A #Chimeric #Sudan #VLP #Vaccine Candidate Produced by a Recombinant Baculovirus System Induces Specific Immune Responses in Mice and Horses (Viruses, abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Viruses. 2020 Jan 3;12(1). pii: E64. doi: 10.3390/v12010064.

A Chimeric Sudan Virus-Like Particle Vaccine Candidate Produced by a Recombinant Baculovirus System Induces Specific Immune Responses in Mice and Horses.

Wu F1, Zhang S1,2, Zhang Y1,2, Mo R1,3, Yan F1,4,5, Wang H1,6, Wong G7,8, Chi H1,4,5, Wang T1,4,5, Feng N1,4,5, Gao Y1,4,5, Xia X1,4,5, Zhao Y1,4,5, Yang S1,4,5.

Author information: 1 Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun 130122, China. 2 College of Wildlife Resources, Northeast Forestry University, Harbin 150040, China. 3 Animal Science and Technology College, Jilin Agricultural University, Changchun 130118, China. 4 Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Changchun 130000, China. 5 Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Disease and Zoonoses, Yangzhou 225009, China. 6 College of Veterinary Medicine, Jilin University, Changchun 130062, China. 7 Institute Pasteur of Shanghai, Chinese Academy of Science, Shanghai 20031, China. 8 Special Pathogens Program, Public Health Agency of Canada, Winnipeg, MB R3E3R2, Canada.

 

Abstract

Ebola virus infections lead to severe hemorrhagic fevers in humans and nonhuman primates; and human fatality rates are as high as 67%-90%. Since the Ebola virus was discovered in 1976, the only available treatments have been medical support or the emergency administration of experimental drugs. The absence of licensed vaccines and drugs against the Ebola virus impedes the prevention of viral infection. In this study, we generated recombinant baculoviruses (rBV) expressing the Sudan virus (SUDV) matrix structural protein (VP40) (rBV-VP40-VP40) or the SUDV glycoprotein (GP) (rBV-GP-GP), and SUDV virus-like particles (VLPs) were produced by co-infection of Sf9 cells with rBV-SUDV-VP40 and rBV-SUDV-GP. The expression of SUDV VP40 and GP in SUDV VLPs was demonstrated by IFA and Western blot analysis. Electron microscopy results demonstrated that SUDV VLPs had a filamentous morphology. The immunogenicity of SUDV VLPs produced in insect cells was evaluated by the immunization of mice. The analysis of antibody responses showed that mice vaccinated with SUDV VLPs and the adjuvant Montanide ISA 201 produced SUDV GP-specific IgG antibodies. Sera from SUDV VLP-immunized mice were able to block infection by SUDV GP pseudotyped HIV, indicating that a neutralizing antibody against the SUDV GP protein was produced. Furthermore, the activation of B cells in the group immunized with VLPs mixed with Montanide ISA 201 was significant one week after the primary immunization. Vaccination with the SUDV VLPs markedly increased the frequency of antigen-specific cells secreting type 1 and type 2 cytokines. To study the therapeutic effects of SUDV antibodies, horses were immunized with SUDV VLPs emulsified in Freund’s complete adjuvant or Freund’s incomplete adjuvant. The results showed that horses could produce SUDV GP-specific antibodies and neutralizing antibodies. These results showed that SUDV VLPs demonstrate excellent immunogenicity and represent a promising approach for vaccine development against SUDV infection. Further, these horse anti-SUDV purified immunoglobulins lay a foundation for SUDV therapeutic drug research.

KEYWORDS: Sudan virus; horse; mice; purified IgG; vaccine; virus-like particle

PMID: 31947873 DOI: 10.3390/v12010064

Keywords: Ebolavirus; Sudan virus; Vaccines; Animal models.

——

An #Evolutionary #Insight into Emerging #Ebolavirus #Strains Isolated in #Africa (J Med Virol., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

J Med Virol. 2019 Nov 8. doi: 10.1002/jmv.25627. [Epub ahead of print]

An Evolutionary Insight into Emerging Ebolavirus Strains Isolated in Africa.

Pereira-Gomez M1,2, Lopez-Tort F3, Fajardo A1, Cristina J1.

Author information: 1 Laboratorio de Virología Molecular, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo, 11400, Uruguay. 2 Laboratorio de Inmunovirología, Institut Pasteur de Montevideo, Mataojo 2020, 11400, Montevideo, Uruguay. 3 Laboratorio de Virología Molecular, Sede Salto, Centro Universitario Regional Litoral Norte, Universidad de la República, Gral. Rivera 1350, 50000, Salto, Uruguay.

 

Abstract

BACKGROUND:

On July 19th, 2019, the World Health Organization declared the current Ebola virus (EBOV) outbreak in Congo Democratic Republic (COD) a public health emergency of international concern. To address the potential threat of EBOV evolution outpacing antibody treatment and vaccine efforts, a detailed evolutionary analysis of EBOV strains circulating in different African countries was performed.

METHODS:

Genome composition of EBOV strains were studied using multivariate statistical analysis. To investigate the patterns of evolution of EBOV strains, a Bayesian Markov Chain Monte Carlo (MCMC) approach was used.

RESULTS:

Two different genetic lineages, with a distinct genome composition gave rise to the recent EBOV outbreaks in central and western Africa. Strains isolated in COD in 2018 fall into two different genetic clusters, according to their geographical location of isolation. Different amino acid substitutions among strains from these two clusters have been found, particularly in NP, GP and L proteins. Significant differences in codon and amino acid usage among clusters were found.

CONCLUSION:

Strains isolated in COD in 2018 belongs to two distinct genetic clusters, with distinct codon and amino acid usage. Geographical diversity plays an important role in shaping the molecular evolution of EBOV populations.

This article is protected by copyright. All rights reserved.

KEYWORDS: Ebolavirus; GP protein; codon usage; evolution

PMID: 31702053 DOI: 10.1002/jmv.25627

Keywords: Ebolavirus; Ebola; DRC; Genetics.

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Lek-associated movement of a putative #Ebolavirus #reservoir, the hammer-headed fruit #bat (Hypsignathus monstrosus), in northern Republic of #Congo (PLoS One, abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

PLoS One. 2019 Oct 1;14(10):e0223139. doi: 10.1371/journal.pone.0223139. eCollection 2019.

Lek-associated movement of a putative Ebolavirus reservoir, the hammer-headed fruit bat (Hypsignathus monstrosus), in northern Republic of Congo.

Olson SH1, Bounga G2, Ondzie A2, Bushmaker T3, Seifert SN3, Kuisma E2, Taylor DW1, Munster VJ3, Walzer C1,4.

Author information: 1 Wildlife Conservation Society, Health Program, Bronx, New York, United States of America. 2 Wildlife Conservation Society, Brazzaville, Republic of Congo. 3 Virus Ecology Section, Laboratory of Virology, Division of Intramural Research, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, Montana, United States of America. 4 Research Institute of Wildlife Ecology, University of Veterinary Medicine Vienna, Vienna, Austria.

 

Abstract

The biology and ecology of Africa’s largest fruit bat remains largely understudied and enigmatic despite at least two highly unusual attributes. The acoustic lek mating behavior of the hammer-headed bat (Hypsignathus monstrosus) in the Congo basin was first described in the 1970s. More recently molecular testing implicated this species and other African bats as potential reservoir hosts for Ebola virus and it was one of only two fruit bat species epidemiologically linked to the 2008 Luebo, Democratic Republic of Congo, Ebola outbreak. Here we share findings from the first pilot study of hammer-headed bat movement using GPS tracking and accelerometry units and a small preceding radio-tracking trial at an apparent lekking site. The radio-tracking revealed adult males had high rates of nightly visitation to the site compared to females (only one visit) and that two of six females day-roosted ~100 m west of Libonga, the nearest village that is ~1.6 km southwest. Four months later, in mid-April 2018, five individual bats, comprised of four males and one female, were tracked from two to 306 days, collecting from 67 to 1022 GPS locations. As measured by mean distance to the site and proportion of nightly GPS locations within 1 km of the site (percent visitation), the males were much more closely associated with the site (mean distance 1.4 km; 51% visitation), than the female (mean 5.5 km; 2.2% visitation). Despite the small sample size, our tracking evidence supports our original characterization of the site as a lek, and the lek itself is much more central to male than female movement. Moreover, our pilot demonstrates the technical feasibility of executing future studies on hammer-headed bats that will help fill problematic knowledge gaps about zoonotic spillover risks and the conservation needs of fruit bats across the continent.

PMID: 31574111 DOI: 10.1371/journal.pone.0223139

Keywords: Ebolavirus; Wildlife; Bats; Rep. of Congo.

——

Long-term #wildlife #mortality surveillance in northern #Congo: a model for the detection of #Ebola virus disease #epizootics (Philos Trans R Soc B., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Philos Trans R Soc Lond B Biol Sci. 2019 Sep 30;374(1782):20180339. doi: 10.1098/rstb.2018.0339. Epub 2019 Aug 12.

Long-term wildlife mortality surveillance in northern Congo: a model for the detection of Ebola virus disease epizootics.

Kuisma E1, Olson SH2, Cameron KN2, Reed PE2, Karesh WB3, Ondzie AI1, Akongo MJ1, Kaba SD1, Fischer RJ4, Seifert SN4, Muñoz-Fontela C5, Becker-Ziaja B6, Escudero-Pérez B5, Goma-Nkoua C7, Munster VJ4, Mombouli JV7.

Author information: 1 Wildlife Conservation Society, Wildlife Health Program, 151 Avenue du General de Gaulle, BP14537 Brazzaville, Republic of Congo. 2 Wildlife Conservation Society, Wildlife Health Program, 2300 Southern Boulevard, Bronx, New York, NY 10460, USA. 3 Health and Policy, EcoHealth Alliance, 460 West 34th Street, New York, NY 10001, USA. 4 Laboratory of Virology, Virus Ecology Unit, Division of Intramural Research, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, 903s 4th street, Hamilton, MT, USA. 5 Bernhard Nocht Institute for Tropical Medicine and German Center for Infection Research DZIF, Bernhard Nocht Strasse 74, 20359 Hamburg, Germany. 6 Robert Koch-Institut, Seestraße 10, 13353 Berlin, Germany. 7 Service d’Epidémiologie Moléculaire, Laboratoire National de Santé Publique, Avenue du General de Gaulle, BP120 Brazzaville, Republic of Congo.

 

Abstract

Ebolavirus (EBOV) has caused disease outbreaks taking thousands of lives, costing billions of dollars in control efforts and threatening great ape populations. EBOV ecology is not fully understood but infected wildlife and consumption of animal carcasses have been linked to human outbreaks, especially in the Congo Basin. Partnering with the Congolese Ministry of Health, we conducted wildlife mortality surveillance and educational outreach in the northern Republic of Congo (RoC). Designed for EBOV detection and to alert public health authorities, we established a low-cost wildlife mortality reporting network covering 50 000 km2. Simultaneously, we delivered educational outreach promoting behavioural change to over 6600 people in rural northern RoC. We achieved specimen collection by training project staff on a safe sampling protocol and equipping geographically distributed bases with sampling kits. We established in-country diagnostics for EBOV testing, reducing diagnostic turnaround time to 3 days and demonstrated the absence of EBOV in 58 carcasses. Central Africa remains a high-risk EBOV region, but RoC, home to the largest remaining populations of great apes, has not had an epidemic since 2005. This effort continues to function as an untested early warning system in RoC, where people and great apes have died from past Ebola virus disease outbreaks. This article is part of the theme issue ‘Dynamic and integrative approaches to understanding pathogen spillover’.

KEYWORDS: Ebola spillover; One Health; carcass; community outreach; great ape; surveillance

PMID: 31401969 DOI: 10.1098/rstb.2018.0339

Keywords: Ebolavirus; Wildlife: Rep. of Congo.

——

#Ecological #indicators of #mammal exposure to #Ebolavirus (Philos Trans R Soc B., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Philos Trans R Soc Lond B Biol Sci. 2019 Sep 30;374(1782):20180337. doi: 10.1098/rstb.2018.0337. Epub 2019 Aug 12.

Ecological indicators of mammal exposure to Ebolavirus.

Schmidt JP1, Maher S2, Drake JM1, Huang T3, Farrell MJ1, Han BA3.

Author information: 1 Odum School of Ecology and Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA 30602, USA. 2 Department of Biology, Missouri State University, 901 S. National Ave, Springfield, MO 65897, USA. 3 Cary Institute of Ecosystem Studies, 2801 Sharon Turnpike, Millbrook, NY 12545, USA.

 

Abstract

Much of the basic ecology of Ebolavirus remains unresolved despite accumulating disease outbreaks, viral strains and evidence of animal hosts. Because human Ebolavirus epidemics have been linked to contact with wild mammals other than bats, traits shared by species that have been infected by Ebolavirus and their phylogenetic distribution could suggest ecological mechanisms contributing to human Ebolavirus spillovers. We compiled data on Ebolavirus exposure in mammals and corresponding data on life-history traits, movement, and diet, and used boosted regression trees (BRT) to identify predictors of exposure and infection for 119 species (hereafter hosts). Mapping the phylogenetic distribution of presumptive Ebolavirus hosts reveals that they are scattered across several distinct mammal clades, but concentrated among Old World fruit bats, primates and artiodactyls. While sampling effort was the most important predictor, explaining nearly as much of the variation among hosts as traits, BRT models distinguished hosts from all other species with greater than 97% accuracy, and revealed probable Ebolavirus hosts as large-bodied, frugivorous, and with slow life histories. Provisionally, results suggest that some insectivorous bat genera, Old World monkeys and forest antelopes should receive priority in Ebolavirus survey efforts. This article is part of the theme issue ‘Dynamic and integrative approaches to understanding pathogen spillover’.

KEYWORDS: Ebola; boosted regression trees; comparative analysis; frugivory; host

PMID: 31401967 DOI: 10.1098/rstb.2018.0337

Keywords: Ebolavirus; Wildlife; Bats.

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#Inhibition of #Ebola Virus by a Molecularly Engineered #Banana #Lectin (PLoS Negl Trop Dis., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

PLoS Negl Trop Dis. 2019 Jul 29;13(7):e0007595. doi: 10.1371/journal.pntd.0007595. [Epub ahead of print]

Inhibition of Ebola Virus by a Molecularly Engineered Banana Lectin.

Covés-Datson EM1,2, Dyall J3, DeWald LE3, King SR4, Dube D4, Legendre M4, Nelson E5, Drews KC6, Gross R3, Gerhardt DM3, Torzewski L3, Postnikova E3, Liang JY3, Ban B5,7, Shetty J7, Hensley LE3, Jahrling PB3,8, Olinger GG Jr3, White JM5,9, Markovitz DM4,10,11,12.

Author information: 1 Medical Scientist Training Program, University of Michigan, Ann Arbor, Michigan, United States of America. 2 Department of Microbiology & Immunology, University of Michigan, Ann Arbor, Michigan, United States of America. 3 Integrated Research Facility, Division of Clinical Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Frederick, Maryland, United States of America. 4 Division of Infectious Diseases, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America. 5 Department of Cell Biology, University of Virginia, Charlottesville, Virginia, United States of America. 6 Department of Pathology, University of Virginia, Charlottesville, Virginia, United States of America. 7 Antibody Engineering and Technology Core, University of Virginia, Charlottesville, Virginia, United States of America. 8 Emerging Viral Pathogens Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Frederick, Maryland, United States of America. 9 Department of Microbiology, University of Virginia, Charlottesville, Virginia, United States of America. 10 Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan, United States of America. 11 Graduate Program in Immunology, University of Michigan, Ann Arbor, Michigan, United States of America. 12 Cancer Biology Program, University of Michigan, Ann Arbor, Michigan, United States of America.

 

Abstract

Ebolaviruses cause an often rapidly fatal syndrome known as Ebola virus disease (EVD), with average case fatality rates of ~50%. There is no licensed vaccine or treatment for EVD, underscoring the urgent need to develop new anti-ebolavirus agents, especially in the face of an ongoing outbreak in the Democratic Republic of the Congo and the largest ever outbreak in Western Africa in 2013-2016. Lectins have been investigated as potential antiviral agents as they bind glycans present on viral surface glycoproteins, but clinical use of them has been slowed by concerns regarding their mitogenicity, i.e. ability to cause immune cell proliferation. We previously engineered a banana lectin (BanLec), a carbohydrate-binding protein, such that it retained antiviral activity but lost mitogenicity by mutating a single amino acid, yielding H84T BanLec (H84T). H84T shows activity against viruses containing high-mannose N-glycans, including influenza A and B, HIV-1 and -2, and hepatitis C virus. Since ebolavirus surface glycoproteins also contain many high-mannose N-glycans, we assessed whether H84T could inhibit ebolavirus replication. H84T inhibited Ebola virus (EBOV) replication in cell cultures. In cells, H84T inhibited both virus-like particle (VLP) entry and transcription/replication of the EBOV mini-genome at high micromolar concentrations, while inhibiting infection by transcription- and replication-competent VLPs, which measures the full viral life cycle, in the low micromolar range. H84T did not inhibit assembly, budding, or release of VLPs. These findings suggest that H84T may exert its anti-ebolavirus effect(s) by blocking both entry and transcription/replication. In a mouse model, H84T partially (maximally, ~50-80%) protected mice from an otherwise lethal mouse-adapted EBOV infection. Interestingly, a single dose of H84T pre-exposure to EBOV protected ~80% of mice. Thus, H84T shows promise as a new anti-ebolavirus agent with potential to be used in combination with vaccination or other agents in a prophylactic or therapeutic regimen.

PMID: 31356611 DOI: 10.1371/journal.pntd.0007595

Keywords: Ebolavirus; Antivirals; Lectins; Animal models.

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Conserved microsatellites may contribute to stem-loop structures in 5′, 3′ terminals of #Ebolavirus #genomes (Bioche Biophys Res Commun., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Biochem Biophys Res Commun. 2019 May 8. pii: S0006-291X(19)30851-4. doi: 10.1016/j.bbrc.2019.04.192. [Epub ahead of print]

Conserved microsatellites may contribute to stem-loop structures in 5′, 3′ terminals of Ebolavirus genomes.

Li D1, Zhang H1, Peng S1, Pan S1, Tan Z2.

Author information: 1 Bioinformatics Center, College of Biology, Hunan University, Changsha, China. 2 Bioinformatics Center, College of Biology, Hunan University, Changsha, China. Electronic address: zhongyang@hnu.edu.cn.

 

Abstract

Microsatellites (SSRs) are ubiquitous in coding and non-coding regions of the Ebolavirus genomes. We synthetically analyzed the microsatellites in whole-genome and terminal regions of 219 Ebolavirus genomes from five species. The Ebolavirus sequences were observed with small intraspecies variations and large interspecific variations, especially in the terminal non-coding regions. Only five conserved microsatellites were detected in the complete genomes, and four of them which well base-paired to help forming conserved stem-loop structures mainly appeared in the terminal non-coding regions. These results suggest that the conserved microsatellites may be evolutionary selected to form conserved secondary structures in 5′, 3′ terminals of Ebolavirus genomes. It may help to understand the biological significance of microsatellites in Ebolavirus and also other virus genomes.

Copyright © 2019 Elsevier Inc. All rights reserved.

KEYWORDS: Conserved microsatellite; Conserved stem-loop structure; Ebolavirus; Evolutionary selection

PMID: 31078274 DOI: 10.1016/j.bbrc.2019.04.192

Keywords: Ebolavirus; Virology.

—–

Cross-reactive neutralizing #human #survivor monoclonal #antibody BDBV223 targets the #ebolavirus stalk (Nat Commun., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Nat Commun. 2019 Apr 17;10(1):1788. doi: 10.1038/s41467-019-09732-7.

Cross-reactive neutralizing human survivor monoclonal antibody BDBV223 targets the ebolavirus stalk.

King LB1, West BR1, Moyer CL1, Gilchuk P2, Flyak A3, Ilinykh PA4,5, Bombardi R2, Hui S1, Huang K4,5, Bukreyev A4,5,6, Crowe JE Jr2,3, Saphire EO7,8,9.

Author information: 1 Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, 92037, USA. 2 Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, 37232, USA. 3 Departments of Pediatrics, Pathology, and Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA. 4 Department of Pathology, University of Texas Medical Branch, Galveston, TX, 77555, USA. 5 Galveston National Laboratory, Galveston, TX, 77555, USA. 6 Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, TX, 77555, USA. 7 Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, 92037, USA. erica@lji.org. 8 Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA. erica@lji.org. 9 La Jolla Institute for Immunology La Jolla, CA, 92037, USA. erica@lji.org.

 

Abstract

Three Ebolavirus genus viruses cause lethal disease and lack targeted therapeutics: Ebola virus, Sudan virus and Bundibugyo virus. Monoclonal antibody (mAb) cocktails against the surface glycoprotein (GP) present a potential therapeutic strategy. Here we report two crystal structures of the antibody BDBV223, alone and complexed with its GP2 stalk epitope, an interesting site for therapeutic/vaccine design due to its high sequence conservation among ebolaviruses. BDBV223, identified in a human survivor of Bundibugyo virus disease, neutralizes both Bundibugyo virus and Ebola virus, but not Sudan virus. Importantly, the structure suggests that BDBV223 binding interferes with both the trimeric bundle assembly of GP and the viral membrane by stabilizing a conformation in which the monomers are separated by GP lifting or bending. Targeted mutagenesis of BDBV223 to enhance SUDV GP recognition indicates that additional determinants of antibody binding likely lie outside the visualized interactions, and perhaps involve quaternary assembly or membrane-interacting regions.

PMID: 30996276 DOI: 10.1038/s41467-019-09732-7

Keywords: Ebola; Monoclonal antibodies.

——

#Ebolavirus #polymerase uses an unconventional #genome #replication mechanism (Proc Natl Acad Sci USA, abstract)

[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]

Ebolavirus polymerase uses an unconventional genome replication mechanism

Laure R. Deflubé, Tessa N. Cressey, Adam J. Hume, Judith Olejnik, Elaine Haddock, Friederike Feldmann, Hideki Ebihara, Rachel Fearns, and Elke Mühlberger

PNAS published ahead of print April 8, 2019 / DOI: https://doi.org/10.1073/pnas.1815745116

Edited by Robert A. Lamb, Howard Hughes Medical Institute and Northwestern University, Evanston, IL, and approved March 14, 2019 (received for review September 11, 2018)

 

Significance

Ebolaviruses belong to the group of nonsegmented negative strand (NNS) RNA viruses. Most members of the Ebolavirus genus cause severe disease in humans. Here, we report that ebolaviruses have evolved a genome replication mechanism that distinguishes them from the other NNS RNA viruses. The ebolavirus replication strategy includes the addition of a nontemplated 3′ nucleotide at the genome ends which may aid in avoiding antiviral recognition. Our data highlight the need for more research on NNS RNA virus replication strategies to reveal commonalities between virus families as well as unique features. Dissecting the replication mechanisms of NNS RNA viruses, including ebolaviruses, paves the way for the development of broad-spectrum antivirals that target the viral replication complexes, thereby preventing virus amplification.

 

Abstract

Most nonsegmented negative strand (NNS) RNA virus genomes have complementary 3′ and 5′ terminal nucleotides because the promoters at the 3′ ends of the genomes and antigenomes are almost identical to each other. However, according to published sequences, both ends of ebolavirus genomes show a high degree of variability, and the 3′ and 5′ terminal nucleotides are not complementary. If correct, this would distinguish the ebolaviruses from other NNS RNA viruses. Therefore, we investigated the terminal genomic and antigenomic nucleotides of three different ebolavirus species, Ebola (EBOV), Sudan, and Reston viruses. Whereas the 5′ ends of ebolavirus RNAs are highly conserved with the sequence ACAGG-5′, the 3′ termini are variable and are typically 3′-GCCUGU, ACCUGU, or CCUGU. A small fraction of analyzed RNAs had extended 3′ ends. The majority of 3′ terminal sequences are consistent with a mechanism of nucleotide addition by hairpin formation and back-priming. Using single-round replicating EBOV minigenomes, we investigated the effect of the 3′ terminal nucleotide on viral replication and found that the EBOV polymerase initiates replication opposite the 3′-CCUGU motif regardless of the identity of the 3′ terminal nucleotide(s) and of the position of this motif relative to the 3′ end. Deletion or mutation of the first residue of the 3′-CCUGU motif completely abolished replication initiation, suggesting a crucial role of this nucleotide in directing initiation. Together, our data show that ebolaviruses have evolved a unique replication strategy among NNS RNA viruses resulting in 3′ overhangs. This could be a mechanism to avoid antiviral recognition.

Ebola virus replication – Ebola virus genome ends – variable 3′ genome ends – ebolavirus replication initiation – nonsegmented negative strand RNA virus replication

 

Footnotes

1 L.R.D., T.N.C., and A.J.H. contributed equally to this work.

2 To whom correspondence may be addressed. Email: rfearns@bu.edu or muehlber@bu.edu.

Author contributions: L.R.D., R.F., and E.M. designed research; L.R.D., T.N.C., A.J.H., and J.O. performed research; E.H., F.F., and H.E. contributed new reagents/analytic tools; L.R.D., T.N.C., A.J.H., R.F., and E.M. analyzed data; and L.R.D., T.N.C., A.J.H., R.F., and E.M. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1815745116/-/DCSupplemental.

Published under the PNAS license.

Keywords: Ebolavirus; Antivirals.

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Achieving cross-reactivity with #panebolavirus #antibodies (Curr Opin Virol., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Curr Opin Virol. 2019 Mar 15;34:140-148. doi: 10.1016/j.coviro.2019.01.003. [Epub ahead of print]

Achieving cross-reactivity with pan-ebolavirus antibodies.

King LB1, Milligan JC1, West BR1, Schendel SL1, Ollmann Saphire E2.

Author information: 1 Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA. 2 Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA; Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA. Electronic address: erica@scripps.edu.

 

Abstract

Filoviruses are the causative agents of highly lethal outbreaks in sub-Saharan Africa. Although an experimental vaccine and several therapeutics are being deployed in the Democratic Republic of Congo to combat the ongoing Ebola virus outbreak, these therapies are specific for only one filovirus species. There is currently significant interest in developing broadly reactive monoclonal antibodies (mAbs) with utility against the variety of ebolaviruses that may emerge. Thus far, the primary target of these mAbs has been the viral spike glycoprotein (GP). Here we present an overview of GP-targeted antibodies that exhibit broad reactivity and the structural characteristics that could confer this cross-reactivity. We also discuss how these structural features could be leveraged to design vaccine antigens that elicit cross-reactive antibodies.

Copyright © 2019 Elsevier B.V. All rights reserved.

PMID: 30884329 DOI: 10.1016/j.coviro.2019.01.003

Keywords: Ebola; Filovirus; Monoclonal antibodies.

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