Publications by authors named "Alain Kohl"

101 Publications

Oligodendrocytes are susceptible to Zika virus infection in a mouse model of perinatal exposure: Implications for CNS complications.

Glia 2021 May 4. Epub 2021 May 4.

College of Medical, Veterinary, and Life Sciences, Institute of Infection, Immunity and Inflammation, Glasgow, UK.

Some children with proven intrauterine Zika virus (ZIKV) infection who were born asymptomatic subsequently manifested neurodevelopmental delays, pointing to impairment of development perinatally and postnatally. To model this, we infected postnatal day (P) 5-6 (equivalent to the perinatal period in humans) susceptible mice with a mammalian cell-propagated ZIKV clinical isolate from the Brazilian outbreak in 2015. All infected mice appeared normal up to 4 days post-intraperitoneal inoculation (dpi), but rapidly developed severe clinical signs at 5-6 dpi. All nervous tissue examined at 5/6 dpi appeared grossly normal. However, anti-ZIKV positive cells were observed in the optic nerve, brain, and spinal cord; predominantly in white matter. Co-labeling with cell type specific markers demonstrated oligodendrocytes and astrocytes support productive infection. Rarely, ZIKV positive neurons were observed. In spinal cord white matter, which we examined in detail, apoptotic cells were evident; the density of oligodendrocytes was significantly reduced; and there was localized microglial reactivity including expression of the NLRP3 inflammasome. Together, our observations demonstrate that a clinically relevant ZIKV isolate can directly impact oligodendrocytes. As primary oligodendrocyte cell death can lead later to secondary autoimmune demyelination, our observations may help explain neurodevelopmental delays in infants appearing asymptomatic at birth and commend lifetime surveillance.
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http://dx.doi.org/10.1002/glia.24010DOI Listing
May 2021

Modified recombinant human IgG1-Fc is superior to natural IVIG at inhibiting immune-mediated demyelination.

Immunology 2021 Apr 20. Epub 2021 Apr 20.

Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, United Kingdom.

Intravenous immunoglobulin (IVIG) is an established treatment for numerous autoimmune conditions. Although Fc fragments derived from IVIG have shown efficacy in controlling immune thrombocytopenia (ITP) in children, the mechanisms of action are unclear and controversial. The aim of this study is to dissect IVIG effector mechanisms using further adapted Fc fragments on demyelination in an ex vivo model of the central nervous system (CNS)-immune interface. Using organotypic cerebellar slice cultures (OSC) from transgenic mice we induced extensive immune-mediated demyelination and oligodendrocyte loss with an antibody specific for myelin oligodendrocyte glycoprotein (MOG) and complement. Protective effects of adapted Fc fragments were assessed by live imaging of GFP expression, immunohistochemistry and confocal microscopy. Cysteine and glycan adapted Fc fragments protected OSC from demyelination in a dose-dependent manner where equimolar concentrations of either IVIG or control Fc were ineffective. The protective effects of the adapted Fc fragments are partly attributed to interference with complement-mediated oligodendroglia damage. Transcriptome analysis ruled out signatures associated with inflammatory or innate immune responses. Taken together our findings show that recombinant biomimetics can be made that are at least two hundred-fold more effective than IVIG in controlling demyelination by anti-MOG antibodies.
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http://dx.doi.org/10.1111/imm.13341DOI Listing
April 2021

Subgenomic RNA identification in SARS-CoV-2 genomic sequencing data.

Genome Res 2021 04 15;31(4):645-658. Epub 2021 Mar 15.

Centre for Virus Research, The University of Glasgow, Glasgow G61 1QH, United Kingdom.

We have developed periscope, a tool for the detection and quantification of subgenomic RNA (sgRNA) in SARS-CoV-2 genomic sequence data. The translation of the SARS-CoV-2 RNA genome for most open reading frames (ORFs) occurs via RNA intermediates termed "subgenomic RNAs." sgRNAs are produced through discontinuous transcription, which relies on homology between transcription regulatory sequences (TRS-B) upstream of the ORF start codons and that of the TRS-L, which is located in the 5' UTR. TRS-L is immediately preceded by a leader sequence. This leader sequence is therefore found at the 5' end of all sgRNA. We applied periscope to 1155 SARS-CoV-2 genomes from Sheffield, United Kingdom, and validated our findings using orthogonal data sets and in vitro cell systems. By using a simple local alignment to detect reads that contain the leader sequence, we were able to identify and quantify reads arising from canonical and noncanonical sgRNA. We were able to detect all canonical sgRNAs at the expected abundances, with the exception of ORF10. A number of recurrent noncanonical sgRNAs are detected. We show that the results are reproducible using technical replicates and determine the optimum number of reads for sgRNA analysis. In VeroE6 +/- cell lines, periscope can detect the changes in the kinetics of sgRNA in orthogonal sequencing data sets. Finally, variants found in genomic RNA are transmitted to sgRNAs with high fidelity in most cases. This tool can be applied to all sequenced COVID-19 samples worldwide to provide comprehensive analysis of SARS-CoV-2 sgRNA.
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http://dx.doi.org/10.1101/gr.268110.120DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8015849PMC
April 2021

A plasmid DNA-launched SARS-CoV-2 reverse genetics system and coronavirus toolkit for COVID-19 research.

PLoS Biol 2021 02 25;19(2):e3001091. Epub 2021 Feb 25.

MRC-University of Glasgow Centre for Virus Research (CVR), Glasgow, United Kingdom.

The recent emergence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the underlying cause of Coronavirus Disease 2019 (COVID-19), has led to a worldwide pandemic causing substantial morbidity, mortality, and economic devastation. In response, many laboratories have redirected attention to SARS-CoV-2, meaning there is an urgent need for tools that can be used in laboratories unaccustomed to working with coronaviruses. Here we report a range of tools for SARS-CoV-2 research. First, we describe a facile single plasmid SARS-CoV-2 reverse genetics system that is simple to genetically manipulate and can be used to rescue infectious virus through transient transfection (without in vitro transcription or additional expression plasmids). The rescue system is accompanied by our panel of SARS-CoV-2 antibodies (against nearly every viral protein), SARS-CoV-2 clinical isolates, and SARS-CoV-2 permissive cell lines, which are all openly available to the scientific community. Using these tools, we demonstrate here that the controversial ORF10 protein is expressed in infected cells. Furthermore, we show that the promising repurposed antiviral activity of apilimod is dependent on TMPRSS2 expression. Altogether, our SARS-CoV-2 toolkit, which can be directly accessed via our website at https://mrcppu-covid.bio/, constitutes a resource with considerable potential to advance COVID-19 vaccine design, drug testing, and discovery science.
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http://dx.doi.org/10.1371/journal.pbio.3001091DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7906417PMC
February 2021

Interactions of Viral Proteins from Pathogenic and Low or Non-Pathogenic Orthohantaviruses with Human Type I Interferon Signaling.

Viruses 2021 Jan 19;13(1). Epub 2021 Jan 19.

Unité des Stratégies Antivirales, Institut Pasteur, 75015 Paris, France.

Rodent-borne orthohantaviruses are asymptomatic in their natural reservoir, but they can cause severe diseases in humans. Although an exacerbated immune response relates to hantaviral pathologies, orthohantaviruses have to antagonize the antiviral interferon (IFN) response to successfully propagate in infected cells. We studied interactions of structural and nonstructural (NSs) proteins of pathogenic Puumala (PUUV), low-pathogenic Tula (TULV), and non-pathogenic Prospect Hill (PHV) viruses, with human type I and III IFN (IFN-I and IFN-III) pathways. The NSs proteins of all three viruses inhibited the RIG-I-activated IFNβ promoter, while only the glycoprotein precursor (GPC) of PUUV, or its cleavage product Gn/Gc, and the nucleocapsid (N) of TULV inhibited it. Moreover, the GPC of both PUUV and TULV antagonized the promoter of IFN-stimulated responsive elements (ISRE). Different viral proteins could thus contribute to inhibition of IFNβ response in a viral context. While PUUV and TULV strains replicated similarly, whether expressing entire or truncated NSs proteins, only PUUV encoding a wild type NSs protein led to late IFN expression and activation of IFN-stimulated genes (ISG). This, together with the identification of particular domains of NSs proteins and different biological processes that are associated with cellular proteins in complex with NSs proteins, suggested that the activation of IFN-I is probably not the only antiviral pathway to be counteracted by orthohantaviruses and that NSs proteins could have multiple inhibitory functions.
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http://dx.doi.org/10.3390/v13010140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7835746PMC
January 2021

Zika Virus Infection Leads to Demyelination and Axonal Injury in Mature CNS Cultures.

Viruses 2021 Jan 11;13(1). Epub 2021 Jan 11.

MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK.

Understanding how Zika virus (; ZIKV) affects neural cells is paramount in comprehending pathologies associated with infection. Whilst the effects of ZIKV in neural development are well documented, impact on the adult nervous system remains obscure. Here, we investigated the effects of ZIKV infection in established mature myelinated central nervous system (CNS) cultures. Infection incurred damage to myelinated fibers, with ZIKV-positive cells appearing when myelin damage was first detected as well as axonal pathology, suggesting the latter was a consequence of oligodendroglia infection. Transcriptome analysis revealed host factors that were upregulated during ZIKV infection. One such factor, CCL5, was validated in vitro as inhibiting myelination. Transferred UV-inactivated media from infected cultures did not damage myelin and axons, suggesting that viral replication is necessary to induce the observed effects. These data show that ZIKV infection affects CNS cells even after myelination-which is critical for saltatory conduction and neuronal function-has taken place. Understanding the targets of this virus across developmental stages including the mature CNS, and the subsequent effects of infection of cell types, is necessary to understand effective time frames for therapeutic intervention.
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http://dx.doi.org/10.3390/v13010091DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7827345PMC
January 2021

Enhanced Zika virus susceptibility of globally invasive populations.

Science 2020 11;370(6519):991-996

Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA.

The drivers and patterns of zoonotic virus emergence in the human population are poorly understood. The mosquito is a major arbovirus vector native to Africa that invaded most of the world's tropical belt over the past four centuries, after the evolution of a "domestic" form that specialized in biting humans and breeding in water storage containers. Here, we show that human specialization and subsequent spread of out of Africa were accompanied by an increase in its intrinsic ability to acquire and transmit the emerging human pathogen Zika virus. Thus, the recent evolution and global expansion of promoted arbovirus emergence not solely through increased vector-host contact but also as a result of enhanced vector susceptibility.
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http://dx.doi.org/10.1126/science.abd3663DOI Listing
November 2020

Species: A Review of Current Knowledge.

Insects 2020 Oct 30;11(11). Epub 2020 Oct 30.

MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, Scotland, UK.

The increasing global incidence of mosquito-borne infections is driving a need for effective control methods. Vector populations have expanded their geographical ranges, while increasing resistance to chemical insecticides and a lack of effective treatments or vaccines has meant that the development of vector control methods is essential in the fight against mosquito-transmitted diseases. This review will focus on , a non-hematophagous mosquito genus which is a natural predator of vector species and may be exploited as a biological control agent. Their effectiveness in this role has been strongly debated for many years and early trials have been marred by misinformation and incomplete descriptions. Here, we draw together current knowledge of the general biology of and discuss how this updated information will benefit their role in an integrated vector management program.
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http://dx.doi.org/10.3390/insects11110747DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7693308PMC
October 2020

Zika Virus-Like Particles Bearing a Covalent Dimer of Envelope Protein Protect Mice from Lethal Challenge.

J Virol 2020 12 9;95(1). Epub 2020 Dec 9.

MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom

Zika virus (ZIKV) envelope (E) protein is the major target of neutralizing antibodies in infected hosts and thus represents a candidate of interest for vaccine design. However, a major concern in the development of vaccines against ZIKV and the related dengue virus is the induction of cross-reactive poorly neutralizing antibodies that can cause antibody-dependent enhancement (ADE) of infection. This risk necessitates particular care in vaccine design. Specifically, the engineered immunogens should have their cross-reactive epitopes masked, and they should be optimized for eliciting virus-specific strongly neutralizing antibodies upon vaccination. Here, we developed ZIKV subunit- and virus-like particle (VLP)-based vaccines displaying E in its wild-type form or E locked in a covalently linked dimeric (cvD) conformation to enhance the exposure of E dimers to the immune system. Compared with their wild-type derivatives, cvD immunogens elicited antibodies with a higher capacity to neutralize virus infection in cultured cells. More importantly, these immunogens protected animals from lethal challenge with both the African and Asian lineages of ZIKV, impairing virus dissemination to brain and sexual organs. Moreover, the locked conformation of E reduced the exposure of epitopes recognized by cross-reactive antibodies and therefore showed a lower potential to induce ADE Our data demonstrated a higher efficacy of the VLPs in comparison with that of the soluble dimer and support VLP-cvD as a promising ZIKV vaccine. Infection with Zika virus (ZIKV) leads to the production by the host of antibodies that target the viral surface envelope (E) protein. A subset of these antibodies can inhibit virus infection, thus making E a suitable candidate for the development of vaccine against the virus. However, the anti-ZIKV E antibodies can cross-react with the E protein of the related dengue virus on account of the high level of similarity exhibited by the two viral proteins. Such a scenario may lead to severe dengue disease. Therefore, the design of a ZIKV vaccine requires particular care. Here, we tested two candidate vaccines containing a recombinant form of the ZIKV E protein that is forced in a covalently stable dimeric conformation (cvD). They were generated with an explicit aim to reduce the exposure of the cross-reactive epitopes. One vaccine is composed of a soluble form of the E protein (sE-cvD), the other is a more complex virus-like particle (VLP-cvD). We used the two candidate vaccines to immunize mice and later infected them with ZIKV. The animals produced a high level of inhibitory antibodies and were protected from the infection. The VLP-cvD was the most effective, and we believe it represents a promising ZIKV vaccine candidate.
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http://dx.doi.org/10.1128/JVI.01415-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7737734PMC
December 2020

Generation of a reporter yellow fever virus for high throughput antiviral assays.

Antiviral Res 2020 11 24;183:104939. Epub 2020 Sep 24.

MRC-University of Glasgow, Centre for Virus Research, Glasgow, UK. Electronic address:

Yellow fever virus (YFV), a member of the Flaviviridae family, is an arthropod-borne virus that can cause severe disease in humans with a lethality rate of up to 60%. Since 2017, increases in YFV activity in areas of South America and Africa have been described. Although a vaccine is available, named strain 17D (Theiler and Smith, 1937), it is contraindicated for use in the elderly, expectant mothers, immunocompromised people, among others. To this day there is no antiviral treatment against YFV to reduce the severity of viral infection. Here, we used a circular polymerase extension reaction (CPER)-based reverse genetics approach to generate a full-length reporter virus (YFVhb) by introducing a small HiBit tag in the NS1 protein. The reporter virus replicates at a similar rate to the parental YFV in HuH-7 cells. Using YFVhb, we designed a high throughput antiviral screening luciferase-based assay to identify inhibitors that target any step of the viral replication cycle. We validated our assay by using a range of inhibitors including drugs, immune sera and neutralizing single chain variable fragments (scFv). In light of the recent upsurge in YFV and a potential spread of the virus, this assay is a further tool in the development of antiviral therapy against YFV.
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http://dx.doi.org/10.1016/j.antiviral.2020.104939DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7649875PMC
November 2020

Population genomics of louping ill virus provide new insights into the evolution of tick-borne flaviviruses.

PLoS Negl Trop Dis 2020 09 14;14(9):e0008133. Epub 2020 Sep 14.

Institute of Biodiversity, Animal Health and Comparative Medicine - University of Glasgow, Glasgow, United Kingdom.

The emergence and spread of tick-borne arboviruses pose an increased challenge to human and animal health. In Europe this is demonstrated by the increasingly wide distribution of tick-borne encephalitis virus (TBEV, Flavivirus, Flaviviridae), which has recently been found in the United Kingdom (UK). However, much less is known about other tick-borne flaviviruses (TBFV), such as the closely related louping ill virus (LIV), an animal pathogen which is endemic to the UK and Ireland, but which has been detected in other parts of Europe including Scandinavia and Russia. The emergence and potential spatial overlap of these viruses necessitates improved understanding of LIV genomic diversity, geographic spread and evolutionary history. We sequenced a virus archive composed of 22 LIV isolates which had been sampled throughout the UK over a period of over 80 years. Combining this dataset with published virus sequences, we detected no sign of recombination and found low diversity and limited evidence for positive selection in the LIV genome. Phylogenetic analysis provided evidence of geographic clustering as well as long-distance movement, including movement events that appear recent. However, despite genomic data and an 80-year time span, we found that the data contained insufficient temporal signal to reliably estimate a molecular clock rate for LIV. Additional analyses revealed that this also applied to TBEV, albeit to a lesser extent, pointing to a general problem with phylogenetic dating for TBFV. The 22 LIV genomes generated during this study provide a more reliable LIV phylogeny, improving our knowledge of the evolution of tick-borne flaviviruses. Our inability to estimate a molecular clock rate for both LIV and TBEV suggests that temporal calibration of tick-borne flavivirus evolution should be interpreted with caution and highlight a unique aspect of these viruses which may be explained by their reliance on tick vectors.
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http://dx.doi.org/10.1371/journal.pntd.0008133DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7515184PMC
September 2020

Clinical and Laboratory Diagnosis of SARS-CoV-2, the Virus Causing COVID-19.

ACS Infect Dis 2020 09 20;6(9):2319-2336. Epub 2020 Aug 20.

Department of Virology, Aggeu Magalhães Institute (IAM), Oswaldo Cruz Foundation (Fiocruz), 50670-420, Recife, Pernambuco, Brazil.

In December 2019, a novel beta (β) coronavirus eventually named SARS-CoV-2 emerged in Wuhan, Hubei province, China, causing an outbreak of severe and even fatal pneumonia in humans. The virus has spread very rapidly to many countries across the world, resulting in the World Health Organization (WHO) to declare a pandemic on March 11, 2020. Clinically, the diagnosis of this unprecedented illness, called coronavirus disease-2019 (COVID-19), becomes difficult because it shares many symptoms with other respiratory pathogens, including influenza and parainfluenza viruses. Therefore, laboratory diagnosis is crucial for the clinical management of patients and the implementation of disease control strategies to contain SARS-CoV-2 at clinical and population level. Here, we summarize the main clinical and imaging findings of COVID-19 patients and discuss the advances, features, advantages, and limitations of different laboratory methods used for SARS-CoV-2 diagnosis.
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http://dx.doi.org/10.1021/acsinfecdis.0c00274DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7441751PMC
September 2020

aBravo Is a Novel Antiviral Protein that Interacts with, but Acts Independently of, the Exogenous siRNA Pathway Effector Dicer 2.

Viruses 2020 07 11;12(7). Epub 2020 Jul 11.

MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK.

Mosquitoes, such as , can transmit arboviruses to humans. The exogenous short interfering RNA (exo-siRNA) pathway plays a major antiviral role in controlling virus infection in mosquito cells. The Dicer 2 (Dcr2) nuclease is a key effector protein in this pathway, which cleaves viral double-stranded RNA into virus-derived siRNAs that are further loaded onto an effector called Argonaute 2 (Ago2), which as part of the multiprotein RNA-induced silencing complex (RISC) targets and cleaves viral RNA. In order to better understand the effector protein Dcr2, proteomics experiments were conducted to identify interacting cellular partners. We identified several known interacting partners including Ago2, as well as two novel and previously uncharacterized proteins. The role of these two proteins was further investigated, and their interactions with Dcr2 verified by co-immunoprecipitation. Interestingly, despite their ability to interact with Ago2 and Piwi4, neither of these proteins was found to affect exo-siRNA silencing in a reporter assay. However, one of these proteins, Q0IFK9, subsequently called aBravo (edine oadly active ntiiral prtein), was found to mediate antiviral activity against positive strand RNA arboviruses. Intriguingly the presence of Dcr2 was not necessary for this effect, suggesting that this interacting antiviral effector may act as part of protein complexes with potentially separate antiviral activities.
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http://dx.doi.org/10.3390/v12070748DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7411624PMC
July 2020

Insights into SARS-CoV-2, the Coronavirus Underlying COVID-19: Recent Genomic Data and the Development of Reverse Genetics Systems.

J Gen Virol 2020 10 24;101(10):1021-1024. Epub 2020 Jun 24.

Department of Virology, Aggeu Magalhães Institute (IAM), Oswaldo Cruz Foundation (Fiocruz), 50670-420, Recife Pernambuco, Brazil.

The emergence and rapid worldwide spread of a novel pandemic of acute respiratory disease - eventually named coronavirus disease 2019 (COVID-19) by the World Health Organization (WHO) - across the human population has raised great concerns. It prompted a mobilization around the globe to study the underlying pathogen, a close relative of severe acute respiratory syndrome coronavirus (SARS-CoV) called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Numerous genome sequences of SARS-CoV-2 are now available and in-depth analyses are advancing. These will allow detailed characterization of sequence and protein functions, including comparative studies. Care should be taken when inferring function from sequence information alone, and reverse genetics systems can be used to unequivocally identify key features. For example, the molecular markers of virulence, host range and transmissibility of SARS-CoV-2 can be compared to those of related viruses in order to shed light on the biology of this emerging pathogen. Here, we summarize some recent insights from genomic studies and strategies for reverse genetics systems to generate recombinant viruses, which will be useful to investigate viral genome properties and evolution.
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http://dx.doi.org/10.1099/jgv.0.001458DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7660456PMC
October 2020

RIG-I Plays a Dominant Role in the Induction of Transcriptional Changes in Zika Virus-Infected Cells, which Protect from Virus-Induced Cell Death.

Cells 2020 06 16;9(6). Epub 2020 Jun 16.

Medical Research Council Human Immunology Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK.

The Zika virus (ZIKV) has received much attention due to an alarming increase in cases of neurological disorders including congenital Zika syndrome associated with infection. To date, there is no effective treatment available. An immediate response by the innate immune system is crucial for effective control of the virus. Using CRISPR/Cas9-mediated knockouts in A549 cells, we investigated the individual contributions of the RIG-I-like receptors MDA5 and RIG-I to ZIKV sensing and control of this virus by using a Brazilian ZIKV strain. We show that RIG-I is the main sensor for ZIKV in A549 cells. Surprisingly, we observed that loss of RIG-I and consecutive type I interferon (IFN) production led to virus-induced apoptosis. ZIKV non-structural protein NS5 was reported to interfere with type I IFN receptor signaling. Additionally, we show that ZIKV NS5 inhibits type I IFN induction. Overall, our study highlights the importance of RIG-I-dependent ZIKV sensing for the prevention of virus-induced cell death and shows that NS5 inhibits the production of type I IFN.
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http://dx.doi.org/10.3390/cells9061476DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7349056PMC
June 2020

Glucose-Regulated Protein 78 Interacts with Zika Virus Envelope Protein and Contributes to a Productive Infection.

Viruses 2020 05 9;12(5). Epub 2020 May 9.

MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK.

Zika virus (ZIKV; Flaviviridae) is a mosquito-borne flavivirus shown to cause fetal abnormalities collectively known as congenital Zika syndrome and Guillain-Barré syndrome in recent outbreaks. Currently, there is no specific treatment or vaccine available, and more effort is needed to identify cellular factors in the viral life cycle. Here, we investigated interactors of ZIKV envelope (E) protein by combining protein pull-down with mass spectrometry. We found that E interacts with the endoplasmic reticulum (ER) resident chaperone, glucose regulated protein 78 (GRP78). Although other flaviviruses are known to co-opt ER resident proteins, including GRP78, to enhance viral infectivity, the role ER proteins play during the ZIKV life cycle is yet to be elucidated. We showed that GRP78 levels increased during ZIKV infection and localised to sites coincident with ZIKV E staining. Depletion of GRP78 using specific siRNAs significantly reduced reporter-virus luciferase readings, viral protein synthesis, and viral titres. Additionally, GRP78 depletion reduced the ability of ZIKV to disrupt host cell translation and altered the localisation of viral replication factories, though there was no effect on viral RNA synthesis. In summary, we showed GRP78 is a vital host-factor during ZIKV infection, which may be involved in the coordination of viral replication factories.
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http://dx.doi.org/10.3390/v12050524DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7290722PMC
May 2020

Identification and RNAi Profile of a Novel Iflavirus Infecting Senegalese Mosquitoes.

Viruses 2020 04 14;12(4). Epub 2020 Apr 14.

Institute for Parasitology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany.

The inland floodwater mosquito (Meigen, 1830) is a competent vector of numerous arthropod-borne viruses such as Rift Valley fever virus () and Zika virus (). spp. have widespread Afrotropical distribution and are common European cosmopolitan mosquitoes. We examined the virome of samples from Barkédji village, Senegal, with small RNA sequencing, bioinformatic analysis, and RT-PCR screening. We identified a novel 9494 nt iflavirus () designated here as Aedes vexans iflavirus (AvIFV). Annotation of the AvIFV genome reveals a 2782 amino acid polyprotein with iflavirus protein domain architecture and typical iflavirus 5' internal ribosomal entry site and 3' poly-A tail. Aedes vexans iflavirus is most closely related to a partial virus sequence from (a parasitoid wasp) with 56.77% pairwise amino acid identity. Analysis of AvIFV-derived small RNAs suggests that AvIFV is targeted by the exogenous RNA interference pathway but not the PIWI-interacting RNA response, as ~60% of AvIFV reads corresponded to 21 nt Dicer-2 virus-derived small RNAs and the 24-29 nt AvIFV read population did not exhibit a "ping-pong" signature. The RT-PCR screens of archival and current (circa 2011-2020) laboratory samples and wild-caught mosquitoes from Barkédji suggest that AvIFV is ubiquitous in these mosquitoes. Further, we screened wild-caught European samples from Germany, the United Kingdom, Italy, and Sweden, all of which tested negative for AvIFV RNA. This report provides insight into the diversity of commensal viruses and the host RNAi response towards iflaviruses.
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http://dx.doi.org/10.3390/v12040440DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7232509PMC
April 2020

Development of a Reverse Genetics System for Toscana Virus (Lineage A).

Viruses 2020 04 7;12(4). Epub 2020 Apr 7.

MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, Scotland, UK.

Toscana virus (TOSV) is a in the family, order , found in the countries surrounding the Mediterranean. TOSV is an important cause of seasonal acute meningitis and encephalitis within its range. Here, we determined the full sequence of the TOSV strain 1500590, a lineage A virus obtained from an infected patient (Marseille, 2007) and used this in combination with other sequence information to construct functional cDNA plasmids encoding the viral L, M, and S antigenomic sequences under the control of the T7 RNA promoter to recover recombinant viruses. Importantly, resequencing identified two single nucleotide changes to a TOSV reference genome, which, when corrected, restored functionality to the polymerase L and made it possible to recover infectious recombinant TOSV (rTOSV) from cDNA, as well as establish a minigenome system. Using reverse genetics, we produced an NSs-deletant rTOSV and also obtained viruses expressing reporter genes instead of NSs. The availability of such a system assists investigating questions that require genetic manipulation of the viral genome, such as investigations into replication and tropism, and beyond these fundamental aspects, also the development of novel vaccine design strategies.
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http://dx.doi.org/10.3390/v12040411DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7232365PMC
April 2020

The Aedes aegypti Domino Ortholog p400 Regulates Antiviral Exogenous Small Interfering RNA Pathway Activity and Expression.

mSphere 2020 04 8;5(2). Epub 2020 Apr 8.

MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland

Arboviruses are pathogens of humans and animals. A better understanding of the interactions between these pathogens and the arthropod vectors, such as mosquitoes, that transmit them is necessary to develop novel control measures. A major antiviral pathway in the mosquito vector is the exogenous small interfering RNA (exo-siRNA) pathway, which is induced by arbovirus-derived double-stranded RNA in infected cells. Although recent work has shown the key role played by Argonaute-2 (Ago-2) and Dicer-2 (Dcr-2) in this pathway, the regulatory mechanisms that govern these pathways have not been studied in mosquitoes. Here, we show that the Domino ortholog p400 has antiviral activity against the alphavirus Semliki Forest virus () both in -derived cells and Antiviral activity of p400 was also demonstrated against chikungunya virus () and Bunyamwera virus (e) but not Zika virus (). p400 was found to be expressed across mosquito tissues and regulated but not transcript levels in mosquitoes. These findings provide novel insights into the regulation of an important aedine exo-siRNA pathway effector protein, Ago-2, by the Domino ortholog p400. They add functional insights to previous observations of this protein's antiviral and RNA interference regulatory activities in Female mosquitoes are vectors of human-infecting arthropod-borne viruses (arboviruses). In recent decades, the incidence of arthropod-borne viral infections has grown dramatically. Vector competence is influenced by many factors, including the mosquito's antiviral defenses. The exogenous small interfering RNA (siRNA) pathway is a major antiviral response restricting arboviruses in mosquitoes. While the roles of the effectors of this pathway, Argonaute-2 and Dicer-2 are well characterized, nothing is known about its regulation in mosquitoes. In this study, we demonstrate that p400, whose ortholog Domino in is a chromatin-remodeling ATPase member of the Tip60 complex, regulates siRNA pathway activity and controls expression levels. In addition, we found p400 to have antiviral activity against different arboviruses. Therefore, our study provides new insights into the regulation of the antiviral response in mosquitoes.
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http://dx.doi.org/10.1128/mSphere.00081-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142294PMC
April 2020

The mosquito electrocuting trap as an exposure-free method for measuring human-biting rates by Aedes mosquito vectors.

Parasit Vectors 2020 Jan 15;13(1):31. Epub 2020 Jan 15.

Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.

Background: Entomological monitoring of Aedes vectors has largely relied on surveillance of larvae, pupae and non-host-seeking adults, which have been poorly correlated with human disease incidence. Exposure to mosquito-borne diseases can be more directly estimated using human landing catches (HLC), although this method is not recommended for Aedes-borne arboviruses. We evaluated a new method previously tested with malaria vectors, the mosquito electrocuting trap (MET) as an exposure-free alternative for measuring landing rates of Aedes mosquitoes on people. Aims were to (i) compare the MET to the BG-sentinel (BGS) trap gold standard approach for sampling host-seeking Aedes vectors; and (ii) characterize the diel activity of Aedes vectors and their association with microclimatic conditions.

Methods: The study was conducted over 12 days in Quinindé (Ecuador) in May 2017. Mosquito sampling stations were set up in the peridomestic area of four houses. On each day of sampling, each house was allocated either a MET or a BGS trap, which were rotated amongst the four houses daily in a Latin square design. Mosquito abundance and microclimatic conditions were recorded hourly at each sampling station between 7:00-19:00 h to assess variation between vector abundance, trapping methods, and environmental conditions. All Aedes aegypti females were tested for the presence of Zika (ZIKV), dengue (DENV) and chikungunya (CHIKV) viruses.

Results: A higher number of Ae. aegypti females were found in MET than in BGS collections, although no statistically significant differences in mean Ae. aegypti abundance between trapping methods were found. Both trapping methods indicated female Ae. aegypti had bimodal patterns of host-seeking, being highest during early morning and late afternoon hours. Mean Ae. aegypti daily abundance was negatively associated with daily temperature. No infection by ZIKV, DENV or CHIKV was detected in any Aedes mosquitoes caught by either trapping method.

Conclusion: We conclude the MET performs at least as well as the BGS standard and offers the additional advantage of direct measurement of per capita human-biting rates. If detection of arboviruses can be confirmed in MET-collected Aedes in future studies, this surveillance method could provide a valuable tool for surveillance and prediction on human arboviral exposure risk.
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http://dx.doi.org/10.1186/s13071-020-3887-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6961254PMC
January 2020

Tick-borne encephalitis virus inhibits rRNA synthesis and host protein production in human cells of neural origin.

PLoS Negl Trop Dis 2019 09 27;13(9):e0007745. Epub 2019 Sep 27.

Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic.

Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus (Flaviviridae), is a causative agent of a severe neuroinfection. Recently, several flaviviruses have been shown to interact with host protein synthesis. In order to determine whether TBEV interacts with this host process in its natural target cells, we analysed de novo protein synthesis in a human cell line derived from cerebellar medulloblastoma (DAOY HTB-186). We observed a significant decrease in the rate of host protein synthesis, including the housekeeping genes HPRT1 and GAPDH and the known interferon-stimulated gene viperin. In addition, TBEV infection resulted in a specific decrease of RNA polymerase I (POLR1) transcripts, 18S and 28S rRNAs and their precursor, 45-47S pre-rRNA, but had no effect on the POLR3 transcribed 5S rRNA levels. To our knowledge, this is the first report of flavivirus-induced decrease of specifically POLR1 rRNA transcripts accompanied by host translational shut-off.
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http://dx.doi.org/10.1371/journal.pntd.0007745DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6785130PMC
September 2019

Metaviromics Reveals Unknown Viral Diversity in the Biting Midge .

Viruses 2019 09 17;11(9). Epub 2019 Sep 17.

MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK.

Biting midges ( species) are vectors of arboviruses and were responsible for the emergence and spread of (SBV) in Europe in 2011 and are likely to be involved in the emergence of other arboviruses in Europe. Improved surveillance and better understanding of risks require a better understanding of the circulating viral diversity in these biting insects. In this study, we expand the sequence space of RNA viruses by identifying a number of novel RNA viruses from (biting midge) using a meta-transcriptomic approach. A novel metaviromic pipeline called MetaViC was developed specifically to identify novel virus sequence signatures from high throughput sequencing (HTS) datasets in the absence of a known host genome. MetaViC is a protein centric pipeline that looks for specific protein signatures in the reads and contigs generated as part of the pipeline. Several novel viruses, including an alphanodavirus with both segments, a novel relative of the Hubei sobemo-like virus 49, two rhabdo-like viruses and a chuvirus, were identified in the Scottish midge samples. The newly identified viruses were found to be phylogenetically distinct to those previous known. These findings expand our current knowledge of viral diversity in arthropods and especially in these understudied disease vectors.
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http://dx.doi.org/10.3390/v11090865DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6784199PMC
September 2019

The Transcriptional and Protein Profile From Human Infected Neuroprogenitor Cells Is Strongly Correlated to Zika Virus Microcephaly Cytokines Phenotype Evidencing a Persistent Inflammation in the CNS.

Front Immunol 2019 16;10:1928. Epub 2019 Aug 16.

Oswaldo Cruz Foundation/Fiocruz, Institute Aggeu Magalhães, Recife, Brazil.

Zika virus (ZIKV) infection during pregnancy is associated with microcephaly, a congenital malformation resulting from neuroinflammation and direct effects of virus replication on the developing central nervous system (CNS). However, the exact changes in the affected CNS remain unknown. Here, we show by transcriptome analysis (at 48 h post-infection) and multiplex immune profiling that human induced-neuroprogenitor stem cells (hiNPCs) respond to ZIKV infection with a strong induction of type-I interferons (IFNs) and several type-I IFNs stimulated genes (ISGs), notably cytokines and the pro-apoptotic chemokines CXCL9 and CXCL10. By comparing the inflammatory profile induced by a ZIKV Brazilian strain with an ancestral strain isolated from Cambodia in 2010, we observed that the response magnitude differs among them. Compared to ZIKV/Cambodia, the experimental infection of hiNPCs with ZIKV/Brazil resulted in a diminished induction of ISGs and lower induction of several cytokines (IFN-α, IL-1α/β, IL-6, IL-8, and IL-15), consequently favoring virus replication. From ZIKV-confirmed infant microcephaly cases, we detected a similar profile characterized by the presence of IFN-α, CXCL10, and CXCL9 in cerebrospinal fluid (CSF) samples collected after birth, evidencing a sustained CNS inflammation. Altogether, our data suggest that the CNS may be directly affected due to an unbalanced and chronic local inflammatory response, elicited by ZIKV infection, which contributes to damage to the fetal brain.
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http://dx.doi.org/10.3389/fimmu.2019.01928DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6707094PMC
October 2020

Infection and transmission of Cache Valley virus by Aedes albopictus and Aedes aegypti mosquitoes.

Parasit Vectors 2019 Jul 31;12(1):384. Epub 2019 Jul 31.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, 66506, USA.

Background: Cache Valley virus (CVV; Bunyavirales, Peribunyaviridae) is a mosquito-borne arbovirus endemic in North America. Although severe diseases are mainly observed in pregnant ruminants, CVV has also been recognized as a zoonotic pathogen that can cause fatal encephalitis in humans. Human exposures to CVV and its related subtypes occur frequently under different ecological conditions in the New World; however, neurotropic disease is rarely reported. High prevalence rates of neutralizing antibodies have been detected among residents in several Latin American cities. However, zoophilic mosquito species involved in the enzootic transmission are unlikely to be responsible for the transmission leading to human exposures to CVV. Mechanisms that lead to frequent human exposures to CVV remain largely unknown. In this study, competence of two anthropophilic mosquitoes, Aedes albopictus and Ae. aegypti, for CVV was determined using per os infection to determine if these species could play a role in the transmission of CVV in the domestic and peridomestic settings of urban and suburban areas.

Results: Aedes albopictus were highly susceptible to CVV whereas infection of Ae. aegypti occurred at a significantly lower frequency. Whilst the dissemination rates of CVV were comparable in the two species, the relatively long period to attain maximal infectious titer in Ae. aegypti demonstrated a significant difference in the replication kinetics of CVV in these species. Detection of viral RNA in saliva suggests that both Ae. albopictus and Ae. aegypti are competent vectors for CVV under laboratory conditions.

Conclusions: Differential susceptibility to CVV was observed in Ae. albopictus and Ae. aegypti, reflecting their relatively different capacities for vectoring CVV in nature. The high susceptibility of Ae. albopictus to CVV observed in this study suggests its potential role as an efficient vector for CVV. Complemented by the reports of multiple CVV isolates derived from Ae. albopictus, our finding provides the basis for how the dispersal of Ae. albopictus across the New World may have a significant impact on the transmission and ecology of CVV.
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http://dx.doi.org/10.1186/s13071-019-3643-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6670168PMC
July 2019

Structural and phenotypic analysis of Chikungunya virus RNA replication elements.

Nucleic Acids Res 2019 09;47(17):9296-9312

School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK.

Chikungunya virus (CHIKV) is a re-emerging, pathogenic Alphavirus transmitted to humans by Aedes spp. mosquitoes. We have mapped the RNA structure of the 5' region of the CHIKV genome using selective 2'-hydroxyl acylation analysed by primer extension (SHAPE) to investigate intramolecular base-pairing at single-nucleotide resolution. Taking a structure-led reverse genetic approach, in both infectious virus and sub-genomic replicon systems, we identified six RNA replication elements essential to efficient CHIKV genome replication - including novel elements, either not previously analysed in other alphaviruses or specific to CHIKV. Importantly, through a reverse genetic approach we demonstrate that the replication elements function within the positive-strand genomic copy of the virus genome, in predominantly structure-dependent mechanisms during efficient replication of the CHIKV genome. Comparative analysis in human and mosquito-derived cell lines reveal that a novel element within the 5'UTR is essential for efficient replication in both host systems, while those in the adjacent nsP1 encoding region are specific to either vertebrate or invertebrate host cells. In addition to furthering our knowledge of fundamental aspects of the molecular virology of this important human pathogen, we foresee that results from this study will be important for rational design of a genetically stable attenuated vaccine.
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http://dx.doi.org/10.1093/nar/gkz640DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6753490PMC
September 2019

Assessing the Potential Interactions between Cellular miRNA and Arboviral Genomic RNA in the Yellow Fever Mosquito, .

Viruses 2019 06 10;11(6). Epub 2019 Jun 10.

Unit of Arboviruses and Insect Vectors, Department of Virology, Institut Pasteur, 75015 Paris, France.

Although the role of exogenous small interfering RNA (siRNA) and P-element induced wimpy testis (PIWI)-interacting RNA (piRNA) pathways in mosquito antiviral immunity is increasingly better understood, there is still little knowledge regarding the role of mosquito cellular microRNA (miRNA). Identifying direct interactions between the mosquito miRNAs and the RNA genome of arboviruses and choosing the relevant miRNA candidates to explore resulting antiviral mechanisms are critical. Here, we carried out genomic analyses to identify miRNAs that potentially interact with various lineages and genotypes of chikungunya, dengue, and Zika viruses. By using prediction tools with distinct algorithms, several miRNA binding sites were commonly found within different genotypes/and or lineages of each arbovirus. We further analyzed those miRNAs that could target more than one arbovirus, required a low energy threshold to form miRNA-viralRNA (vRNA) complexes, and predicted potential RNA structures using RNAhybrid software. We predicted miRNA candidates that might participate in regulating arboviral replication in . Even without any experimental validation, which should be done as a next step, this study can shed further light on the role of miRNA in mosquito innate immunity and targets for future studies.
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http://dx.doi.org/10.3390/v11060540DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6631873PMC
June 2019

The circadian clock components BMAL1 and REV-ERBα regulate flavivirus replication.

Nat Commun 2019 01 22;10(1):377. Epub 2019 Jan 22.

Nuffield Department of Medicine, University of Oxford, Oxford OX3 7FZ, UK.

The circadian clock regulates immune responses to microbes and affects pathogen replication, but the underlying molecular mechanisms are not well understood. Here we demonstrate that the circadian components BMAL1 and REV-ERBα influence several steps in the hepatitis C virus (HCV) life cycle, including particle entry into hepatocytes and RNA genome replication. Genetic knock out of Bmal1 and over-expression or activation of REV-ERB with synthetic agonists inhibits the replication of HCV and the related flaviruses dengue and Zika via perturbation of lipid signaling pathways. This study highlights a role for the circadian clock component REV-ERBα in regulating flavivirus replication.
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http://dx.doi.org/10.1038/s41467-019-08299-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6343007PMC
January 2019

M Segment-Based Minigenomes and Virus-Like Particle Assays as an Approach To Assess the Potential of Tick-Borne Genome Reassortment.

J Virol 2019 03 5;93(6). Epub 2019 Mar 5.

MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom

Bunyaviruses have a tripartite negative-sense RNA genome. Due to the segmented nature of these viruses, if two closely related viruses coinfect the same host or vector cell, it is possible that RNA segments from either of the two parental viruses will be incorporated into progeny virions to give reassortant viruses. Little is known about the ability of tick-borne phleboviruses to reassort. The present study describes the development of minigenome assays for the tick-borne viruses Uukuniemi phlebovirus (UUKV) and Heartland phlebovirus (HRTV). We used these minigenome assays in conjunction with the existing minigenome system of severe fever with thrombocytopenia syndrome (SFTS) phlebovirus (SFTSV) to assess the abilities of viral N and L proteins to recognize, transcribe, and replicate the M segment-based minigenome of a heterologous virus. The highest minigenome activity was detected with the M segment-based minigenomes of cognate viruses. However, our findings indicate that several combinations utilizing N and L proteins of heterologous viruses resulted in M segment minigenome activity. This suggests that the M segment untranslated regions (UTRs) are recognized as functional promoters of transcription and replication by the N and L proteins of related viruses. Further, virus-like particle assays demonstrated that HRTV glycoproteins can package UUKV and SFTSV S and L segment-based minigenomes. Taken together, these results suggest that coinfection with these viruses could lead to the generation of viable reassortant progeny. Thus, the tools developed in this study could aid in understanding the role of genome reassortment in the evolution of these emerging pathogens in an experimental setting. In recent years, there has been a large expansion in the number of emerging tick-borne viruses that are assigned to the genus. Bunyaviruses have a tripartite segmented genome, and infection of the same host cell by two closely related bunyaviruses can, in theory, result in eight progeny viruses with different genome segment combinations. We used genome analogues expressing reporter genes to assess the abilities of nucleocapsid protein and RNA-dependent RNA polymerase to recognize the untranslated region of a genome segment of a related phlebovirus, and we used virus-like particle assays to assess whether viral glycoproteins can package genome analogues of related phleboviruses. Our results provide strong evidence that these emerging pathogens could reassort their genomes if they were to meet in nature in an infected host or vector. This reassortment process could result in viruses with new pathogenic properties.
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http://dx.doi.org/10.1128/JVI.02068-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6401446PMC
March 2019

Antiviral RNA Interference Activity in Cells of the Predatory Mosquito, .

Viruses 2018 12 6;10(12). Epub 2018 Dec 6.

MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland G61 1QH, UK.

Arthropod vectors control the replication of arboviruses through their innate antiviral immune responses. In particular, the RNA interference (RNAi) pathways are of notable significance for the control of viral infections. Although much has been done to understand the role of RNAi in vector populations, little is known about its importance in non-vector mosquito species. In this study, we investigated the presence of an RNAi response in , which is a non-blood feeding species proposed as a biological control agent against pest mosquitoes. Using a derived cell line (TRA-171), we demonstrate that these mosquitoes possess a functional RNAi response that is active against a mosquito-borne alphavirus, Semliki Forest virus. As observed in vector mosquito species, small RNAs are produced that target viral sequences. The size and characteristics of these small RNAs indicate that both the siRNA and piRNA pathways are induced in response to infection. Taken together, this data suggests that are able to control viral infections in a similar way to natural arbovirus vector mosquito species. Understanding their ability to manage arboviral infections will be advantageous when assessing these and similar species as biological control agents.
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http://dx.doi.org/10.3390/v10120694DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6316411PMC
December 2018

Revisiting Key Entry Routes of Human Epidemic Arboviruses into the Mainland Americas through Large-Scale Phylogenomics.

Int J Genomics 2018 8;2018:6941735. Epub 2018 Oct 8.

Department of Virology, Aggeu Magalhães Institute (IAM), Oswaldo Cruz Foundation (FIOCRUZ), Recife PE, Brazil.

The rapid worldwide spread of chikungunya (CHIKV), dengue (DENV), and Zika (ZIKV) viruses have raised great international concern. Knowledge about the entry routes and geographic expansion of these arboviruses to the mainland Americas remain incomplete and controversial. Epidemics caused by arboviruses continue to cause socioeconomic burden globally, particularly in countries where vector control is difficult due to climatic or infrastructure factors. Understanding how the virus circulates and moves from one country to another is of paramount importance to assist government and health officials in anticipating future epidemics, as well as to take steps to help control or mitigate the spread of the virus. Through the analyses of the sequences of arbovirus genomes collected at different locations over time, we identified patterns of accumulated mutations, being able to trace routes of dispersion of these viruses. Here, we applied robust phylogenomic methods to trace the evolutionary dynamics of these arboviruses with special focus on Brazil, the epicenter of these triple epidemics. Our results show that CHIKV, DENV-1-4, and ZIKV followed a similar path prior to their first introductions into the mainland Americas, underscoring the need for systematic arboviral surveillance at major entry points of human population movement between countries such as airports and seaports.
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http://dx.doi.org/10.1155/2018/6941735DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6196792PMC
October 2018