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MBio Jul 2019The filoviruses are etiological agents of life-threatening hemorrhagic fever with high mortality rate and risk of potential outbreak. Among members of this family, the...
The filoviruses are etiological agents of life-threatening hemorrhagic fever with high mortality rate and risk of potential outbreak. Among members of this family, the Ebola (EBOV), Sudan (SUDV), and Marburg (MARV) viruses are considered the most pathogenic for humans. The ebolavirus nucleoprotein (NP) is the most abundant protein in infected cells and is essential for viral transcription and replication; thus, it represents an attractive target for therapeutic intervention. Here, we present the structure of SUDV NP in complex with the amino-terminal portion of the phosphoprotein VP35 at 2.3 Å. This structure captures VP35 chaperoning SUDV NP in a monomeric and RNA-free state. This transient state has been proposed to be key to maintaining a pool of monomeric and RNA-free NPs prior to NP-NP polymerization and encapsidation of the viral RNA genome. This structure also reveals a newly visualized interaction between NP and VP35, a well-defined beta sheet that is not present in previous structures. Affinity binding assays demonstrate that this beta sheet is essential for maintaining the high-affinity interaction between VP35 and a hydrophobic pocket on SUDV NP, and electron microscopy indicates the importance of this binding interaction to the oligomeric state and assembly of NP in human cells. Complementary structure-directed mutagenesis identifies critical residues conserved across the filovirus family that could be targeted by broadly effective antivirals. Outbreaks of the filoviruses can be unpredictable in timing, location, and identity of the causative virus, with each of Ebola virus, Sudan virus, Bundibugyo virus, and Marburg virus reemerging in the last several years to cause human disease with 30 to 90% lethality. The 2014-2016 outbreak in particular, with nearly 30,000 patients, highlighted the ability of these viruses to emerge unexpectedly and spread rapidly. Two ebolavirus outbreaks have emerged this year, yet we still lack FDA-approved drugs with pan-filovirus activity to treat existing and emergent ebolaviruses. For all filoviruses, the interaction between the nucleoprotein and the phosphoprotein is essential for the virus life cycle and is a potential target for therapeutic intervention. In this report, we describe the crystal structure of the SUDV nucleoprotein with the interacting domain of the viral phosphoprotein, and we identify residues critical for high-affinity interaction and for control of the oligomeric state of the nucleoprotein. Structural comparison of this heterodimer with other members of the filovirus family allowed us to find conserved and essential atomic features that will facilitate understanding of the virus life cycle and the rational design of antivirals.
Topics: Crystallography, X-Ray; Ebolavirus; Filoviridae; Nucleoproteins; Phosphoproteins; Protein Conformation, beta-Strand; Protein Interaction Domains and Motifs; Viral Regulatory and Accessory Proteins
PubMed: 31337716
DOI: 10.1128/mBio.00734-19 -
Viruses Dec 2012Detailed knowledge of the host-virus interactions that accompany filovirus entry into cells is expected to identify determinants of viral virulence and host range, and... (Review)
Review
Detailed knowledge of the host-virus interactions that accompany filovirus entry into cells is expected to identify determinants of viral virulence and host range, and to yield targets for the development of antiviral therapeutics. While it is generally agreed that filovirus entry into the host cytoplasm requires viral internalization into acidic endosomal compartments and proteolytic cleavage of the envelope glycoprotein by endo/lysosomal cysteine proteases, our understanding of the specific endocytic pathways co-opted by filoviruses remains limited. This review addresses the current knowledge on cellular endocytic pathways implicated in filovirus entry, highlights the consensus as well as controversies, and discusses important remaining questions.
Topics: Animals; Endocytosis; Filoviridae; Host Specificity; Host-Pathogen Interactions; Humans; Virulence Factors; Virus Internalization
PubMed: 23342373
DOI: 10.3390/v4123647 -
PLoS Neglected Tropical Diseases Feb 2016The 2013-15 Ebola outbreak was unprecedented due to sustained transmission within urban environments and thousands of survivors. In 2014 the World Health Organization... (Review)
Review
BACKGROUND
The 2013-15 Ebola outbreak was unprecedented due to sustained transmission within urban environments and thousands of survivors. In 2014 the World Health Organization stated that there was insufficient evidence to give definitive guidance about which body fluids are infectious and when they pose a risk to humans. We report a rapid systematic review of published evidence on the presence of filoviruses in body fluids of infected people and survivors.
METHODS
Scientific articles were screened for information about filovirus in human body fluids. The aim was to find primary data that suggested high likelihood of actively infectious filovirus in human body fluids (viral RNA). Eligible infections were from Marburg virus (MARV or RAVV) and Zaire, Sudan, Taï Forest and Bundibugyo species of Ebola. Cause of infection had to be laboratory confirmed (in practice either tissue culture or RT-PCR tests), or evidenced by compatible clinical history with subsequent positivity for filovirus antibodies or inflammatory factors. Data were extracted and summarized narratively.
RESULTS
6831 unique articles were found, and after screening, 33 studies were eligible. For most body fluid types there were insufficient patients to draw strong conclusions, and prevalence of positivity was highly variable. Body fluids taken >16 days after onset were usually negative. In the six studies that used both assay methods RT-PCR tests for filovirus RNA gave positive results about 4 times more often than tissue culture.
CONCLUSIONS
Filovirus was reported in most types of body fluid, but not in every sample from every otherwise confirmed patient. Apart from semen, most non-blood, RT-PCR positive samples are likely to be culture negative and so possibly of low infectious risk. Nevertheless, it is not apparent how relatively infectious many body fluids are during or after illness, even when culture-positive, not least because most test results come from more severe cases. Contact with blood and blood-stained body fluids remains the major risk for disease transmission because of the known high viral loads in blood.
Topics: Animals; Body Fluids; Ebolavirus; Hemorrhagic Fever, Ebola; Humans; Marburg Virus Disease; Marburgvirus; Survivors
PubMed: 26927697
DOI: 10.1371/journal.pntd.0004475 -
Viruses May 2022is a viral family within the order of ; they are negative single-strand RNA viruses that can cause significant diseases in both humans and animals. In order to... (Review)
Review
is a viral family within the order of ; they are negative single-strand RNA viruses that can cause significant diseases in both humans and animals. In order to replicate, paramyxoviruses-as any other viruses-have to bypass an important protective mechanism developed by the host's cells: the defensive line driven by interferon. Once the viruses are recognized, the cells start the production of type I and type III interferons, which leads to the activation of hundreds of genes, many of which encode proteins with the specific function to reduce viral replication. Type II interferon is produced by active immune cells through a different signaling pathway, and activates a diverse range of genes with the same objective to block viral replication. As a result of this selective pressure, viruses have evolved different strategies to avoid the defensive function of interferons. The strategies employed by the different viral species to fight the interferon system include a number of sophisticated mechanisms. Here we analyzed the current status of the various strategies used by paramyxoviruses to subvert type I, II, and III interferon responses.
Topics: Animals; Antiviral Agents; Interferon-gamma; Interferons; Paramyxoviridae; Paramyxovirinae; RNA Viruses; Virus Replication
PubMed: 35632848
DOI: 10.3390/v14051107 -
The Journal of Infectious Diseases Nov 2023The family Filoviridae consists of several virus members known to cause significant mortality and disease in humans. Among these, Ebola virus (EBOV), Marburg virus...
BACKGROUND
The family Filoviridae consists of several virus members known to cause significant mortality and disease in humans. Among these, Ebola virus (EBOV), Marburg virus (MARV), Sudan virus (SUDV), and Bundibugyo virus (BDBV) are considered the deadliest. The vaccine, Ervebo, was shown to rapidly protect humans against Ebola disease, but is indicated only for EBOV infections with limited cross-protection against other filoviruses. Whether multivalent formulations of similar recombinant vesicular stomatitis virus (rVSV)-based vaccines could likewise confer rapid protection is unclear.
METHODS
Here, we tested the ability of an attenuated, quadrivalent panfilovirus VesiculoVax vaccine (rVSV-Filo) to elicit fast-acting protection against MARV, EBOV, SUDV, and BDBV. Groups of cynomolgus monkeys were vaccinated 7 days before exposure to each of the 4 viral pathogens. All subjects (100%) immunized 1 week earlier survived MARV, SUDV, and BDBV challenge; 80% survived EBOV challenge. Survival correlated with lower viral load, higher glycoprotein-specific immunoglobulin G titers, and the expression of B-cell-, cytotoxic cell-, and antigen presentation-associated transcripts.
CONCLUSIONS
These results demonstrate multivalent VesiculoVax vaccines are suitable for filovirus outbreak management. The highly attenuated nature of the rVSV-Filo vaccine may be preferable to the Ervebo "delta G" platform, which induced adverse events in a subset of recipients.
Topics: Humans; Animals; Ebolavirus; Hemorrhagic Fever, Ebola; Marburgvirus; Vaccines, Attenuated; Macaca fascicularis; Viral Vaccines; Vesiculovirus; Vesicular stomatitis Indiana virus; Antibodies, Viral; Ebola Vaccines
PubMed: 37171813
DOI: 10.1093/infdis/jiad157 -
Nature Nov 2017Ebola and Marburg viruses are filoviruses: filamentous, enveloped viruses that cause haemorrhagic fever. Filoviruses are within the order Mononegavirales, which also...
Ebola and Marburg viruses are filoviruses: filamentous, enveloped viruses that cause haemorrhagic fever. Filoviruses are within the order Mononegavirales, which also includes rabies virus, measles virus, and respiratory syncytial virus. Mononegaviruses have non-segmented, single-stranded negative-sense RNA genomes that are encapsidated by nucleoprotein and other viral proteins to form a helical nucleocapsid. The nucleocapsid acts as a scaffold for virus assembly and as a template for genome transcription and replication. Insights into nucleoprotein-nucleoprotein interactions have been derived from structural studies of oligomerized, RNA-encapsidating nucleoprotein, and cryo-electron microscopy of nucleocapsid or nucleocapsid-like structures. There have been no high-resolution reconstructions of complete mononegavirus nucleocapsids. Here we apply cryo-electron tomography and subtomogram averaging to determine the structure of Ebola virus nucleocapsid within intact viruses and recombinant nucleocapsid-like assemblies. These structures reveal the identity and arrangement of the nucleocapsid components, and suggest that the formation of an extended α-helix from the disordered carboxy-terminal region of nucleoprotein-core links nucleoprotein oligomerization, nucleocapsid condensation, RNA encapsidation, and accessory protein recruitment.
Topics: Animals; Chlorocebus aethiops; Cryoelectron Microscopy; Ebolavirus; Electron Microscope Tomography; HEK293 Cells; Humans; Marburgvirus; Models, Molecular; Molecular Conformation; Nucleocapsid; Nucleocapsid Proteins; RNA, Viral; Vero Cells
PubMed: 29144446
DOI: 10.1038/nature24490 -
Viruses Feb 2023RNA viruses are known to induce a wide variety of respiratory tract illnesses, from simple colds to the latest coronavirus pandemic, causing effects on public health and... (Review)
Review
RNA viruses are known to induce a wide variety of respiratory tract illnesses, from simple colds to the latest coronavirus pandemic, causing effects on public health and the economy worldwide. Influenza virus (IV), parainfluenza virus (PIV), metapneumovirus (MPV), respiratory syncytial virus (RSV), rhinovirus (RhV), and coronavirus (CoV) are some of the most notable RNA viruses. Despite efforts, due to the high mutation rate, there are still no effective and scalable treatments that accompany the rapid emergence of new diseases associated with respiratory RNA viruses. Host-directed therapies have been applied to combat RNA virus infections by interfering with host cell factors that enhance the ability of immune cells to respond against those pathogens. The reprogramming of immune cell metabolism has recently emerged as a central mechanism in orchestrated immunity against respiratory viruses. Therefore, understanding the metabolic signature of immune cells during virus infection may be a promising tool for developing host-directed therapies. In this review, we revisit recent findings on the immunometabolic modulation in response to infection and discuss how these metabolic pathways may be used as targets for new therapies to combat illnesses caused by respiratory RNA viruses.
Topics: Humans; Coronavirus; Coronavirus Infections; Enterovirus Infections; Metapneumovirus; RNA; Respiratory Syncytial Virus, Human
PubMed: 36851739
DOI: 10.3390/v15020525 -
Archives of Virology Apr 2019In October 2018, the order Mononegavirales was amended by the establishment of three new families and three new genera, abolishment of two genera, and creation of 28...
In October 2018, the order Mononegavirales was amended by the establishment of three new families and three new genera, abolishment of two genera, and creation of 28 novel species. This article presents the updated taxonomy of the order Mononegavirales as now accepted by the International Committee on Taxonomy of Viruses (ICTV).
Topics: Mononegavirales; Phylogeny; Virology
PubMed: 30663023
DOI: 10.1007/s00705-018-04126-4 -
Proceedings of the National Academy of... May 2022The polymerase complex of nonsegmented negative-strand RNA viruses primarily consists of a large (L) protein and a phosphoprotein (P). L is a multifunctional enzyme...
The polymerase complex of nonsegmented negative-strand RNA viruses primarily consists of a large (L) protein and a phosphoprotein (P). L is a multifunctional enzyme carrying out RNA-dependent RNA polymerization and all other steps associated with transcription and replication, while P is the nonenzymatic cofactor, regulating the function and conformation of L. The structure of a purified vesicular stomatitis virus (VSV) polymerase complex containing L and associated P segments has been determined; however, the location and manner of the attachments of L and P within each virion are unknown, limiting our mechanistic understanding of VSV RNA replication and transcription and hindering engineering efforts of this widely used anticancer and vaccine vector. Here, we have used cryo-electron tomography to visualize the VSV virion, revealing the attachment of the ring-shaped L molecules to VSV nucleocapsid proteins (N) throughout the cavity of the bullet-shaped nucleocapsid. Subtomogram averaging and three-dimensional classification of regions containing N and the matrix protein (M) have yielded the in situ structure of the polymerase complex. On average, ∼55 polymerase complexes are packaged in each virion. The capping domain of L interacts with two neighboring N molecules through flexible attachments. P, which exists as a dimer, bridges separate N molecules and the connector and C-terminal domains of L. Our data provide the structural basis for recruitment of L to N by P in virus assembly and for flexible attachments between L and N, which allow a quick response of L in primary transcription upon cell entry.
Topics: Animals; RNA Viruses; RNA-Dependent RNA Polymerase; Vesicular Stomatitis; Vesicular stomatitis Indiana virus; Vesiculovirus; Virion
PubMed: 35476516
DOI: 10.1073/pnas.2111948119 -
Journal of Virology Mar 2020Southern China is a hot spot of emerging infectious diseases, in which diverse species of bats dwell, a large group of flying mammals considered natural reservoirs for...
Southern China is a hot spot of emerging infectious diseases, in which diverse species of bats dwell, a large group of flying mammals considered natural reservoirs for zoonotic viruses. Recently, divergent filoviruses (FiVs) have been identified in bats within this region, which pose a potential risk to public health, but the true infection situation in bats remains largely unclear. Here, 689 archived bat serum samples were analyzed by enzyme-linked immunosorbent assay (ELISA), Western blotting, and neutralization assay to investigate the seroprevalence and cross-reactivity of four divergent FiVs and two other viruses (rabies virus and Tuhoko pararubulavirus 1) of different families within the order Results showed no cross-antigenicity between FiVs and other mononegaviruses but different cross-reactivity among the FiVs themselves. The total FiV seroreactive rate was 36.3% (250/689), with infection by the indigenous Chinese FiV DH04 or an antigenically related one being the most widely and the most highly prevalent. Further viral metagenomic analysis of fruit bat tissues also identified the gene sequence of a novel FiV. These results indicate the likely prevalence of other so far unidentified FiVs within the Chinese bat population, with frugivorous and bats and insectivorous and bats being their major reservoirs. Bats are natural hosts of many FiVs, from which diverse FiVs were serologically or virologically detected in Africa, Europe, and East Asia. Recently, very divergent FiVs were identified in the Chinese bat population, but their antigenic relationship with other known FiVs remains unknown. Here, we conducted serological characterization and investigation of Chinese indigenous FiVs and prototypes of other viruses in bats. Results indicated that Chinese indigenous FiVs are antigenically distant to other FiVs, and infection of novel or multiple FiVs occurred in Chinese bats, with FiV DH04 or an antigenically related one being the most widely and the most highly prevalent. Additionally, besides and bats, the insectivorous and bats are highly preferential hosts of FiVs. Seroreactive and viral metagenomic results indicated that more as yet unknown bat-borne FiVs circulate in Southern China, and to uncover them further, investigation and timely surveillance is needed.
Topics: Animals; Antibodies, Viral; China; Chiroptera; Coinfection; Disease Reservoirs; Enzyme-Linked Immunosorbent Assay; Filoviridae; Filoviridae Infections; Metagenomics; Neutralization Tests; Paramyxoviridae; Paramyxoviridae Infections; Phylogeny; Rhabdoviridae; Rhabdoviridae Infections; Seroepidemiologic Studies
PubMed: 31941778
DOI: 10.1128/JVI.02042-19