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Order Patatavirales
Published in Paul Pumpens, Peter Pushko, Philippe Le Mercier, Virus-Like Particles, 2022
Paul Pumpens, Peter Pushko, Philippe Le Mercier
Figure 29.2 shows the genomic structure of the Potyviridae family members. As summarized by Wylie et al. (2017), the genomes range from 8.2–11.3 kb, with an average size of 9.7 kb. The most genomes are monopartite, but those of members of the genus Bymovirus are bipartite. The genomes have a VPg of about 24 kDa, which is covalently linked to the 5′- end, while the 3′-terminus is polyadenylated. The encoded large polyprotein is self-cleaved into a set of functional proteins, and the gene order is generally conserved throughout the family.
Yellow Fever
Published in Rae-Ellen W. Kavey, Allison B. Kavey, Viral Pandemics, 2020
Rae-Ellen W. Kavey, Allison B. Kavey
The yellow fever virus is now known to be a small (40–60 nm), enveloped virus harboring a single positive-strand RNA genome of 11 kb that like the smallpox virus, replicates in the cytoplasm of infected cells. The genome encodes a polyprotein that is cleaved into three structural proteins and seven non-structural proteins. Surface macromolecules of the YF virus are its main virulence factors and contribute to the entry, signaling and cell–cell interactions of the virus. During virus replication, the structural proteins are incorporated into progeny virions, while the non-structural proteins remain in infected cells where they coordinate RNA replication and viral assembly, and modulate innate immune responses.46 The synthesis of yellow fever virus RNA is detectable within 3–6 hours after infection and progeny virions created in the host cell are released after about 12 hours.
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].
Differential expression of miRNAs in a human developing neuronal cell line chronically infected with Zika virus
Published in Libyan Journal of Medicine, 2021
Omar Bagasra, Narges Sadat Shamabadi, Pratima Pandey, Abdelrahman Desoky, Ewen McLean
ZIKV is a positive sense, single-strand ribonucleic acid (ssRNA) virus with a genome size of approximately 10.8 kilobases [7]. This viral RNA is translated into a single polyprotein of 3423 amino acids in length which encodes 3 structural proteins – capsid (C), envelope (E), and membrane (M). The M is generated from its precursor premembrane (prM). In addition, the ZIKV ssRNA also encodes for seven nonstructural proteins: NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5. The structural proteins play a crucial role in replication and packaging of the viral genome as well as in disrupting the host pathways in favor of the virus. The generation of the 10 individual proteins from the polyprotein is regulated by viral and host proteases, as well by host miRNAs [7]. ZIKV replication occurs on complex virus-induced membrane structures incorporating host and viral factors [7,19,20] where it is believed that the replication process of ZIKV encounters host regulatory factors and the intracellular defense system of the host including miRNAs [13]
Can nanotechnology help in the fight against COVID-19?
Published in Expert Review of Anti-infective Therapy, 2020
Gabriela Palestino, Ileana García-Silva, Omar González-Ortega, Sergio Rosales-Mendoza
Liposome-based vaccines targeting coronaviruses is another approach for nanovaccine development. A liposome vaccine candidate was reported, targeting the non-structural polyprotein 1a (pp1a); with the ability to induce in mice the expansion of IFN-γ-producing CD8 + T cells and in vivo killing activities after s.c. immunization; moreover, the expanded CTLs were able to kill cells expressing naturally processed pp1a-derived peptides [89]. A similar approach was implemented for the N protein peptides, which led to the successful induction of CTLs responses in mice; mediating the in vivo clearance of vaccinia virus expressing epitopes of SARS-CoV [90]. Challenge studies to determine immunoprotection against the coronavirus itself remain as pending objectives. Interestingly, liposome-based complexes have also been applied for immunization aiming to generate monoclonal antibodies against MERS-CoV [91,92]. It is worth mentioning that at least one of the prominent vaccines under development against SARS-CoV-2 is based on liposomes that contain an mRNA encoding for the prefusion stabilized spike protein 2019-nCoV (mRNA-1273). The formulation contains an ionizable lipid, SM-102, and 3 commercially available lipids: cholesterol, DSPC, and PEG2000 DMG [93].
Hand, foot, and mouth disease associated with coxsackievirus A10: more serious than it seems
Published in Expert Review of Anti-infective Therapy, 2019
Lianlian Bian, Fan Gao, Qunying Mao, Shiyang Sun, Xing Wu, Siyuan Liu, Xiaoming Yang, Zhenglun Liang
The prototype strain of CV-A10, Kowalik (GenBank no: AY421767), was isolated in the USA in 1950 [55]. The complete genome of Kowalik is 7409 bp in length and contains a large open reading frame of 6579 bases, that encodes a predicted polyprotein precursor of 2192 amino acids. The polyprotein is processed during and following translation by viral proteases to yield the mature viral polypeptides. The P1 region encodes the capsid proteins VP4, VP2, VP3, and VP1, whereas the P2 and P3 regions encode proteins involved in polyprotein processing, RNA replication and shut-down of host-cell protein synthesis [55,56]. Although CV-A10 has been an emerging pathogen which caused HFMD outbreaks and other diseases worldwide, there has been a lack of research on the characteristics of the molecular epidemiology of CV-A10 and no accepted standard for CV-A10 genome classification is available.