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Viruses Sep 2021The cellular metabolism of host tRNAs and life cycle of HIV-1 cross paths at several key virus-host interfaces. Emerging data suggest a multi-faceted interplay between... (Review)
Review
The cellular metabolism of host tRNAs and life cycle of HIV-1 cross paths at several key virus-host interfaces. Emerging data suggest a multi-faceted interplay between host tRNAs and HIV-1 that plays essential roles, both structural and regulatory, in viral genome replication, genome packaging, and virion biogenesis. HIV-1 not only hijacks host tRNAs and transforms them into obligatory reverse transcription primers but further commandeers tRNAs to regulate the localization of its major structural protein, Gag, via a specific interface. This review highlights recent advances in understanding tRNA-HIV-1 interactions, primarily from a structural perspective, which start to elucidate their underlying molecular mechanisms, intrinsic specificities, and biological significances. Such understanding may provide new avenues toward developing HIV/AIDS treatments and therapeutics including small molecules and RNA biologics that target these host-virus interfaces.
Topics: HIV Seropositivity; HIV-1; Host Microbial Interactions; Humans; RNA, Transfer; RNA, Viral; Virus Assembly; Virus Replication; gag Gene Products, Human Immunodeficiency Virus
PubMed: 34578400
DOI: 10.3390/v13091819 -
PLoS Pathogens Aug 2022Human Cytomegalovirus (HCMV) can infect a variety of cell types by using virions of varying glycoprotein compositions. It is still unclear how this diversity is...
Human Cytomegalovirus (HCMV) can infect a variety of cell types by using virions of varying glycoprotein compositions. It is still unclear how this diversity is generated, but spatio-temporally separated envelopment and egress pathways might play a role. So far, one egress pathway has been described in which HCMV particles are individually enveloped into small vesicles and are subsequently exocytosed continuously. However, some studies have also found enveloped virus particles inside multivesicular structures but could not link them to productive egress or degradation pathways. We used a novel 3D-CLEM workflow allowing us to investigate these structures in HCMV morphogenesis and egress at high spatio-temporal resolution. We found that multiple envelopment events occurred at individual vesicles leading to multiviral bodies (MViBs), which subsequently traversed the cytoplasm to release virions as intermittent bulk pulses at the plasma membrane to form extracellular virus accumulations (EVAs). Our data support the existence of a novel bona fide HCMV egress pathway, which opens the gate to evaluate divergent egress pathways in generating virion diversity.
Topics: Cytomegalovirus; Cytoplasm; Humans; Virion; Virus Assembly
PubMed: 35925870
DOI: 10.1371/journal.ppat.1010575 -
Viruses Jan 2022The hepatitis C virus (HCV) co-opts numerous cellular elements, including proteins, lipids, and microRNAs, to complete its viral life cycle. The cellular RNA-binding...
The hepatitis C virus (HCV) co-opts numerous cellular elements, including proteins, lipids, and microRNAs, to complete its viral life cycle. The cellular RNA-binding protein, poly(rC)-binding protein 1 (PCBP1), was previously reported to bind to the 5' untranslated region (UTR) of the HCV genome; however, its importance in the viral life cycle has remained unclear. Herein, we sought to clarify the role of PCBP1 in the HCV life cycle. Using the HCV cell culture (HCVcc) system, we found that knockdown of endogenous PCBP1 resulted in an overall decrease in viral RNA accumulation, yet resulted in an increase in extracellular viral titers. To dissect PCBP1's specific role in the HCV life cycle, we carried out assays for viral entry, translation, genome stability, RNA replication, as well as virion assembly and secretion. We found that PCBP1 knockdown did not directly affect viral entry, translation, RNA stability, or RNA replication, but resulted in an overall increase in infectious particle secretion. This increase in virion secretion was evident even when viral RNA synthesis was inhibited, and blocking virus secretion could partially restore the viral RNA accumulation decreased by PCBP1 knockdown. We therefore propose a model where endogenous PCBP1 normally limits virion assembly and secretion, which increases viral RNA accumulation in infected cells by preventing the departure of viral genomes packaged into virions. Overall, our findings improve our understanding of how cellular RNA-binding proteins influence viral genomic RNA utilization during the HCV life cycle.
Topics: Cell Line; DNA-Binding Proteins; Hepacivirus; Humans; RNA, Viral; RNA-Binding Proteins; Viral Genome Packaging; Virion; Virus Assembly
PubMed: 35215884
DOI: 10.3390/v14020291 -
Viruses Jan 2022Several strategies have been developed to fight viral infections, not only in humans but also in animals and plants. Some of them are based on the development of... (Review)
Review
Several strategies have been developed to fight viral infections, not only in humans but also in animals and plants. Some of them are based on the development of efficient vaccines, to target the virus by developed antibodies, others focus on finding antiviral compounds with activities that inhibit selected virus replication steps. Currently, there is an increasing number of antiviral drugs on the market; however, some have unpleasant side effects, are toxic to cells, or the viruses quickly develop resistance to them. As the current situation shows, the combination of multiple antiviral strategies or the combination of the use of various compounds within one strategy is very important. The most desirable are combinations of drugs that inhibit different steps in the virus life cycle. This is an important issue especially for RNA viruses, which replicate their genomes using error-prone RNA polymerases and rapidly develop mutants resistant to applied antiviral compounds. Here, we focus on compounds targeting viral structural capsid proteins, thereby inhibiting virus assembly or disassembly, virus binding to cellular receptors, or acting by inhibiting other virus replication mechanisms. This review is an update of existing papers on a similar topic, by focusing on the most recent advances in the rapidly evolving research of compounds targeting capsid proteins of RNA viruses.
Topics: Antiviral Agents; Capsid Proteins; Humans; RNA Virus Infections; RNA Viruses; Virus Assembly; Virus Replication
PubMed: 35215767
DOI: 10.3390/v14020174 -
Bioorganic & Medicinal Chemistry Letters Aug 2023The protein that forms the inner shell of the HBV virus, known as the capsid core protein, plays a crucial role in allowing chronic HBV infections to persist. Studies...
The protein that forms the inner shell of the HBV virus, known as the capsid core protein, plays a crucial role in allowing chronic HBV infections to persist. Studies have shown that disrupting the assembly of the capsid can effectively combat the virus, and small molecule drugs that target the HBV capsid assembly modulator (CAM) process have been successful in clinical trials. Herein is described a distinct series of di-fluoro azepane CAMs with exceptional potency, pharmacokinetic, and solubility properties.
Topics: Capsid; Hepatitis B virus; Virus Assembly; Antiviral Agents; Capsid Proteins; Virus Replication
PubMed: 37247697
DOI: 10.1016/j.bmcl.2023.129350 -
Journal of Virology May 2019Tailed double-stranded DNA (dsDNA) bacteriophages, herpesviruses, and adenoviruses package their genetic material into a precursor capsid through a dodecameric ring...
Tailed double-stranded DNA (dsDNA) bacteriophages, herpesviruses, and adenoviruses package their genetic material into a precursor capsid through a dodecameric ring complex called the portal protein, which is located at a unique 5-fold vertex. In several phages and viruses, including T4, Φ29, and herpes simplex virus 1 (HSV-1), the portal forms a nucleation complex with scaffolding proteins (SPs) to initiate procapsid (PC) assembly, thereby ensuring incorporation of only one portal ring per capsid. However, for bacteriophage P22, the role of its portal protein in initiation of procapsid assembly is unclear. We have developed an P22 assembly assay where portal protein is coassembled into procapsid-like particles (PLPs). Scaffolding protein also catalyzes oligomerization of monomeric portal protein into dodecameric rings, possibly forming a scaffolding protein-portal protein nucleation complex that results in one portal ring per P22 procapsid. Here, we present evidence substantiating that the P22 portal protein, similarly to those of other dsDNA viruses, can act as an assembly nucleator. The presence of the P22 portal protein is shown to increase the rate of particle assembly and contribute to proper morphology of the assembled particles. Our results highlight a key function of portal protein as an assembly initiator, a feature that is likely conserved among these classes of dsDNA viruses. The existence of a single portal ring is essential to the formation of infectious virions in the tailed double-stranded DNA (dsDNA) phages, herpesviruses, and adenoviruses and, as such, is a viable antiviral therapeutic target. How only one portal is selectively incorporated at a unique vertex is unclear. In many dsDNA viruses and phages, the portal protein acts as an assembly nucleator. However, early work on phage P22 assembly indicated that the portal protein did not function as a nucleator for procapsid (PC) assembly, leading to the suggestion that P22 uses a unique mechanism for portal incorporation. Here, we show that portal protein nucleates assembly of P22 procapsid-like particles (PLPs). Addition of portal rings to an assembly reaction increases the rate of formation and yield of particles and corrects improper particle morphology. Our data suggest that procapsid assembly may universally initiate with a nucleation complex composed minimally of portal and scaffolding proteins (SPs).
Topics: Bacteriophage P22; Capsid; Virus Assembly
PubMed: 30787152
DOI: 10.1128/JVI.00187-19 -
Emerging Microbes & Infections Dec 2022Zika virus (ZIKV), a family member in the genus, has re-emerged as a global public health concern. The envelope (E) proteins of flaviviruses play a dual role in viral...
Zika virus (ZIKV), a family member in the genus, has re-emerged as a global public health concern. The envelope (E) proteins of flaviviruses play a dual role in viral assembly and entry. To identify the key residues of E in virus entry, we generated a ZIKV -complemented particle (ZIKV) system, in which a subgenomic reporter replicon was packaged by -complementation with expression of CprME. We performed mutagenesis studies of the loop regions that protrude from the surface of the virion in the E ectodomains (DI, DII, DIII). Most mutated ZIKV exhibited deficient egress. Mutations in DII and in the hinge region of DI and DIII affected prM expression. With a bioorthogonal system, photocrosslinking experiments identified crosslinked intracellular E trimers and demonstrated that egress-deficient mutants in DIII impaired E trimerization. Of these mutants, an E-trimerization-dead mutation D389A that nears the E-E interface between two neighbouring spikes in the immature virion completely abolished viral egress. Several mutations abolished ZIKV' entry, without severely affecting viral egress. Further virus binding experiments demonstrated a deficiency of the mutated ZIKV in virus attachment. Strikingly, synthesized peptide containing residues of two mutants (268-273aa in DII) could bind to host cells and significantly compete for viral attachment and interfere with viral infection, suggesting an important role of these resides in virus entry. Our findings uncovered the requirement for DIII mediated-E trimerization in viral egress, and discovered a key residue group in DII that participates in virus entry.
Topics: Flavivirus; Humans; Viral Envelope Proteins; Virus Assembly; Virus Replication; Zika Virus; Zika Virus Infection
PubMed: 35612559
DOI: 10.1080/22221751.2022.2082888 -
Virologie (Montrouge, France) Feb 2019
Topics: Biomedical Research; CRISPR-Cas Systems; Drug Delivery Systems; Gene Editing; Gene Transfer Techniques; Genetic Vectors; Humans; Nanotechnology; Virion; Virus Assembly
PubMed: 31131829
DOI: 10.1684/vir.2019.0759 -
Advances in Virus Research 2020Potyvirus genus clusters a significant and expanding number of widely distributed plant viruses, responsible for large losses impacting most crops of economic interest.... (Review)
Review
Potyvirus genus clusters a significant and expanding number of widely distributed plant viruses, responsible for large losses impacting most crops of economic interest. The potyviral genome is a single-stranded, linear, positive-sense RNA of around 10kb that is encapsidated in flexuous rod-shaped filaments, mostly made up of a helically arranged coat protein (CP). Beyond its structural role of protecting the viral genome, the potyviral CP is a multitasking protein intervening in practically all steps of the virus life cycle. In particular, interactions between the CP and the viral RNA must be tightly controlled to allow the correct assignment of the RNA to each of its functions through the infection process. This review attempts to bring together the most relevant available information regarding the architecture and modus operandi of potyviral CP and virus particles, highlighting significant discoveries, but also substantial gaps in the existing knowledge on mechanisms orchestrating virion assembly and disassembly. Biotechnological applications based on potyvirus nanoparticles is another important topic addressed here.
Topics: Biotechnology; Books; Capsid Proteins; Genome, Viral; Genomics; Humans; Potyvirus; RNA, Viral; Virion; Virus Assembly; Viruses
PubMed: 33837716
DOI: 10.1016/bs.aivir.2020.09.001 -
Bioorganic & Medicinal Chemistry Letters Sep 2022The HBV capsid core protein serves a number of important functions in the viral life cycle enabling chronic HBV infection to persist, and therefore is a promising drug...
The HBV capsid core protein serves a number of important functions in the viral life cycle enabling chronic HBV infection to persist, and therefore is a promising drug target. Interfering with capsid assembly has shown efficacy in clinical trials with small molecule capsid assembly modulators (CAMs). Herein is described the further optimization of a progressive series of diazepinone HBV CAMs.
Topics: Antiviral Agents; Capsid; Capsid Proteins; Hepatitis B virus; Virus Assembly
PubMed: 35644301
DOI: 10.1016/j.bmcl.2022.128823