The Viruses
Julius P. Kreier in Infection, Resistance, and Immunity, 2022
Viruses have no intrinsic means to generate energy so they must rely totally on the metabolic machinery of host cells to synthesize new viral components. During viral replication, the nucleic acid of the virus which composes its genome becomes active within the infected cell and serves as a template to make copies of itself and to produce new viral proteins. These newly synthesized proteins and genomic elements assemble into new infectious virions that are released by cell lysis or by budding from the host cell. In some cases the viral genome may incorporate into the host cell DNA leading to persistent infections that may lead to many changes in the host cell including cancer. The genetic information in the virus genome and in the host cell determines the outcome of the virus-cell interaction.
Vaccinia Virus as a Carrier of Vaccine Antigens
F. Y. Liew in Vaccination Strategies of Tropical Diseases, 2017
Poxviruses are unusual DNA viruses in that they replicate in the cytoplasm (for review see Reference 22). This cytoplasmic replication is possible due to the possession of virus-coded enzymes such as DNA and RNA polymerase. The virus has a broad host range and replicates in most mammalian cell lines. Virus replication is divided into early and late phases that are defined as the periods before and after the onset of virus DNA replication. The complete cycle takes from 15 to 20 h during a high-mulitplicity infection and replication occurs in discrete cytoplasmic factories. During virion morphogenesis distinct forms of maturing virus particles are visible by electron microscopy.4 Most infectious virus progeny remains cell associated so that virus is usually purified from cytoplasmic extracts. The amount of extracellular virus varies, depending on the virus strain and cell line,23 but is significant since it contains an additional lipid envelope, derived from the Golgi membrane, that contains several virus glycoproteins. These are absent from intracellular virus and are important in virus pathogenesis.24,25
Write short notes on viral replication
Nathaniel Knox Cartwright, Petros Carvounis in Short Answer Questions for the MRCOphth Part 1, 2018
There are several stages to viral replication: attachment to host cell by random collision, electrostatic attachment or by specific host receptors. This process is called adsorptioncell penetration occurs either by viropexis or by fusion of the viral envelope and the cell membranehost cell enzymes digest the capsidnucleic acid replication occurs (see below)assembly of the newly replicated virion occursa period of maturation followsnewly formed virus particles are released by cell lysis or budding through the cell membrane.
Phosphonate inhibitors of West Nile virus NS2B/NS3 protease
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2019
Marcin Skoreński, Aleksandra Milewska, Krzysztof Pyrć, Marcin Sieńczyk, Józef Oleksyszyn
The flaviviral genome is a positive-sense single strand RNA. The viral replication process occurs in the cytoplasm where the RNA serves as a template for production of a large polyprotein, which is further processed by host and viral proteases. This proteolytic maturation yields structural (C, prM, and E) and non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5). NS3 plays a key role during the polyprotein processing. This protein is composed of an N-terminal protease domain (1–179 amino acids) and a C-terminal helicase domain (residues 180–618). It has been demonstrated that inactivation of NS2B/NS3 protease catalytic centre blocks viral replication8. To become fully functional, the NS3 segment requires a short co-factor, NS2B. The WNV protease contains the classical serine protease catalytic triad Asp-His-Ser. The protease binding site exists as a shallow groove composed of 7 subsites (S4-S3’, according to the Schechter and Berger nomenclature)9. An analysis of the substrate preference of WNV NS2B/NS3 protease revealed that the natural substrates contain a highly conserved arginine residue in the P1 position. Further studies showed that basic amino acids were also preferred in P2 as well as in the P3 positions10,11.
Curcumin and curcumin-loaded nanoparticles: antipathogenic and antiparasitic activities
Published in Expert Review of Anti-infective Therapy, 2020
Mahendra Rai, Avinash P. Ingle, Raksha Pandit, Priti Paralikar, Netravati Anasane, Carolina Alves Dos Santos
Recently, Mathew and Hsu [49] reviewed the antiviral activity of curcumin against different viruses and hypothesized that curcumin inhibits the virus either by interfering in the replication machinery of viruses or by affecting the cellular signaling at the time of viral replication. According to Qin et al. [92], curcumin suppresses the replication of viral RNA, expression of viral proteins, affects the overall production of viral progeny, and also induces the production of reactive oxygen species. Similarly, Moghadamtousi et al. [33] reviewed various antiviral mechanisms for different viruses which mainly include (i) inhibition of hemagglutination (ii) diminution in virus replication (iii) inhibition expression of viral oncoproteins (iv)down-regulation effect on the transcription (v) reduction in production of infective viral particles, etc.
Fatal ReincaRNAtion of VIRUS causing COronaVIrus disease
Published in International Reviews of Immunology, 2022
The development of appropriate therapeutics against viruses is one of the challenging tasks in biomedical sciences. Although some therapeutic agents are available for some viral diseases, such agents are associated with a wide range of side effects because most of the molecules in the agents interfere either with nucleic acid synthesis or metabolic enzymes. Thus, to control virus replication other strategies are needed, such as the activation of innate antiviral responses. The article by Habeichi et al discusses different ways to enhance the innate antiviral immunity of the hose to control COVID virus replication. The articles in this issue will be interesting to a wide range of readers in the fields of immunology, virology, epidemiology, as well as those in almost all fields of biomedical science (Figure 1).
Related Knowledge Centers
- DNA
- Genome
- Rna
- Virus
- Messenger Rna
- Cell Membrane
- Host
- Transcription
- Cell
- Endocytosis