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Journal of Virology Oct 2023Chronic hepatitis B is the most important cause of liver cancer worldwide and affects more than 290 million people. Current treatments are mostly suppressive and rarely...
Chronic hepatitis B is the most important cause of liver cancer worldwide and affects more than 290 million people. Current treatments are mostly suppressive and rarely lead to a cure. Therefore, there is a need for novel and curative drugs that target the host or the causative agent, hepatitis B virus itself. Capsid assembly modulators are an interesting class of antiviral molecules that may one day become part of curative treatment regimens for chronic hepatitis B. Here we explore the characteristics of a particularly interesting subclass of capsid assembly modulators. These so-called non-HAP CAM-As have intriguing properties in cell culture but also clear virus-infected cells from the mouse liver in a gradual and sustained way. We believe they represent a considerable improvement over previously reported molecules and may one day be part of curative treatment combinations for chronic hepatitis B.
Topics: Animals; Humans; Mice; Antiviral Agents; Capsid; Capsid Proteins; Cells, Cultured; Hepatitis B virus; Hepatitis B, Chronic; In Vitro Techniques; Virus Assembly; Disease Models, Animal
PubMed: 37754761
DOI: 10.1128/jvi.00722-23 -
BioRxiv : the Preprint Server For... Sep 2023Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a lipid-enveloped virus that acquires its lipid bilayer from the host cell it infects. SARS-CoV-2 can...
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a lipid-enveloped virus that acquires its lipid bilayer from the host cell it infects. SARS-CoV-2 can spread from cell to cell or from patient to patient by undergoing assembly and budding to form new virions. The assembly and budding of SARS-CoV-2 is mediated by several structural proteins known as envelope (E), membrane (M), nucleoprotein (N) and spike (S), which can form virus-like particles (VLPs) when co-expressed in mammalian cells. Assembly and budding of SARS-CoV-2 from the host ER-Golgi intermediate compartment is a critical step in the virus acquiring its lipid bilayer. To date, little information is available on how SARS-CoV-2 assembles and forms new viral particles from host membranes. In this study, we find the N protein can strongly associate with anionic lipids including phosphoinositides and phosphatidylserine. Moreover, lipid binding is shown to occur in the N protein C-terminal domain, which is supported by extensive analysis. Anionic lipid binding occurs for both the free and N oligomeric forms suggesting N can associate with membranes in the nucleocapsid form. Herein we present a lipid-dependent model based on , cellular and data for the recruitment of N to M assembly sites in the lifecycle of SARS-CoV-2.
PubMed: 37745364
DOI: 10.1101/2023.09.15.557899 -
Infection and Drug Resistance 2023Heterologous virus-like particle (VLP) assembly involving influenza or the Newcastle disease virus matrix protein (M) has been extensively used to explore the efficacies...
PURPOSE
Heterologous virus-like particle (VLP) assembly involving influenza or the Newcastle disease virus matrix protein (M) has been extensively used to explore the efficacies of VLP vaccines against the respiratory syncytial virus (RSV). Here, we attempted to generate homologous RSV VLPs by expressing the pre-fusion (pre-F) or the glycoprotein (G) on the RSV M protein and evaluated their protective efficacy in mice.
METHODS
We generated VLPs using the baculovirus expression system in (Sf9) insect cells. Recombinant baculoviruses expressing the RSV pre-F, G, and M antigens were inoculated into Sf9 cells, and particles were self-assembled. Mice were immunized with either pre-F or G-expressing VLPs, and immune parameters were assessed to determine protection.
RESULTS
Our findings show that successful VLP assembly can be achieved by utilizing recombinant baculoviruses expressing the RSV pre-F or G proteins with the native matrix protein. Mice immunized with either pre-F or the G antigen-expressing VLPs elicited robust serum-mediated virus neutralization. VLP immunization evoked Th1-biased RSV-specific antibody responses in the sera of mice. Following challenge infection with the RSV A2 strain, immunized mice experienced lesser eosinophil and IL-4 accumulation in the lungs, though a substantial increase in TNF-α secretion was observed from CD4+ T cells. Interestingly, splenic antibody-secreting cell responses were substantially enhanced against RSV F antigen, but not against the RSV G antigen following immunization and challenge infection. Immunizing mice with the VLPs significantly inhibited pulmonary histopathology development, as indicated by the diminished inflammatory immune cell influx and mucin secretion.
CONCLUSION
Combined, these vaccine-induced immune responses contributed to successfully inhibiting the RSV replication in the lungs of mice and demonstrated that RSV VLP assembly using insect cell-derived homologous RSV matrix protein is a feasible approach.
PubMed: 37719656
DOI: 10.2147/IDR.S426039 -
Viruses Sep 2023Positive-sense single-stranded RNA (ssRNA) bacteriophages (phages) were first isolated six decades ago. Since then, extensive research has been conducted on these ssRNA... (Review)
Review
Positive-sense single-stranded RNA (ssRNA) bacteriophages (phages) were first isolated six decades ago. Since then, extensive research has been conducted on these ssRNA phages, particularly those infecting . With small genomes of typically 3-4 kb that usually encode four essential proteins, ssRNA phages employ a straightforward infectious cycle involving host adsorption, genome entry, genome replication, phage assembly, and host lysis. Recent advancements in metagenomics and transcriptomics have led to the identification of ~65,000 sequences from ssRNA phages, expanding our understanding of their prevalence and potential hosts. This review article illuminates significant investigations into ssRNA phages, with a focal point on their structural aspects, providing insights into the various stages of their infectious cycle.
Topics: Bacteriophages; Escherichia coli; RNA, Viral; Virus Assembly; RNA Phages; Genome, Viral
PubMed: 37896763
DOI: 10.3390/v15101985 -
Nucleus (Austin, Tex.) Dec 2024Paraspeckles are non-membranous subnuclear bodies, formed through the interaction between the architectural long non-coding RNA (lncRNA) nuclear paraspeckle assembly... (Review)
Review
Paraspeckles are non-membranous subnuclear bodies, formed through the interaction between the architectural long non-coding RNA (lncRNA) nuclear paraspeckle assembly transcript 1 (NEAT1) and specific RNA-binding proteins, including the three (DBHS) family members (PSPC1 (Paraspeckle Component 1), SFPQ (Splicing Factor Proline and Glutamine Rich) and NONO (Non-POU domain-containing octamer-binding protein)). Paraspeckle components were found to impact viral infections through various mechanisms, such as induction of antiviral gene expression, IRES-mediated translation, or viral mRNA polyadenylation. A complex involving NEAT1 RNA and paraspeckle proteins was also found to modulate interferon gene transcription after nuclear DNA sensing, through the activation of the cGAS-STING axis. This review aims to provide an overview on how these elements actively contribute to the dynamics of viral infections.
Topics: Humans; Virus Diseases; Animals; RNA, Long Noncoding; RNA-Binding Proteins
PubMed: 38717150
DOI: 10.1080/19491034.2024.2350178 -
Nature Microbiology Jun 2024Ebola virus and other orthoebolaviruses cause severe haemorrhagic fevers in humans, with very high case fatality rates. Their non-segmented single-stranded RNA genome... (Review)
Review
Ebola virus and other orthoebolaviruses cause severe haemorrhagic fevers in humans, with very high case fatality rates. Their non-segmented single-stranded RNA genome encodes only seven structural proteins and a small number of non-structural proteins to facilitate the virus life cycle. The basics of this life cycle are well established, but recent advances have substantially increased our understanding of its molecular details, including the viral and host factors involved. Here we provide a comprehensive overview of our current knowledge of the molecular details of the orthoebolavirus life cycle, with a special focus on proviral host factors. We discuss the multistep entry process, viral RNA synthesis in specialized phase-separated intracellular compartments called inclusion bodies, the expression of viral proteins and ultimately the assembly of new virus particles and their release at the cell surface. In doing so, we integrate recent studies into the increasingly detailed model that has developed for these fundamental aspects of orthoebolavirus biology.
Topics: Ebolavirus; Humans; Hemorrhagic Fever, Ebola; RNA, Viral; Virus Replication; Viral Proteins; Virus Assembly; Virus Internalization; Genome, Viral; Animals; Virion; Host-Pathogen Interactions
PubMed: 38783022
DOI: 10.1038/s41564-024-01703-z -
PLoS Pathogens Jul 2023Liver-generated plasma Apolipoprotein E (ApoE)-containing lipoproteins (LPs) (ApoE-LPs) play central roles in lipid transport and metabolism. Perturbations of ApoE can...
Liver-generated plasma Apolipoprotein E (ApoE)-containing lipoproteins (LPs) (ApoE-LPs) play central roles in lipid transport and metabolism. Perturbations of ApoE can result in several metabolic disorders and ApoE genotypes have been associated with multiple diseases. ApoE is synthesized at the endoplasmic reticulum and transported to the Golgi apparatus for LP assembly; however, the ApoE-LPs transport pathway from there to the plasma membrane is largely unknown. Here, we established an integrative imaging approach based on a fully functional fluorescently tagged ApoE. We found that newly synthesized ApoE-LPs accumulate in CD63-positive endosomes of hepatocytes. In addition, we observed the co-egress of ApoE-LPs and CD63-positive intraluminal vesicles (ILVs), which are precursors of extracellular vesicles (EVs), along the late endosomal trafficking route in a microtubule-dependent manner. A fraction of ApoE-LPs associated with CD63-positive EVs appears to be co-transmitted from cell to cell. Given the important role of ApoE in viral infections, we employed as well-studied model the hepatitis C virus (HCV) and found that the viral replicase component nonstructural protein 5A (NS5A) is enriched in ApoE-containing ILVs. Interaction between NS5A and ApoE is required for the efficient release of ILVs containing HCV RNA. These vesicles are transported along the endosomal ApoE egress pathway. Taken together, our data argue for endosomal egress and transmission of hepatic ApoE-LPs, a pathway that is hijacked by HCV. Given the more general role of EV-mediated cell-to-cell communication, these insights provide new starting points for research into the pathophysiology of ApoE-related metabolic and infection-related disorders.
Topics: Humans; Hepacivirus; Lipopolysaccharides; Virus Assembly; Hepatitis C; Endosomes; Apolipoproteins E
PubMed: 37506130
DOI: 10.1371/journal.ppat.1011052 -
Nature Communications Jul 2023Great effort has been devoted to discovering the basis of A3G-Vif interaction, the key event of HIV's counteraction mechanism to evade antiviral innate immune response....
Great effort has been devoted to discovering the basis of A3G-Vif interaction, the key event of HIV's counteraction mechanism to evade antiviral innate immune response. Here we show reconstitution of the A3G-Vif complex and subsequent A3G ubiquitination in vitro and report the cryo-EM structure of the A3G-Vif complex at 2.8 Å resolution using solubility-enhanced variants of A3G and Vif. We present an atomic model of the A3G-Vif interface, which assembles via known amino acid determinants. This assembly is not achieved by protein-protein interaction alone, but also involves RNA. The cryo-EM structure and in vitro ubiquitination assays identify an adenine/guanine base preference for the interaction and a unique Vif-ribose contact. This establishes the biological significance of an RNA ligand. Further assessment of interactions between A3G, Vif, and RNA ligands show that the A3G-Vif assembly and subsequent ubiquitination can be controlled by amino acid mutations at the interface or by polynucleotide modification, suggesting that a specific chemical moiety would be a promising pharmacophore to inhibit the A3G-Vif interaction.
Topics: vif Gene Products, Human Immunodeficiency Virus; HIV-1; RNA; Antiviral Agents; Amino Acids; APOBEC-3G Deaminase; Cytidine Deaminase
PubMed: 37419875
DOI: 10.1038/s41467-023-39796-5 -
Chemical Society Reviews Jul 2024Nucleic acid aptamers are oligonucleotide chains with molecular recognition properties. Compared with antibodies, aptamers show advantages given that they are readily... (Review)
Review
Nucleic acid aptamers are oligonucleotide chains with molecular recognition properties. Compared with antibodies, aptamers show advantages given that they are readily produced chemical synthesis and elicit minimal immunogenicity in biomedicine applications. Notably, aptamer-encoded nucleic acid assemblies further improve the binding affinity of aptamers with the targets due to their multivalent synergistic interactions. Specially, aptamers can be engineered with special topological arrangements in nucleic acid assemblies, which demonstrate spatial and valence matching towards antigens on viruses, thus showing potential in the detection and therapeutic applications of viruses. This review presents the recent progress on the aptamers explored for SARS-CoV-2 detection and infection treatment, wherein applications of aptamer-based assembly systems are introduced in detail. Screening methods and chemical modification strategies for aptamers are comprehensively summarized, and the types of aptamers employed against different target domains of SARS-CoV-2 are illustrated. The evolution of aptamer-based assembly systems for the detection and neutralization of SARS-CoV-2, as well as the construction principle and characteristics of aptamer-based DNA assemblies are demonstrated. The typically representative works are presented to demonstrate how to assemble aptamers rationally and elaborately for specific applications in SARS-CoV-2 diagnosis and neutralization. Finally, we provide deep insights into the current challenges and future perspectives towards aptamer-based nucleic acid assemblies for virus detection and neutralization in nanomedicine.
Topics: Aptamers, Nucleotide; SARS-CoV-2; Humans; COVID-19; COVID-19 Drug Treatment; Antiviral Agents
PubMed: 38829187
DOI: 10.1039/d3cs00774j -
Viruses Oct 2023Herpesviruses are enveloped and have an amorphous protein layer surrounding the capsid, which is termed the tegument. Tegument proteins perform critical functions... (Review)
Review
Herpesviruses are enveloped and have an amorphous protein layer surrounding the capsid, which is termed the tegument. Tegument proteins perform critical functions throughout the viral life cycle. This review provides a comprehensive and comparative analysis of the roles of specific tegument proteins in capsid transport and virion morphogenesis of selected, well-studied prototypes of each of the three subfamilies of i.e., human herpesvirus-1/herpes simplex virus-1 (), human herpesvirus-5/cytomegalovirus () and human herpesvirus -8/Kaposi's sarcomavirus (). Most of the current knowledge is based on alpha herpesviruses, in particular HSV-1. While some tegument proteins are released into the cytoplasm after virus entry, several tegument proteins remain associated with the capsid and are responsible for transport to and docking at the nucleus. After replication and capsid formation, the capsid is enveloped at the nuclear membrane, which is referred to as primary envelopment, followed by de-envelopment and release into the cytoplasm. This requires involvement of at least three tegument proteins. Subsequently, multiple interactions between tegument proteins and capsid proteins, other tegument proteins and glycoproteins are required for assembly of the virus particles and envelopment at the Golgi, with certain tegument proteins acting as the central hub for these interactions. Some redundancy in these interactions ensures appropriate morphogenesis.
Topics: Humans; Capsid Proteins; Capsid; Virus Assembly; Herpesviridae; Herpesvirus 1, Human; Herpesvirus 8, Human; Morphogenesis; Virion; Viral Structural Proteins
PubMed: 37896835
DOI: 10.3390/v15102058