiang P et al. 2014). The same structure is typical for the Secoviridae virions that are also of similar 25–30 nm in diameter. The capsid is built by large (CPL or simply L) and small (CPS or S) capsid proteins. Many virus preparations contain empty virus particles. In the case of viruses, such as CPMV, with a bipartite genome, the two RNAs are encapsidated in separate virions. Thus, the B-particle containing one molecule of RNA1 and the M-particle containing one molecule of RNA2 were identified (Thompson et al. 2017).
Enteroviruses
Published in Avindra Nath, Joseph R. Berger, Clinical Neurovirology, 2020
Karen Straube-West, Burk Jubelt
Enteroviruses are one of the five subfamilies (genera) in the family Picornaviridae. They are found in humans (human enteroviruses) and many animals and are species specific. The Picornaviridae are small RNA viruses, thus the term “picornavirus” was derived from “pico,” meaning very small, and “RNA” for the type of genomic nucleic acid. There are over 100 recognized enterovirus serotypes specific for humans (Table 17.1). The enteroviruses share a number of characteristics. They replicate at 37°C, lack a lipid envelope, and are stable at acid pH, which allows them to survive and replicate in the gastrointestinal tract. The virion is composed of a positive single strand of RNA of approximately 7400 nucleotides and a 3′ poly-A tail [1]. The polyprotein is translated into one long single protein, which is then cleaved to form all the individual viral proteins [2]. The capsid is an icosahedron (spheroidal) that is 22–30 nm in diameter and composed of four proteins. Three of them, VP1, VP2, and VP3, are each repeated 60 times and compose the external surface of the capsid. Once the virus completes the replication cycle it is generally released from the host cell via cell lysis, thus killing the infected cell. However, recent studies suggest that a solely lytic infection is not always the case in that the virus or at least viral RNA may persist for months or years after the acute infection [3].
The role of sialic acid-binding immunoglobulin-like-lectin-1 (siglec-1) in immunology and infectious disease
Published in International Reviews of Immunology, 2023
Shane Prenzler, Santosh Rudrawar, Mario Waespy, Sørge Kelm, Shailendra Anoopkumar-Dukie, Thomas Haselhorst
Rhinoviruses, single-stranded RNA viruses belong to the Picornaviridae family. Rhinovirus is believed to manipulate the expression of Siglec-1 on DCs by induction [25]. The induction of Siglec-1 expression on DCs results in an increased interaction between Siglec-1 and CD43 on T-cells impeding any adaptive immune response [25]. DCs that have undergone induction of Siglec-1 interfere with the appropriate recognition and activation of the T-cell from the antigen presenting cell [25]. Under normal circumstances CD43 receptors on T-cells relocate away to the opposite pole from the synapse between the antigen presenting cell and the T-cell allowing for interaction and activation of the T-cell [25]. Other inhibitory receptors are also present and upregulated during rhinovirus infection such as B7-H1 [25]. However, antibody studies showed that blocking of B7-H1 does not restore function of dendritic cells for the activation of T-cells and that both Siglec-1 and B7-H1 are required antibody blockade to see a restoration of function [25]. It is thought that such dysregulation of the adaptive immune system may increase the frequency of complications to rhinovirus such as otitis media, sinusitis, pneumonia and bronchitis [25, 55].
The design and discovery of phospholipase A2 inhibitors for the treatment of inflammatory diseases
Published in Expert Opinion on Drug Discovery, 2021
Charikleia S. Batsika, Anna-Dimitra D. Gerogiannopoulou, Christiana Mantzourani, Sofia Vasilakaki, George Kokotos
Coronaviruses (CoVs) are responsible for various respiratory and enteric diseases with differing pathogenicity in humans and animals. In 2017, a study was conducted exploring the relation of GIVA cPLA2 with coronaviruses. It was shown that the replication of various +RNA virus families is inextricably connected with the activity of GIVA cPLA2, suggesting a new direction for the development of broad-spectrum antiviral drugs. Inhibition of GIVA cPLA2 by the inhibitor RSC-3388 resulted in considerable effects on viral RNA and protein accumulation in human coronavirus 229E-infected Huh-7 cells [113]. This inhibitor also exhibited antiviral effect against other viruses belonging to the Coronaviridae and Togaviridae families, while it was found inactive against members of the Picornaviridae family. As a consequence, enzymes which are involved in cellular lipid metabolism, such as the various PLA2s, constitute a new target for the development of small-molecule inhibitors exhibiting antiviral activity.
The potential of plant-made vaccines to fight picornavirus
Published in Expert Review of Vaccines, 2020
Omayra C. Bolaños-Martínez, Sergio Rosales-Mendoza
Picornaviridae is one of the largest viral families, which according to the International Committee on Taxonomy of Viruses (ICTV) comprise 35 genera enclosing 80 viral species; many other are on the list to be classified. All members are ~30-32 nm in diameter with an icosahedral structure composed of 60 identical units (protomers) [1]. The members of this family have a genome composed of a single-stranded, positive-sense, and non-segmented RNA; with a length ranging 6.7–10.1 kb. The ORF is flanked by two untranslated regions (UTR); with the 5´end containing diverse RNA secondary structures implicated in replication and associated with the VPg protein that plays an important role in translation. The 3´UTR contains a poly (A) tail that mimics mRNA from the host providing genome stability (Figure 1). Picornaviruses possess four capsid proteins having b-barrel folding and code for a polyprotein that is processed by virus-encoded cysteine proteinases; their replication is performed by an RNA-dependent RNA polymerase containing the YGDD sequence motif. Picornaviruses are transmitted through the oral-fecal or aerial routes and many of them affect humans and animals; causing subclinical infections, mild febrile illness, and mild diseases in the gastrointestinal or respiratory tracts; as well as severe heart, liver, and central nervous system diseases. Picornaviruses of the genera Cardiovirus, Cosavirus, Enterovirus, Hepatovirus, Kobuvirus, Parechovirus, and Salivirus infect humans [2].