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Ortolá B, Daròs JA. RNA Interference in Insects: From a Natural Mechanism of Gene Expression Regulation to a Biotechnological Crop Protection Promise. BIOLOGY 2024; 13:137. [PMID: 38534407 DOI: 10.3390/biology13030137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/14/2024] [Accepted: 02/19/2024] [Indexed: 03/28/2024]
Abstract
Insect pests rank among the major limiting factors in agricultural production worldwide. In addition to direct effect on crops, some phytophagous insects are efficient vectors for plant disease transmission. Large amounts of conventional insecticides are required to secure food production worldwide, with a high impact on the economy and environment, particularly when beneficial insects are also affected by chemicals that frequently lack the desired specificity. RNA interference (RNAi) is a natural mechanism gene expression regulation and protection against exogenous and endogenous genetic elements present in most eukaryotes, including insects. Molecules of double-stranded RNA (dsRNA) or highly structured RNA are the substrates of cellular enzymes to produce several types of small RNAs (sRNAs), which play a crucial role in targeting sequences for transcriptional or post-transcriptional gene silencing. The relatively simple rules that underlie RNAi regulation, mainly based in Watson-Crick complementarity, have facilitated biotechnological applications based on these cellular mechanisms. This includes the promise of using engineered dsRNA molecules, either endogenously produced in crop plants or exogenously synthesized and applied onto crops, as a new generation of highly specific, sustainable, and environmentally friendly insecticides. Fueled on this expectation, this article reviews current knowledge about the RNAi pathways in insects, and some other applied questions such as production and delivery of recombinant RNA, which are critical to establish RNAi as a reliable technology for insect control in crop plants.
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Affiliation(s)
- Beltrán Ortolá
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universitat Politècnica de València, 46022 Valencia, Spain
| | - José-Antonio Daròs
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universitat Politècnica de València, 46022 Valencia, Spain
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Agboli E, Schulze J, Jansen S, Cadar D, Sreenu VB, Leggewie M, Altinli M, Badusche M, Jöst H, Börstler J, Schmidt-Chanasit J, Schnettler E. Interaction of Mesonivirus and Negevirus with arboviruses and the RNAi response in Culex tarsalis-derived cells. Parasit Vectors 2023; 16:361. [PMID: 37833743 PMCID: PMC10576325 DOI: 10.1186/s13071-023-05985-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 09/26/2023] [Indexed: 10/15/2023] Open
Abstract
BACKGROUND Mosquito-specific viruses (MSVs) comprise a variety of different virus families, some of which are known to interfere with infections of medically important arboviruses. Viruses belonging to the family Mesoniviridae or taxon Negevirus harbor several insect-specific viruses, including MSVs, which are known for their wide geographical distribution and extensive host ranges. Although these viruses are regularly identified in mosquitoes all over the world, their presence in mosquitoes in Germany had not yet been reported. METHODS A mix of three MSVs (Yichang virus [Mesoniviridae] and two negeviruses [Daeseongdong virus and Dezidougou virus]) in a sample that contained a pool of Coquillettidia richiardii mosquitoes collected in Germany was used to investigate the interaction of these viruses with different arboviruses in Culex-derived cells. In addition, small RNA sequencing and analysis of different mosquito-derived cells infected with this MSV mix were performed. RESULTS A strain of Yichang virus (Mesoniviridae) and two negeviruses (Daeseongdong virus and Dezidougou virus) were identified in the Cq. richiardii mosquitoes sampled in Germany, expanding current knowledge of their circulation in central Europe. Infection of mosquito-derived cells with these three viruses revealed that they are targeted by the small interfering RNA (siRNA) pathway. In Culex-derived cells, co-infection by these three viruses had varying effects on the representative arboviruses from different virus families (Togaviridae: Semliki forest virus [SFV]; Bunyavirales: Bunyamwera orthobunyavirus [BUNV]; or Flaviviridae: Usutu virus [USUV]). Specifically, persistent MSV co-infection inhibited BUNV infection, as well as USUV infection (but the latter only at specific time points). However, the impact on SFV infection was only noticeable at low multiplicity of infection (MOI 0.1) and at specific time points in combination with the infection status. CONCLUSIONS Taken together, these results are important findings that will lead to a better understanding of the complex interactions of MSVs, mosquitoes and arboviruses.
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Affiliation(s)
- Eric Agboli
- Bernhard-Nocht-Institute for Tropical Medicine, 20359, Hamburg, Germany
- School of Basic and Biomedical Sciences, Department of Biomedical Sciences, University of Health and Allied Sciences, PMB 31, Ho, Ghana
| | - Jonny Schulze
- Bernhard-Nocht-Institute for Tropical Medicine, 20359, Hamburg, Germany
| | - Stephanie Jansen
- Bernhard-Nocht-Institute for Tropical Medicine, 20359, Hamburg, Germany
- Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, 20148, Hamburg, Germany
| | - Daniel Cadar
- Bernhard-Nocht-Institute for Tropical Medicine, 20359, Hamburg, Germany
| | | | - Mayke Leggewie
- Bernhard-Nocht-Institute for Tropical Medicine, 20359, Hamburg, Germany
| | - Mine Altinli
- Bernhard-Nocht-Institute for Tropical Medicine, 20359, Hamburg, Germany
| | - Marlis Badusche
- Bernhard-Nocht-Institute for Tropical Medicine, 20359, Hamburg, Germany
| | - Hanna Jöst
- Bernhard-Nocht-Institute for Tropical Medicine, 20359, Hamburg, Germany
| | - Jessica Börstler
- Bernhard-Nocht-Institute for Tropical Medicine, 20359, Hamburg, Germany
| | - Jonas Schmidt-Chanasit
- Bernhard-Nocht-Institute for Tropical Medicine, 20359, Hamburg, Germany
- Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, 20148, Hamburg, Germany
| | - Esther Schnettler
- Bernhard-Nocht-Institute for Tropical Medicine, 20359, Hamburg, Germany.
- Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, 20148, Hamburg, Germany.
- German Center for Infection Research (DZIF), Partner Site Hamburg-Luebeck-Borstel-Riems, Hamburg, Germany.
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Leggewie M, Scherer C, Altinli M, Gestuveo RJ, Sreenu VB, Fuss J, Vazeille M, Mousson L, Badusche M, Kohl A, Failloux AB, Schnettler E. The Aedes aegypti RNA interference response against Zika virus in the context of co-infection with dengue and chikungunya viruses. PLoS Negl Trop Dis 2023; 17:e0011456. [PMID: 37440582 DOI: 10.1371/journal.pntd.0011456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 06/12/2023] [Indexed: 07/15/2023] Open
Abstract
Since its detection in 2015 in Brazil, Zika virus (ZIKV) has remained in the spotlight of international public health and research as an emerging arboviral pathogen. In addition to single infection, ZIKV may occur in co-infection with dengue (DENV) and chikungunya (CHIKV) viruses, with whom ZIKV shares geographic distribution and the mosquito Aedes aegypti as a vector. The main mosquito immune response against arboviruses is RNA interference (RNAi). It is unknown whether or not the dynamics of the RNAi response differ between single arboviral infections and co-infections. In this study, we investigated the interaction of ZIKV and DENV, as well as ZIKV and CHIKV co-infections with the RNAi response in Ae. aegypti. Using small RNA sequencing, we found that the efficiency of small RNA production against ZIKV -a hallmark of antiviral RNAi-was mostly similar when comparing single and co-infections with either DENV or CHIKV. Silencing of key antiviral RNAi proteins, showed no change in effect on ZIKV replication when the cell is co-infected with ZIKV and DENV or CHIKV. Interestingly, we observed a negative effect on ZIKV replication during CHIKV co-infection in the context of Ago2-knockout cells, though his effect was absent during DENV co-infection. Overall, this study provides evidence that ZIKV single or co-infections with CHIKV or DENV are equally controlled by RNAi responses. Thus, Ae. aegypti mosquitoes and derived cells support co-infections of ZIKV with either CHIKV or DENV to a similar level than single infections, as long as the RNAi response is functional.
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Affiliation(s)
- Mayke Leggewie
- Bernhard-Nocht Institute for Tropical Medicine, Hamburg, Germany
- German Center for Infection; Research (DZIF), partner site Hamburg-Luebeck-Borstel-Riems, Germany
| | - Christina Scherer
- Bernhard-Nocht Institute for Tropical Medicine, Hamburg, Germany
- German Center for Infection; Research (DZIF), partner site Hamburg-Luebeck-Borstel-Riems, Germany
| | - Mine Altinli
- Bernhard-Nocht Institute for Tropical Medicine, Hamburg, Germany
- German Center for Infection; Research (DZIF), partner site Hamburg-Luebeck-Borstel-Riems, Germany
| | - Rommel J Gestuveo
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
- Division of Biological Sciences, University of the Philippines Visayas, Miagao, Iloilo, Philippines
| | - Vattipally B Sreenu
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Janina Fuss
- Institute of Clinical Molecular Biology (IKMB), Kiel University, Kiel, Germany
| | - Marie Vazeille
- Institut Pasteur, Université Paris Cité, Arboviruses and Insect Vectors, Paris, France
| | - Laurence Mousson
- Institut Pasteur, Université Paris Cité, Arboviruses and Insect Vectors, Paris, France
| | - Marlis Badusche
- Bernhard-Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Anna-Bella Failloux
- Institut Pasteur, Université Paris Cité, Arboviruses and Insect Vectors, Paris, France
| | - Esther Schnettler
- Bernhard-Nocht Institute for Tropical Medicine, Hamburg, Germany
- German Center for Infection; Research (DZIF), partner site Hamburg-Luebeck-Borstel-Riems, Germany
- University Hamburg, Faculty of Mathematics, Informatics and Natural Sciences, Hamburg, Germany
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Laureti M, Lee RX, Bennett A, Wilson LA, Sy VE, Kohl A, Dietrich I. Rift Valley Fever Virus Primes Immune Responses in Aedes aegypti Cells. Pathogens 2023; 12:563. [PMID: 37111448 PMCID: PMC10146816 DOI: 10.3390/pathogens12040563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 03/25/2023] [Accepted: 04/03/2023] [Indexed: 04/29/2023] Open
Abstract
The ongoing global emergence of arthropod-borne (arbo) viruses has accelerated research into the interactions of these viruses with the immune systems of their vectors. Only limited information exists on how bunyaviruses, such as Rift Valley fever virus (RVFV), are sensed by mosquito immunity or escape detection. RVFV is a zoonotic phlebovirus (Bunyavirales; Phenuiviridae) of veterinary and human public health and economic importance. We have shown that the infection of mosquitoes with RVFV triggers the activation of RNA interference pathways, which moderately restrict viral replication. Here, we aimed to better understand the interactions between RVFV and other vector immune signaling pathways that might influence RVFV replication and transmission. For this, we used the immunocompetent Aedes aegypti Aag2 cell line as a model. We found that bacteria-induced immune responses restricted RVFV replication. However, virus infection alone did not alter the gene expression levels of immune effectors. Instead, it resulted in the marked enhancement of immune responses to subsequent bacterial stimulation. The gene expression levels of several mosquito immune pattern recognition receptors were altered by RVFV infection, which may contribute to this immune priming. Our findings imply that there is a complex interplay between RVFV and mosquito immunity that could be targeted in disease prevention strategies.
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Affiliation(s)
| | - Rui-Xue Lee
- MRC-University of Glasgow Centre for Virus Research, 464 Bearsden Road, Glasgow G61 1QH, UK
| | - Amelia Bennett
- The Pirbright Institute, Ash Road, Pirbright GU24 0NF, UK
- Department of Life Sciences, Faculty of Science, Claverton Down, University of Bath, Bath BA2 7AY, UK
| | - Lucas Aladar Wilson
- The Pirbright Institute, Ash Road, Pirbright GU24 0NF, UK
- Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, Foresterhill, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | | | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, 464 Bearsden Road, Glasgow G61 1QH, UK
| | - Isabelle Dietrich
- The Pirbright Institute, Ash Road, Pirbright GU24 0NF, UK
- MRC-University of Glasgow Centre for Virus Research, 464 Bearsden Road, Glasgow G61 1QH, UK
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Antiviral RNAi Response in Culex quinquefasciatus-Derived HSU Cells. Viruses 2023; 15:v15020436. [PMID: 36851650 PMCID: PMC9968050 DOI: 10.3390/v15020436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 01/20/2023] [Accepted: 01/31/2023] [Indexed: 02/09/2023] Open
Abstract
Culex spp. mosquitoes are important vectors of viruses, such as West Nile virus, Eastern equine encephalitis virus and Rift valley fever virus. However, their interactions with innate antiviral immunity, especially RNA interference (RNAi), are not well known. Most research on RNAi pathways in mosquitoes is focused on the tropical vector mosquito Aedes aegypti. Here, we investigated the production of arbovirus-specific small RNAs in Cx. quinquefasciatus-derived HSU cells. Furthermore, by silencing RNAi-related proteins, we investigated the antiviral role of these proteins for two different arboviruses: Semliki Forest virus (SFV) and Bunyamwera orthobunyavirus (BUNV). Our results showed an expansion of Ago2 and Piwi6 in Cx. quinquefasciatus compared to Ae. aegypti. While silencing Ago2a and Ago2b increased BUNV replication, only Ago2b showed antiviral activity against SFV. Our results suggest differences in the function of Cx. quinquefasciatus and Ae. aegypti RNAi proteins and highlight the virus-specific function of these proteins in Cx. quinquefasciatus.
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Culex Mosquito Piwi4 Is Antiviral against Two Negative-Sense RNA Viruses. Viruses 2022; 14:v14122758. [PMID: 36560761 PMCID: PMC9781653 DOI: 10.3390/v14122758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/06/2022] [Accepted: 12/07/2022] [Indexed: 12/14/2022] Open
Abstract
Culex spp. mosquitoes transmit several pathogens concerning public health, including West Nile virus and Saint Louis encephalitis virus. Understanding the antiviral immune system of Culex spp. mosquitoes is important for reducing the transmission of these viruses. Mosquitoes rely on RNA interference (RNAi) to control viral replication. While the siRNA pathway in mosquitoes is heavily studied, less is known about the piRNA pathway. The piRNA pathway in mosquitoes has recently been connected to mosquito antiviral immunity. In Aedes aegypti, Piwi4 has been implicated in antiviral responses. The antiviral role of the piRNA pathway in Culex spp. mosquitoes is understudied compared to Ae. aegypti. Here, we aimed to identify the role of PIWI genes and piRNAs in Culex quinquefasciatus and Culex tarsalis cells during virus infection. We examined the effect of PIWI gene silencing on virus replication of two arboviruses and three insect-specific viruses in Cx. quinquefasciatus derived cells (Hsu) and Cx. tarsalis derived (CT) cells. We show that Piwi4 is antiviral against the La Crosse orthobunyavirus (LACV) in Hsu and CT cells, and the insect-specific rhabdovirus Merida virus (MERDV) in Hsu cells. None of the silenced PIWI genes impacted replication of the two flaviviruses Usutu virus (USUV) and Calbertado virus, or the phasivirus Phasi-Charoen-like virus. We further used small RNA sequencing to determine that LACV-derived piRNAs, but not USUV-derived piRNAs were generated in Hsu cells and that PIWI gene silencing resulted in a small reduction in vpiRNAs. Finally, we determined that LACV-derived DNA was produced in Hsu cells during infection, but whether this viral DNA is required for vpiRNA production remains unclear. Overall, we expanded our knowledge on the piRNA pathway and how it relates to the antiviral response in Culex spp mosquitoes.
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Sacbrood Virus: A Growing Threat to Honeybees and Wild Pollinators. Viruses 2022; 14:v14091871. [PMID: 36146677 PMCID: PMC9505205 DOI: 10.3390/v14091871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 08/19/2022] [Accepted: 08/22/2022] [Indexed: 11/17/2022] Open
Abstract
Sacbrood virus (SBV) is one of the many viruses that infect both the Western honeybee (Apis mellifera) and the Eastern honeybee (Apis cerana). Recently, the interspecies transmission of SBV has been discovered, especially among wild pollinators. This newly discovered evolutionary occurrence regarding SBV indicates a much wider host range than previously believed, causing further concern about the future sustainability of agriculture and the resilience of ecosystems. Over the past few decades, vast numbers of studies have been undertaken concerning SBV infection in honeybees, and remarkable progress has been made in our understanding of the epidemiology, pathogenesis, transmission, and manifestations of SBV infection in honeybees and other pollinators. Meanwhile, some methods, including Chinese medicine, have been established to control and prevent sacbrood disease in A. cerana in Asian countries. In this review, we summarize the existing knowledge of SBV and address the gaps in the knowledge within the existing literature in the hope of providing future directions for the research and development of management strategies for controlling the spread of this deadly disease.
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Antiviral RNAi Response against the Insect-Specific Agua Salud Alphavirus. mSphere 2022; 7:e0100321. [PMID: 35171691 PMCID: PMC8849343 DOI: 10.1128/msphere.01003-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Arboviruses transmitted by mosquitoes are responsible for the death of millions of people each year. In addition to arboviruses, many insect-specific viruses (ISVs) have been discovered in mosquitoes in the last decade. ISVs, in contrast to arboviruses transmitted by mosquitoes to vertebrates, cannot replicate in vertebrate cells even when they are evolutionarily closely related to arboviruses. The alphavirus genus includes many arboviruses, although only a few ISVs have been discovered from this genus so far. Here, we investigate the interactions of a recently isolated insect-specific alphavirus, Agua Salud alphavirus (ASALV), with its mosquito host. RNA interference (RNAi) is one of the essential antiviral responses against arboviruses, although there is little knowledge on the interactions of RNAi with ISVs. Through the knockdown of transcripts of the different key RNAi pathway (small interfering RNA [siRNA], microRNA [miRNA], and P-element-induced wimpy testis [PIWI]-interacting RNA [piRNA]) proteins, we show the antiviral role of Ago2 (siRNA), Ago1 (miRNA), and Piwi4 proteins against ASALV in Aedes aegypti-derived cells. ASALV replication was increased in Dicer2 and Ago2 knockout cells, confirming the antiviral role of the siRNA pathway. In infected cells, mainly ASALV-specific siRNAs are produced, while piRNA-like small RNAs, with the characteristic nucleotide bias resulting from ping-pong amplification, are produced only in Dicer2 knockout cells. Taken together, ASALV interactions with the mosquito RNAi response differ from those of arthropod-borne alphaviruses in some aspects, although they also share some commonalities. Further research is needed to understand whether the identified differences can be generalized to other insect-specific alphaviruses. IMPORTANCE Mosquitoes are efficient vectors for many arboviruses that cause emergent infectious diseases in humans. Many insect-specific viruses (ISVs) that can infect mosquitoes but cannot infect vertebrates have been discovered in the last decade. ISVs have attracted great attention due to their potential use in mosquito or arbovirus control, by either decreasing mosquito fitness or restricting arbovirus replication and transmission to humans. However, ISV-mosquito interactions are not well understood. RNA interference (RNAi) is the most important innate immune response against many arboviruses, while it is unknown if it is antiviral against ISVs. Here, we investigate in detail the antiviral effect of the RNAi response in mosquitoes against an ISV for the first time. Using a recently isolated insect-specific alphavirus, we show that the regulation of virus replication was different from that for arthropod-borne alphaviruses despite some similarities. The differences in mosquito-virus interactions could drive the different transmission modes, which could eventually drive the evolution of arboviruses. Hence, an understanding of mosquito-ISV interactions can shed light on the ecology and evolution of both ISVs and the medically important arboviruses.
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Öhlund P, Hayer J, Hesson JC, Blomström AL. Small RNA Response to Infection of the Insect-Specific Lammi Virus and Hanko Virus in an Aedes albopictus Cell Line. Viruses 2021; 13:v13112181. [PMID: 34834988 PMCID: PMC8620693 DOI: 10.3390/v13112181] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 10/26/2021] [Accepted: 10/27/2021] [Indexed: 12/11/2022] Open
Abstract
RNA interference (RNAi)-mediated antiviral immunity is believed to be the primary defense against viral infection in mosquitoes. The production of virus-specific small RNA has been demonstrated in mosquitoes and mosquito-derived cell lines for viruses in all of the major arbovirus families. However, many if not all mosquitoes are infected with a group of viruses known as insect-specific viruses (ISVs), and little is known about the mosquito immune response to this group of viruses. Therefore, in this study, we sequenced small RNA from an Aedes albopictus-derived cell line infected with either Lammi virus (LamV) or Hanko virus (HakV). These viruses belong to two distinct phylogenetic groups of insect-specific flaviviruses (ISFVs). The results revealed that both viruses elicited a strong virus-derived small interfering RNA (vsiRNA) response that increased over time and that targeted the whole viral genome, with a few predominant hotspots observed. Furthermore, only the LamV-infected cells produced virus-derived Piwi-like RNAs (vpiRNAs); however, they were mainly derived from the antisense genome and did not show the typical ping-pong signatures. HakV, which is more distantly related to the dual-host flaviviruses than LamV, may lack certain unknown sequence elements or structures required for vpiRNA production. Our findings increase the understanding of mosquito innate immunity and ISFVs' effects on their host.
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Affiliation(s)
- Pontus Öhlund
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7028, 750 07 Uppsala, Sweden;
- Correspondence: ; Tel.: +46-18-672-409
| | - Juliette Hayer
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, SLU-Global Bioinformatics Centre, P.O. Box 7023, 750 07 Uppsala, Sweden;
| | - Jenny C. Hesson
- Department of Medical Biochemistry and Microbiology, Zoonosis Science Center, Uppsala University, P.O. Box 582, 751 23 Uppsala, Sweden;
| | - Anne-Lie Blomström
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7028, 750 07 Uppsala, Sweden;
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An Aedes aegypti-Derived Ago2 Knockout Cell Line to Investigate Arbovirus Infections. Viruses 2021; 13:v13061066. [PMID: 34205194 PMCID: PMC8227176 DOI: 10.3390/v13061066] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/19/2021] [Accepted: 05/30/2021] [Indexed: 11/19/2022] Open
Abstract
Mosquitoes are known as important vectors of many arthropod-borne (arbo)viruses causing disease in humans. These include dengue (DENV) and Zika (ZIKV) viruses. The exogenous small interfering (si)RNA (exo-siRNA) pathway is believed to be the main antiviral defense in arthropods, including mosquitoes. During infection, double-stranded RNAs that form during viral replication and infection are cleaved by the enzyme Dicer 2 (Dcr2) into virus-specific 21 nt vsiRNAs, which are subsequently loaded into Argonaute 2 (Ago2). Ago2 then targets and subsequently cleaves complementary RNA sequences, resulting in degradation of the target viral RNA. Although various studies using silencing approaches have supported the antiviral activity of the exo-siRNA pathway in mosquitoes, and despite strong similarities between the siRNA pathway in the Drosophila melanogaster model and mosquitoes, important questions remain unanswered. The antiviral activity of Ago2 against different arboviruses has been previously demonstrated. However, silencing of Ago2 had no effect on ZIKV replication, whereas Dcr2 knockout enhanced its replication. These findings raise the question as to the role of Ago2 and Dcr2 in the control of arboviruses from different viral families in mosquitoes. Using a newly established Ago2 knockout cell line, alongside the previously reported Dcr2 knockout cell line, we investigated the impact these proteins have on the modulation of different arboviral infections. Infection of Ago2 knockout cell line with alpha- and bunyaviruses resulted in an increase of viral replication, but not in the case of ZIKV. Analysis of small RNA sequencing data in the Ago2 knockout cells revealed a lack of methylated siRNAs from different sources, such as acute and persistently infecting viruses-, TE- and transcriptome-derived RNAs. The results confirmed the importance of the exo-siRNA pathway in the defense against arboviruses, but highlights variability in its response to different viruses and the impact the siRNA pathway proteins have in controlling viral replication. Moreover, this established Ago2 knockout cell line can be used for functional Ago2 studies, as well as research on the interplay between the RNAi pathways.
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Rosendo Machado S, van der Most T, Miesen P. Genetic determinants of antiviral immunity in dipteran insects - Compiling the experimental evidence. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 119:104010. [PMID: 33476667 DOI: 10.1016/j.dci.2021.104010] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/08/2021] [Accepted: 01/09/2021] [Indexed: 06/12/2023]
Abstract
The genetic basis of antiviral immunity in dipteran insects is extensively studied in Drosophila melanogaster and advanced technologies for genetic manipulation allow a better characterization of immune responses also in non-model insect species. Especially, immunity in vector mosquitoes is recently in the spotlight, due to the medical impact that these insects have by transmitting viruses and other pathogens. Here, we review the current state of experimental evidence that supports antiviral functions for immune genes acting in different cellular pathways. We discuss the well-characterized RNA interference mechanism along with the less well-defined JAK-STAT, Toll, and IMD signaling pathways. Furthermore, we highlight the initial evidence for antiviral activity observed for the autophagy pathway, transcriptional pausing, as well as piRNA production from endogenous viral elements. We focus our review on studies from Drosophila and mosquito species from the lineages Aedes, Culex, and Anopheles, which contain major vector species responsible for virus transmission.
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Affiliation(s)
- Samara Rosendo Machado
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, the Netherlands
| | - Tom van der Most
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, the Netherlands
| | - Pascal Miesen
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, the Netherlands.
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Stokes S, Almire F, Tatham MH, McFarlane S, Mertens P, Pondeville E, Boutell C. The SUMOylation pathway suppresses arbovirus replication in Aedes aegypti cells. PLoS Pathog 2020; 16:e1009134. [PMID: 33351855 PMCID: PMC7802965 DOI: 10.1371/journal.ppat.1009134] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 01/12/2021] [Accepted: 11/09/2020] [Indexed: 11/25/2022] Open
Abstract
Mosquitoes are responsible for the transmission of many clinically important arboviruses that cause significant levels of annual mortality and socioeconomic health burden worldwide. Deciphering the mechanisms by which mosquitoes modulate arbovirus infection is crucial to understand how viral-host interactions promote vector transmission and human disease. SUMOylation is a post-translational modification that leads to the covalent attachment of the Small Ubiquitin-like MOdifier (SUMO) protein to host factors, which in turn can modulate their stability, interaction networks, sub-cellular localisation, and biochemical function. While the SUMOylation pathway is known to play a key role in the regulation of host immune defences to virus infection in humans, the importance of this pathway during arbovirus infection in mosquito vectors, such as Aedes aegypti (Ae. aegypti), remains unknown. Here we characterise the sequence, structure, biochemical properties, and tissue-specific expression profiles of component proteins of the Ae. aegypti SUMOylation pathway. We demonstrate significant biochemical differences between Ae. aegypti and Homo sapiens SUMOylation pathways and identify cell-type specific patterns of SUMO expression in Ae. aegypti tissues known to support arbovirus replication. Importantly, depletion of core SUMOylation effector proteins (SUMO, Ubc9 and PIAS) in Ae. aegypti cells led to enhanced levels of arbovirus replication from three different families; Zika (Flaviviridae), Semliki Forest (Togaviridae), and Bunyamwera (Bunyaviridae) viruses. Our findings identify an important role for mosquito SUMOylation in the cellular restriction of arboviruses that may directly influence vector competence and transmission of clinically important arboviruses. Half the world’s population is at risk of infection from arboviruses transmitted by mosquitoes. Deciphering the viral-host interactions that influence the outcome of arbovirus infection in mosquitoes is beneficial to the development of future vector control strategies to limit arbovirus transmission and viral emergence within the human population. Similar to humans, mosquitoes possess different immune pathways to limit the replication of arboviruses. While the Small Ubiquitin-like MOdifier (SUMO) pathway is known to play an important role in the regulation of immune defences to viral infection in humans, the influence of this pathway during arbovirus infection in mosquito cells is currently unknown. Here we define the conservation, biochemical activity, and tissue distribution of the core effector proteins of the Aedes aegypti SUMOylation pathway. We show that the mosquito SUMOylation pathway plays a broadly antiviral role against a wide range of clinically important arboviruses, including Zika, Semliki Forest, and Bunyamwera viruses. Our findings identify SUMOylation as an important component of the antiviral response to arbovirus infection in mosquito cells.
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Affiliation(s)
- Samuel Stokes
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
- The Pirbright Institute, Pirbright, Woking, England, United Kingdom
| | - Floriane Almire
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Michael H. Tatham
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
| | - Steven McFarlane
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Peter Mertens
- The Pirbright Institute, Pirbright, Woking, England, United Kingdom
| | - Emilie Pondeville
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
- * E-mail: (EP); (CB)
| | - Chris Boutell
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
- * E-mail: (EP); (CB)
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13
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Núñez AI, Esteve-Codina A, Gómez-Garrido J, Brustolin M, Talavera S, Berdugo M, Dabad M, Alioto T, Bensaid A, Busquets N. Alteration in the Culex pipiens transcriptome reveals diverse mechanisms of the mosquito immune system implicated upon Rift Valley fever phlebovirus exposure. PLoS Negl Trop Dis 2020; 14:e0008870. [PMID: 33301456 PMCID: PMC7755283 DOI: 10.1371/journal.pntd.0008870] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 12/22/2020] [Accepted: 10/10/2020] [Indexed: 01/02/2023] Open
Abstract
Rift Valley fever phlebovirus (RVFV) causes an emerging zoonotic disease and is mainly transmitted by Culex and Aedes mosquitoes. While Aedes aegypti-dengue virus (DENV) is the most studied model, less is known about the genes involved in infection-responses in other mosquito-arboviruses pairing. The main objective was to investigate the molecular responses of Cx. pipiens to RVFV exposure focusing mainly on genes implicated in innate immune responses. Mosquitoes were fed with blood spiked with RVFV. The fully-engorged females were pooled at 3 different time points: 2 hours post-exposure (hpe), 3- and 14-days post-exposure (dpe). Pools of mosquitoes fed with non-infected blood were also collected for comparisons. Total RNA from each mosquito pool was subjected to RNA-seq analysis and a de novo transcriptome was constructed. A total of 451 differentially expressed genes (DEG) were identified. Most of the transcriptomic alterations were found at an early infection stage after RVFV exposure. Forty-eight DEG related to immune infection-response were characterized. Most of them were related with the RNAi system, Toll and IMD pathways, ubiquitination pathway and apoptosis. Our findings provide for the first time a comprehensive view on Cx. pipiens-RVFV interactions at the molecular level. The early depletion of RNAi pathway genes at the onset of the RVFV infection would allow viral replication in mosquitoes. While genes from the Toll and IMD immune pathways were altered in response to RVFV none of the DEG were related to the JAK/STAT pathway. The fact that most of the DEG involved in the Ubiquitin-proteasome pathway (UPP) or apoptosis were found at an early stage of infection would suggest that apoptosis plays a regulatory role in infected Cx. pipiens midguts. This study provides a number of target genes that could be used to identify new molecular targets for vector control. Rift valley fever (RVF) is an emerging zoonotic disease and it is caused by RVFV. This virus is commonly transmitted in endemic areas between wild ruminants and mosquitoes, mainly by mosquitoes of Culex and Aedes genus. Starting from the year 2000, several outbreaks have been reported outside Sub Saharan Africa, in countries facing the Mediterranean Sea (Egypt), or Yemen and Saudi Arabia. Available vaccines for ruminants present limited efficacy or residual pathogenic effects. Consequently, new strategies are urgently required to limit the expansion of this zoonotic virus. The main objective of this work is to investigate transcriptional alterations of Cx. pipiens to RVFV focusing mainly on genes implicated in conventional innate immunity pathways, RNAi mechanisms and the apoptotic process in order to evaluate the involvement of these genes in viral infection. The immune altered genes here described could be potential targets to control RVFV infection in mosquitoes. Some of the genes related to the immune defense response were previously described in others mosquito-arbovirus models, as well as in Drosophila and human. To our knowledge, this study highlights for the first time the Cx. pipiens-RVFV interactions in terms of defense infection-response and provides information for developing in the future new approaches to prevent and control the expansion of the virus.
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Affiliation(s)
- Ana I. Núñez
- IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Anna Esteve-Codina
- CNAG-CRG, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
| | - Jèssica Gómez-Garrido
- CNAG-CRG, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
| | - Marco Brustolin
- IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, Bellaterra, Spain
- Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Sandra Talavera
- IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Miguel Berdugo
- Instituto de Biología Evolutiva, Universitat Pompeu i Fabra-CSIC, Dr. Aigüader 88, Barcelona, Spain
| | - Marc Dabad
- CNAG-CRG, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
| | - Tyler Alioto
- CNAG-CRG, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
- Universitat Pompeu i Fabra (UPF), Barcelona, Catalonia, Spain
| | - Albert Bensaid
- IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Núria Busquets
- IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, Bellaterra, Spain
- * E-mail:
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14
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Forth JH, Forth LF, Lycett S, Bell-Sakyi L, Keil GM, Blome S, Calvignac-Spencer S, Wissgott A, Krause J, Höper D, Kampen H, Beer M. Identification of African swine fever virus-like elements in the soft tick genome provides insights into the virus' evolution. BMC Biol 2020; 18:136. [PMID: 33032594 PMCID: PMC7542975 DOI: 10.1186/s12915-020-00865-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 09/04/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND African swine fever virus (ASFV) is a most devastating pathogen affecting swine. In 2007, ASFV was introduced into Eastern Europe where it continuously circulates and recently reached Western Europe and Asia, leading to a socio-economic crisis of global proportion. In Africa, where ASFV was first described in 1921, it is transmitted between warthogs and soft ticks of the genus Ornithodoros in a so-called sylvatic cycle. However, analyses into this virus' evolution are aggravated by the absence of any closely related viruses. Even ancient endogenous viral elements, viral sequences integrated into a host's genome many thousand years ago that have proven extremely valuable to analyse virus evolution, remain to be identified. Therefore, the evolution of ASFV, the only known DNA virus transmitted by arthropods, remains a mystery. RESULTS For the identification of ASFV-like sequences, we sequenced DNA from different recent Ornithodoros tick species, e.g. O. moubata and O. porcinus, O. moubata tick cells and also 100-year-old O. moubata and O. porcinus ticks using high-throughput sequencing. We used BLAST analyses for the identification of ASFV-like sequences and further analysed the data through phylogenetic reconstruction and molecular clock analyses. In addition, we performed tick infection experiments as well as additional small RNA sequencing of O. moubata and O. porcinus soft ticks. CONCLUSION Here, we show that soft ticks of the Ornithodoros moubata group, the natural arthropod vector of ASFV, harbour African swine fever virus-like integrated (ASFLI) elements corresponding to up to 10% (over 20 kb) of the ASFV genome. Through orthologous dating and molecular clock analyses, we provide data suggesting that integration could have occurred over 1.47 million years ago. Furthermore, we provide data showing ASFLI-element specific siRNA and piRNA in ticks and tick cells allowing for speculations on a possible role of ASFLI-elements in RNA interference-based protection against ASFV in ticks. We suggest that these elements, shaped through many years of co-evolution, could be part of an evolutionary virus-vector 'arms race', a finding that has not only high impact on our understanding of the co-evolution of viruses with their hosts but also provides a glimpse into the evolution of ASFV.
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Affiliation(s)
- Jan H Forth
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald-Insel Riems, Germany
| | - Leonie F Forth
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald-Insel Riems, Germany
| | - Samantha Lycett
- The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, Scotland, UK
| | - Lesley Bell-Sakyi
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, 146 Brownlow Hill, Liverpool, L3 5RF, UK
| | - Günther M Keil
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald-Insel Riems, Germany
| | - Sandra Blome
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald-Insel Riems, Germany
| | | | - Antje Wissgott
- Max Planck Institute for the Science of Human History, Kahlaische Str. 10, 07745, Jena, Germany
| | - Johannes Krause
- Max Planck Institute for the Science of Human History, Kahlaische Str. 10, 07745, Jena, Germany
| | - Dirk Höper
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald-Insel Riems, Germany
| | - Helge Kampen
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald-Insel Riems, Germany
| | - Martin Beer
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald-Insel Riems, Germany.
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15
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Endogenous Viral Element-Derived Piwi-Interacting RNAs (piRNAs) Are Not Required for Production of Ping-Pong-Dependent piRNAs from Diaphorina citri Densovirus. mBio 2020; 11:mBio.02209-20. [PMID: 32994324 PMCID: PMC7527727 DOI: 10.1128/mbio.02209-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Piwi-interacting RNAs (piRNAs) are a class of small RNAs primarily responsible for silencing transposons in the animal germ line. The ping-pong cycle, the posttranscriptional silencing branch of the piRNA pathway, relies on piRNAs produced from endogenous transposon remnants to direct cleavage of transposon RNA via association with Piwi-family Argonaute proteins. In some mosquito species and mosquito-derived cell lines expressing a functionally expanded group of Piwi-family Argonaute proteins, both RNA and DNA viruses are targeted by piRNAs in a manner thought to involve direct processing of exogenous viral RNA into piRNAs. Whether viruses are targeted by piRNAs in nonmosquito species is unknown. Partial integrations of DNA and nonretroviral RNA virus genomes, termed endogenous viral elements (EVEs), are abundant in arthropod genomes and often produce piRNAs that are speculated to target cognate viruses through the ping-pong cycle. Here, we describe a Diaphorina citri densovirus (DcDV)-derived EVE in the genome of Diaphorina citri We found that this EVE gives rise to DcDV-specific primary piRNAs and is unevenly distributed among D. citri populations. Unexpectedly, we found that DcDV is targeted by ping-pong-dependent virus-derived piRNAs (vpiRNAs) in D. citri lacking the DcDV-derived EVE, while four naturally infecting RNA viruses of D. citri are not targeted by vpiRNAs. Furthermore, a recombinant Cricket paralysis virus containing a portion of the DcDV genome corresponding to the DcDV-derived EVE was not targeted by vpiRNAs during infection in D. citri harboring the EVE. These results demonstrate that viruses can be targeted by piRNAs in a nonmosquito species independently of endogenous piRNAs.IMPORTANCE Small RNAs serve as specificity determinants of antiviral responses in insects. Piwi-interacting RNAs (piRNAs) are a class of small RNAs found in animals, and their primary role is to direct antitransposon responses. These responses require endogenous piRNAs complementary to transposon RNA. Additionally, piRNAs have been shown to target RNA and DNA viruses in some mosquito species. In contrast to transposons, targeting of viruses by the piRNA pathway in these mosquito species does not require endogenous piRNAs. Here, we show that piRNAs target a DNA virus, but not RNA viruses, in an agricultural insect pest. We found that targeting of this DNA virus did not require endogenous piRNAs and that endogenous piRNAs did not mediate targeting of an RNA virus with which they shared complementary sequence. Our results highlight differences between mosquitoes and our experimental system and raise the possibility that DNA viruses may be targeted by piRNAs in other species.
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16
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Deng Y, Zhao H, Yang S, Zhang L, Zhang L, Hou C. Screening and Validation of Reference Genes for RT-qPCR Under Different Honey Bee Viral Infections and dsRNA Treatment. Front Microbiol 2020; 11:1715. [PMID: 32849362 PMCID: PMC7406718 DOI: 10.3389/fmicb.2020.01715] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 06/30/2020] [Indexed: 01/22/2023] Open
Abstract
Honey bee viruses are one of the most important pathogens that have contributed to the decrease in honey bee colony health. To analyze the infection dynamics of honey bee viruses, quantification of viral gene expression by RT-qPCR is necessary. However, suitable reference genes have not been reported from viral and RNAi studies of honey bee. Here, we evaluated the expression of 11 common reference genes (ache2, rps18, β-actin, tbp, tif, rpl32, gadph, ubc, α-tubulin, rpl14, and rpsa) from Apis mellifera (Am) and Apis cerana (Ac) under Israeli acute paralysis virus (IAPV), chronic bee paralysis virus (CBPV), and Chinese sacbrood virus (CSBV) infection as well as dsRNA-PGRP-SA treatment, and we confirmed their validation by evaluating the levels of the defensin 1 and prophenoloxidase (ppo) genes during viral infection. Our results showed that the expression of selected genes varied under different viral infections. ache2, rps18, β-actin, tbp, and tif can be used to normalize expression levels in Apis mellifera under IAPV infection, while the combination of actin and tif is suitable for CBPV-infected experiments. The combination of rpl14, tif, rpsa, ubc, and ache2 as well as more reference genes is suitable for CSBV treatment in Apis cerana. Rpl14, tif, rps18, ubc, and α-tubulin were the most stable reference genes under dsRNA treatment in Apis mellifera. Furthermore, the geNorm and NormFinder algorithms showed that tif was the best suitable reference gene for these four treatments. This study screened and validated suitable reference genes for the quantification of viral levels in honey bee, as well as for RNAi experiments.
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Affiliation(s)
- Yanchun Deng
- Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, China.,Key laboratory of Pollinating Insect Biology, Ministry of Agriculture and Rural Affairs, Beijing, China.,Graduate School of Chinese Academy of Agricultural Sciences, Beijing, China
| | - Hongxia Zhao
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Institute of Applied Biological Resources, Guangdong Academy of Science, Guangzhou, China
| | - Sa Yang
- Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, China.,Key laboratory of Pollinating Insect Biology, Ministry of Agriculture and Rural Affairs, Beijing, China
| | - Li Zhang
- Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, China.,Key laboratory of Pollinating Insect Biology, Ministry of Agriculture and Rural Affairs, Beijing, China
| | - Lina Zhang
- Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, China.,Key laboratory of Pollinating Insect Biology, Ministry of Agriculture and Rural Affairs, Beijing, China
| | - Chunsheng Hou
- Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, China.,Key laboratory of Pollinating Insect Biology, Ministry of Agriculture and Rural Affairs, Beijing, China
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17
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aBravo Is a Novel Aedes aegypti Antiviral Protein that Interacts with, but Acts Independently of, the Exogenous siRNA Pathway Effector Dicer 2. Viruses 2020; 12:v12070748. [PMID: 32664591 PMCID: PMC7411624 DOI: 10.3390/v12070748] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/03/2020] [Accepted: 07/08/2020] [Indexed: 12/12/2022] Open
Abstract
Mosquitoes, such as Aedes aegypti, 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 Ae. aegypti 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 (aedine broadly active antiviral protein), 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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18
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Parry R, Naccache F, Ndiaye EH, Fall G, Castelli I, Lühken R, Medlock J, Cull B, Hesson JC, Montarsi F, Failloux AB, Kohl A, Schnettler E, Diallo M, Asgari S, Dietrich I, Becker SC. Identification and RNAi Profile of a Novel Iflavirus Infecting Senegalese Aedes vexans arabiensis Mosquitoes. Viruses 2020; 12:E440. [PMID: 32295109 PMCID: PMC7232509 DOI: 10.3390/v12040440] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 04/10/2020] [Accepted: 04/11/2020] [Indexed: 01/16/2023] Open
Abstract
The inland floodwater mosquito Aedes vexans (Meigen, 1830) is a competent vector of numerous arthropod-borne viruses such as Rift Valley fever virus (Phenuiviridae) and Zika virus (Flaviviridae). Aedes vexans spp. have widespread Afrotropical distribution and are common European cosmopolitan mosquitoes. We examined the virome of Ae. vexans arabiensis samples from Barkédji village, Senegal, with small RNA sequencing, bioinformatic analysis, and RT-PCR screening. We identified a novel 9494 nt iflavirus (Picornaviridae) 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 Venturia canescens (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) Ae. vexans arabiensis laboratory samples and wild-caught mosquitoes from Barkédji suggest that AvIFV is ubiquitous in these mosquitoes. Further, we screened wild-caught European Ae. vexans 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 Aedes viruses and the host RNAi response towards iflaviruses.
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Affiliation(s)
- Rhys Parry
- Australian Infectious Diseases Research Centre, School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia; (R.P.); (S.A.)
| | - Fanny Naccache
- Institute for Parasitology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany;
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - El Hadji Ndiaye
- Pole de Zoologie Médicale, Institut Pasteur de Dakar, Dakar BP 220, Senegal; (E.H.N.); (M.D.)
| | - Gamou Fall
- Pole de Virologie, Unité des Arbovirus et Virus de Fièvres Hémorragiques, Institut Pasteur de Dakar, Dakar BP 220, Senegal;
| | - Ilaria Castelli
- Arboviruses and Insect Vectors, Department of Virology, Institut Pasteur, 75724 Paris, France; (I.C.); (A.-B.F.)
| | - Renke Lühken
- Faculty of Mathematics, Informatics and Natural Sciences, Universiät Hamburg, 20148 Hamburg, Germany; (R.L.); (E.S.)
- Bernhard-Nocht-Institute for Tropical Medicine, 20359 Hamburg, Germany
| | - Jolyon Medlock
- Health Protection Research Unit in Emerging and Zoonotic Infection, Public Health England, Porton Down, Salisbury SP4 0JG, UK;
- Medical Entomology & Zoonoses Ecology, Emergency Response Department Science & Technology, Public Health England, Porton Down, Salisbury SP4 0JG, UK; or
| | - Benjamin Cull
- Medical Entomology & Zoonoses Ecology, Emergency Response Department Science & Technology, Public Health England, Porton Down, Salisbury SP4 0JG, UK; or
| | - Jenny C. Hesson
- Department of Medical Biochemistry and Microbiology/Zoonosis Science Center, Uppsala University, 75237 Uppsala, Sweden;
| | - Fabrizio Montarsi
- Laboratory of Parasitology, Istituto Zooprofilattico Sperimentale delle Venezie, 35020 Legnaro (Padua), Italy;
| | - Anna-Bella Failloux
- Arboviruses and Insect Vectors, Department of Virology, Institut Pasteur, 75724 Paris, France; (I.C.); (A.-B.F.)
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK;
| | - Esther Schnettler
- Faculty of Mathematics, Informatics and Natural Sciences, Universiät Hamburg, 20148 Hamburg, Germany; (R.L.); (E.S.)
- Bernhard-Nocht-Institute for Tropical Medicine, 20359 Hamburg, Germany
- German Centre for Infection Research, partner site Hamburg-Lübeck-Borstel-Riems, 20359 Hamburg, Germany
| | - Mawlouth Diallo
- Pole de Zoologie Médicale, Institut Pasteur de Dakar, Dakar BP 220, Senegal; (E.H.N.); (M.D.)
| | - Sassan Asgari
- Australian Infectious Diseases Research Centre, School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia; (R.P.); (S.A.)
| | | | - Stefanie C. Becker
- Institute for Parasitology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany;
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
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19
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McFarlane M, Almire F, Kean J, Donald CL, McDonald A, Wee B, Lauréti M, Varjak M, Terry S, Vazeille M, Gestuveo RJ, Dietrich I, Loney C, Failloux AB, Schnettler E, Pondeville E, Kohl A. The Aedes aegypti Domino Ortholog p400 Regulates Antiviral Exogenous Small Interfering RNA Pathway Activity and ago-2 Expression. mSphere 2020; 5:e00081-20. [PMID: 32269152 PMCID: PMC7142294 DOI: 10.1128/msphere.00081-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 03/13/2020] [Indexed: 02/03/2023] Open
Abstract
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 (Togaviridae) both in Aedes aegypti-derived cells and in vivo Antiviral activity of p400 was also demonstrated against chikungunya virus (Togaviridae) and Bunyamwera virus (Peribunyaviridae) but not Zika virus (Flaviviridae). p400 was found to be expressed across mosquito tissues and regulated ago-2 but not dcr-2 transcript levels in A. aegypti 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 Drosophila melanogasterIMPORTANCE Female Aedes aegypti 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 A. aegypti p400, whose ortholog Domino in Drosophila melanogaster is a chromatin-remodeling ATPase member of the Tip60 complex, regulates siRNA pathway activity and controls ago-2 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 A. aegypti mosquitoes.
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Affiliation(s)
- Melanie McFarlane
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Floriane Almire
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Joy Kean
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Claire L Donald
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Alma McDonald
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Bryan Wee
- Usher Institute for Population Health Sciences & Informatics, University of Edinburgh, Edinburgh, United Kingdom
| | - Mathilde Lauréti
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Margus Varjak
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Sandra Terry
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Marie Vazeille
- Arboviruses and Insect Vectors Unit, Department of Virology, Institut Pasteur, Paris, France
| | - Rommel J Gestuveo
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
- Division of Biological Sciences, University of the Philippines Visayas, Miagao, Philippines
| | - Isabelle Dietrich
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Colin Loney
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Anna-Bella Failloux
- Arboviruses and Insect Vectors Unit, Department of Virology, Institut Pasteur, Paris, France
| | - Esther Schnettler
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Emilie Pondeville
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
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20
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Liu J, Swevers L, Kolliopoulou A, Smagghe G. Arboviruses and the Challenge to Establish Systemic and Persistent Infections in Competent Mosquito Vectors: The Interaction With the RNAi Mechanism. Front Physiol 2019; 10:890. [PMID: 31354527 PMCID: PMC6638189 DOI: 10.3389/fphys.2019.00890] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 06/27/2019] [Indexed: 12/15/2022] Open
Abstract
Arboviruses are capable to establish long-term persistent infections in mosquitoes that do not affect significantly the physiology of the insect vectors. Arbovirus infections are controlled by the RNAi machinery via the production of viral siRNAs and the formation of RISC complexes targeting viral genomes and mRNAs. Engineered arboviruses that contain cellular gene sequences can therefore be transformed to "viral silencing vectors" for studies of gene function in reverse genetics approaches. More specifically, "ideal" viral silencing vectors must be competent to induce robust RNAi effects while other interactions with the host immune system should be kept at a minimum to reduce non-specific effects. Because of their inconspicuous nature, arboviruses may approach the "ideal" viral silencing vectors in insects and it is therefore worthwhile to study the mechanisms by which the interactions with the RNAi machinery occur. In this review, an analysis is presented of the antiviral RNAi response in mosquito vectors with respect to the major types of arboviruses (alphaviruses, flaviviruses, bunyaviruses, and others). With respect to antiviral defense, the exo-RNAi pathway constitutes the major mechanism while the contribution of both miRNAs and viral piRNAs remains a contentious issue. However, additional mechanisms exist in mosquitoes that are capable to enhance or restrict the efficiency of viral silencing vectors such as the amplification of RNAi effects by DNA forms, the existence of incorporated viral elements in the genome and the induction of a non-specific systemic response by Dicer-2. Of significance is the observation that no major "viral suppressors of RNAi" (VSRs) seem to be encoded by arboviral genomes, indicating that relatively tight control of the activity of the RNA-dependent RNA polymerase (RdRp) may be sufficient to maintain the persistent character of arbovirus infections. Major strategies for improvement of viral silencing vectors therefore are proposed to involve engineering of VSRs and modifying of the properties of the RdRp. Because of safety issues (pathogen status), however, arbovirus-based silencing vectors are not well suited for practical applications, such as RNAi-based mosquito control. In that case, related mosquito-specific viruses that also establish persistent infections and may cause similar RNAi responses may represent a valuable alternative solution.
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Affiliation(s)
- Jisheng Liu
- School of Life Sciences, Guangzhou University, Guangzhou, China
| | - Luc Swevers
- Institute of Biosciences and Applications, National Centre of Scientific Research “Demokritos”, Athens, Greece
| | - Anna Kolliopoulou
- Institute of Biosciences and Applications, National Centre of Scientific Research “Demokritos”, Athens, Greece
| | - Guy Smagghe
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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21
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Artigas-Jerónimo S, Alberdi P, Villar Rayo M, Cabezas-Cruz A, Prados PJE, Mateos-Hernández L, de la Fuente J. Anaplasma phagocytophilum modifies tick cell microRNA expression and upregulates isc-mir-79 to facilitate infection by targeting the Roundabout protein 2 pathway. Sci Rep 2019; 9:9073. [PMID: 31235752 PMCID: PMC6591238 DOI: 10.1038/s41598-019-45658-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 06/12/2019] [Indexed: 12/13/2022] Open
Abstract
The microRNAs (miRNAs) are a class of small noncoding RNAs that have important regulatory roles in multicellular organisms including innate and adaptive immune pathways to control bacterial, parasite and viral infections, and pathogens could modify host miRNA profile to facilitate infection and multiplication. Therefore, understanding the function of host miRNAs in response to pathogen infection is relevant to characterize host-pathogen molecular interactions and to provide new targets for effective new interventions for the control infectious diseases. The objective of this study was to characterize the dynamics and functional significance of the miRNA response of the tick vector Ixodes scapularis in response to Anaplasma phagocytophilum infection, the causative agent of human and animal granulocytic anaplasmosis. To address this objective, the composition of tick miRNAs, functional annotation, and expression profiling was characterized using high throughout RNA sequencing in uninfected and A. phagocytophilum-infected I. scapularis ISE6 tick cells, a model for tick hemocytes involved in pathogen infection. The results provided new evidences on the role of tick miRNA during pathogen infection, and showed that A. phagocytophilum modifies I. scapularis tick cell miRNA profile and upregulates isc-mir-79 to facilitate infection by targeting the Roundabout protein 2 (Robo2) pathway. Furthermore, these results suggested new targets for interventions to control pathogen infection in ticks.
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Affiliation(s)
- Sara Artigas-Jerónimo
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005, Ciudad, Real, Spain
| | - Pilar Alberdi
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005, Ciudad, Real, Spain
| | - Margarita Villar Rayo
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005, Ciudad, Real, Spain
| | - Alejandro Cabezas-Cruz
- UMR BIPAR, INRA, Ecole Nationale Vétérinaire d'Alfort, ANSES, Université Paris-Est, 94700, Maisons-Alfort, France
| | - Pedro J Espinosa Prados
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005, Ciudad, Real, Spain
| | - Lourdes Mateos-Hernández
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005, Ciudad, Real, Spain
- UMR BIPAR, INRA, Ecole Nationale Vétérinaire d'Alfort, ANSES, Université Paris-Est, 94700, Maisons-Alfort, France
| | - José de la Fuente
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005, Ciudad, Real, Spain.
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, 74078, USA.
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Assessing the Potential Interactions between Cellular miRNA and Arboviral Genomic RNA in the Yellow Fever Mosquito, Aedes aegypti. Viruses 2019; 11:v11060540. [PMID: 31185697 PMCID: PMC6631873 DOI: 10.3390/v11060540] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 06/04/2019] [Accepted: 06/05/2019] [Indexed: 01/10/2023] Open
Abstract
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 Aedes aegypti 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 Ae. aegypti. 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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23
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Kolliopoulou A, Santos D, Taning CNT, Wynant N, Vanden Broeck J, Smagghe G, Swevers L. PIWI pathway against viruses in insects. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1555. [PMID: 31183996 DOI: 10.1002/wrna.1555] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/06/2019] [Accepted: 05/07/2019] [Indexed: 12/26/2022]
Abstract
Piwi-interacting RNAs (piRNAs) are an animal-specific class of small non-coding RNAs that are generated via a biogenesis pathway distinct from small interfering RNAs (siRNAs) and microRNAs (miRNAs). There are variations in piRNA biogenesis that depend on several factors, such as the cell type (germline or soma), the organism, and the purpose for which they are being produced, such as transposon-targeting, viral-targeting, or gene-derived piRNAs. Interestingly, the genes involved in the PIWI/piRNA pathway are more rapidly evolving compared with other RNA interference (RNAi) genes. In this review, the role of the piRNA pathway in the antiviral response is reviewed based on recent findings in insect models such as Drosophila, mosquitoes, midges and the silkworm, Bombyx mori. We extensively discuss the special features that characterize host-virus piRNA responses with respect to the proteins and the genes involved, the viral piRNAs' sequence characteristics, the target strand orientation biases as well as the viral piRNA target hotspots across the viral genomes. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > RNAi: Mechanisms of Action Regulatory RNAs/RNAi/Riboswitches > Biogenesis of Effector Small RNAs.
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Affiliation(s)
- Anna Kolliopoulou
- Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Dulce Santos
- Molecular Developmental Physiology and Signal Transduction Research Group, Animal Physiology and Neurobiology Division, Department of Biology, KU Leuven, Leuven, Belgium
| | - Clauvis Nji Tizi Taning
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Niels Wynant
- Molecular Developmental Physiology and Signal Transduction Research Group, Animal Physiology and Neurobiology Division, Department of Biology, KU Leuven, Leuven, Belgium
| | - Jozef Vanden Broeck
- Molecular Developmental Physiology and Signal Transduction Research Group, Animal Physiology and Neurobiology Division, Department of Biology, KU Leuven, Leuven, Belgium
| | - Guy Smagghe
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Luc Swevers
- Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", Athens, Greece
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24
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Kyre BR, Rodrigues TB, Rieske LK. RNA interference and validation of reference genes for gene expression analyses using qPCR in southern pine beetle, Dendroctonus frontalis. Sci Rep 2019; 9:5640. [PMID: 30948805 PMCID: PMC6449504 DOI: 10.1038/s41598-019-42072-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 03/19/2019] [Indexed: 01/24/2023] Open
Abstract
RNA interference (RNAi) is a highly specific gene-silencing mechanism that can cause rapid insect mortality when essential genes are targeted. RNAi is being developed as a tool for integrated pest management of some crop pests. Here we focus on an aggressive forest pest that kills extensive tracts of pine forests, the southern pine beetle (SPB), Dendroctonus frontalis. We sought to identify reference genes for quantitative real-time PCR (qPCR) and validate RNAi responses in SPB by mortality and gene silencing analysis. Using an adult beetle feeding bioassay for oral ingestion of dsRNA, we measured the expression and demonstrated knockdown of target genes as well as insect mortality after ingestion of target genes. Our study validates reference genes for expression analyses and demonstrates highly effective RNAi responses in SPB, with RNAi response to some target dsRNAs causing 100% beetle mortality after ingestion.
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Affiliation(s)
- Bethany R Kyre
- Department of Entomology, University of Kentucky, Lexington, KY, 40546-0091, USA
| | - Thais B Rodrigues
- Department of Entomology, University of Kentucky, Lexington, KY, 40546-0091, USA
- Greenlight BioSciences, Medford, MA, 02155, USA
| | - Lynne K Rieske
- Department of Entomology, University of Kentucky, Lexington, KY, 40546-0091, USA.
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25
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Göertz GP, Miesen P, Overheul GJ, van Rij RP, van Oers MM, Pijlman GP. Mosquito Small RNA Responses to West Nile and Insect-Specific Virus Infections in Aedes and Culex Mosquito Cells. Viruses 2019; 11:v11030271. [PMID: 30889941 PMCID: PMC6466260 DOI: 10.3390/v11030271] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/12/2019] [Accepted: 03/14/2019] [Indexed: 12/15/2022] Open
Abstract
Small RNA mediated responses are essential for antiviral defence in mosquitoes, however, they appear to differ per virus-vector combination. To further investigate the diversity of small RNA responses against viruses in mosquitoes, we applied a small RNA deep sequencing approach on five mosquito cell lines: Culex tarsalis CT cells, Aedes albopictus U4.4 and C6/36 cells, Ae. aegypti Aag2 cells (cleared from cell fusing agent virus and Culex Y virus (CYV) by repetitive dsRNA transfections) and Ae. pseudoscutellaris AP-61 cells. De novo assembly of small RNAs revealed the presence of Phasi Charoen-like virus (PCLV), Calbertado virus, Flock House virus and a novel narnavirus in CT cells, CYV in U4.4 cells, and PCLV in Aag2 cells, whereas no insect-specific viruses (ISVs) were detected in C6/36 and AP-61 cells. Next, we investigated the small RNA responses to the identified ISVs and to acute infection with the arthropod-borne West Nile virus (WNV). We demonstrate that AP-61 and C6/36 cells do not produce siRNAs to WNV infection, suggesting that AP-61, like C6/36, are Dicer-2 deficient. CT cells produced a strong siRNA response to the persistent ISVs and acute WNV infection. Interestingly, CT cells also produced viral PIWI-interacting (pi)RNAs to PCLV, but not to WNV or any of the other ISVs. In contrast, in U4.4 and Aag2 cells, WNV siRNAs, and pi-like RNAs without typical ping-pong piRNA signature were observed, while this signature was present in PCLV piRNAs in Aag2 cells. Together, our results demonstrate that mosquito small RNA responses are strongly dependent on both the mosquito cell type and/or the mosquito species and family of the infecting virus.
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Affiliation(s)
- Giel P Göertz
- Laboratory of Virology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
| | - Pascal Miesen
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands.
| | - Gijs J Overheul
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands.
| | - Ronald P van Rij
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands.
| | - Monique M van Oers
- Laboratory of Virology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
| | - Gorben P Pijlman
- Laboratory of Virology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
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26
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Carissimo G, Ng LFP. Understanding Molecular Pathogenesis with Chikungunya Virus Research Tools. Curr Top Microbiol Immunol 2019; 435:33-53. [PMID: 30888547 DOI: 10.1007/82_2019_158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Since its re-emergence in 2006, Chikungunya has been a major health concern in endemic areas. Transmitted by Aedes mosquitoes to mammalian hosts, Chikungunya leads to persistent debilitating symptoms in a high proportion of symptomatic human cases. In this review, we present several tools on the mosquito vector side as well as on the mammalian side that have been used to advance research on Chikungunya transmission and immunopathogenesis. These tools lead to key understandings of viral replication in both hosts, and innate and adaptive responses mediating virus clearance and pathology in mammals. This comprehension of viral mechanisms has allowed the development of promising treatment avenues in animal models that will need to be further explored. However, research efforts need to continue in order to develop better and unbiased tools to assess antiviral and treatment strategies as well as further understand immune mechanisms at play in human pathologies.
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Affiliation(s)
- Guillaume Carissimo
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore, Singapore
| | - Lisa F P Ng
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore, Singapore. .,Institute of Infection and Global Health, University of Liverpool, Liverpool, UK. .,Laboratory of Microbial Immunity, Singapore Immunology Network, 8A Biomedical Grove, #04-06, Immunos, Biopolis, 138648, Singapore.
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27
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Donald CL, Varjak M, Aguiar ERGR, Marques JT, Sreenu VB, Schnettler E, Kohl A. Antiviral RNA Interference Activity in Cells of the Predatory Mosquito, Toxorhynchites amboinensis. Viruses 2018; 10:v10120694. [PMID: 30563205 PMCID: PMC6316411 DOI: 10.3390/v10120694] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 11/19/2018] [Accepted: 12/04/2018] [Indexed: 12/13/2022] Open
Abstract
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 Toxorhynchites amboinensis, 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 Tx. amboinensis 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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Affiliation(s)
- Claire L Donald
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland G61 1QH, UK.
| | - Margus Varjak
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland G61 1QH, UK.
| | - Eric Roberto Guimarães Rocha Aguiar
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 6627-Pampulha-Belo Horizonte-MG, CEP 31270-901, Brazil.
| | - João T Marques
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 6627-Pampulha-Belo Horizonte-MG, CEP 31270-901, Brazil.
| | - Vattipally B Sreenu
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland G61 1QH, UK.
| | - Esther Schnettler
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland G61 1QH, UK.
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland G61 1QH, UK.
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28
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Franzke K, Leggewie M, Sreenu VB, Jansen S, Heitmann A, Welch SR, Brennan B, Elliott RM, Tannich E, Becker SC, Schnettler E. Detection, infection dynamics and small RNA response against Culex Y virus in mosquito-derived cells. J Gen Virol 2018; 99:1739-1745. [PMID: 30394867 DOI: 10.1099/jgv.0.001173] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many insect cell lines are persistently infected with insect-specific viruses (ISV) often unrecognized by the scientific community. Considering recent findings showing the possibility of interference between arbovirus and ISV infections, it is important to pay attention to ISV-infected cell lines. One example is the Entomobirnavirus, Culex Y virus (CYV). Here we describe the detection of CYV using a combination of small RNA sequencing, electron microscopy and PCR in mosquito cell lines Aag2, U4.4 and C7-10. We found CYV-specific small RNAs in all three cell lines. Interestingly, the magnitude of the detected viral RNA genome is variable among cell passages and leads to irregular detection via electron microscopy. Gaining insights into the presence of persistent ISV infection in commonly used mosquito cells and their interactions with the host immune system is beneficial for evaluating the outcome of co-infections with arboviruses of public health concern.
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Affiliation(s)
- Kati Franzke
- 1Institute of Infectology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Mayke Leggewie
- 2Bernhard Nocht Institute for Tropical Medicine, WHO Collaborating Centre for Arbovirus and Hemorrhagic Fever Reference and Research, Hamburg, Germany.,3German Centre for Infection research, partner side Hamburg-Lübeck-Borstel-Riems, Hamburg, Germany
| | | | - Stephanie Jansen
- 2Bernhard Nocht Institute for Tropical Medicine, WHO Collaborating Centre for Arbovirus and Hemorrhagic Fever Reference and Research, Hamburg, Germany
| | - Anna Heitmann
- 2Bernhard Nocht Institute for Tropical Medicine, WHO Collaborating Centre for Arbovirus and Hemorrhagic Fever Reference and Research, Hamburg, Germany
| | - Stephen R Welch
- 4MRC - University of Glasgow Centre of Virus Research, Glasgow, UK
| | - Benjamin Brennan
- 4MRC - University of Glasgow Centre of Virus Research, Glasgow, UK
| | | | - Egbert Tannich
- 2Bernhard Nocht Institute for Tropical Medicine, WHO Collaborating Centre for Arbovirus and Hemorrhagic Fever Reference and Research, Hamburg, Germany.,3German Centre for Infection research, partner side Hamburg-Lübeck-Borstel-Riems, Hamburg, Germany
| | - Stefanie C Becker
- 5Institute for Parasitology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Esther Schnettler
- 4MRC - University of Glasgow Centre of Virus Research, Glasgow, UK.,2Bernhard Nocht Institute for Tropical Medicine, WHO Collaborating Centre for Arbovirus and Hemorrhagic Fever Reference and Research, Hamburg, Germany.,3German Centre for Infection research, partner side Hamburg-Lübeck-Borstel-Riems, Hamburg, Germany
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29
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Abstract
There are several RNA interference (RNAi) pathways in insects. The small interfering RNA pathway is considered to be the main antiviral mechanism of the innate immune system; however, virus-specific P-element-induced Wimpy testis gene (PIWI)-interacting RNAs (vpiRNAs) have also been described, especially in mosquitoes. Understanding the antiviral potential of the RNAi pathways is important, given that many human and animal pathogens are transmitted by mosquitoes, such as Zika virus, dengue virus and chikungunya virus. In recent years, significant progress has been made to characterize the piRNA pathway in mosquitoes (including the possible antiviral activity) and to determine the differences between mosquitoes and the model organism Drosophila melanogaster. The new findings, especially regarding vpiRNA in mosquitoes, as well as important questions that need to be tackled in the future, are discussed in this review.
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Affiliation(s)
- Margus Varjak
- 1MRC - University of Glasgow Centre for Virus Research, Glasgow, G61 1QH, UK
| | - Mayke Leggewie
- 2Bernhard-Nocht-Institute for Tropical Medicine, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany.,3German Centre for Infection Research (DZIF), partner site Hamburg-Luebeck-Borstel-Riems, Hamburg 20359, Germany
| | - Esther Schnettler
- 2Bernhard-Nocht-Institute for Tropical Medicine, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany.,3German Centre for Infection Research (DZIF), partner site Hamburg-Luebeck-Borstel-Riems, Hamburg 20359, Germany
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Harsh S, Ozakman Y, Kitchen SM, Paquin-Proulx D, Nixon DF, Eleftherianos I. Dicer-2 Regulates Resistance and Maintains Homeostasis against Zika Virus Infection in Drosophila. THE JOURNAL OF IMMUNOLOGY 2018; 201:3058-3072. [PMID: 30305326 DOI: 10.4049/jimmunol.1800597] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 09/17/2018] [Indexed: 12/13/2022]
Abstract
Zika virus (ZIKV) outbreaks pose a massive public health threat in several countries. We have developed an in vivo model to investigate the host-ZIKV interaction in Drosophila We have found that a strain of ZIKV replicates in wild-type flies without reducing their survival ability. We have shown that ZIKV infection triggers RNA interference and that mutating Dicer-2 results in enhanced ZIKV load and increased susceptibility to ZIKV infection. Using a flavivirus-specific Ab, we have found that ZIKV is localized in the gut and fat body cells of the infected wild-type flies and results in their perturbed homeostasis. In addition, Dicer-2 mutants display severely reduced insulin activity, which could contribute toward the increased mortality of these flies. Our work establishes the suitability of Drosophila as the model system to study host-ZIKV dynamics, which is expected to greatly advance our understanding of the molecular and physiological processes that determine the outcome of this disease.
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Affiliation(s)
- Sneh Harsh
- Department of Biological Sciences, The Institute for Biomedical Sciences, The George Washington University, Washington, DC 20052; and
| | - Yaprak Ozakman
- Department of Biological Sciences, The Institute for Biomedical Sciences, The George Washington University, Washington, DC 20052; and
| | - Shannon M Kitchen
- Department of Microbiology, Immunology, and Tropical Medicine, GW School of Medicine & Health Sciences, The George Washington University, Washington, DC 20052
| | - Dominic Paquin-Proulx
- Department of Microbiology, Immunology, and Tropical Medicine, GW School of Medicine & Health Sciences, The George Washington University, Washington, DC 20052
| | - Douglas F Nixon
- Department of Microbiology, Immunology, and Tropical Medicine, GW School of Medicine & Health Sciences, The George Washington University, Washington, DC 20052
| | - Ioannis Eleftherianos
- Department of Biological Sciences, The Institute for Biomedical Sciences, The George Washington University, Washington, DC 20052; and
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Leggewie M, Schnettler E. RNAi-mediated antiviral immunity in insects and their possible application. Curr Opin Virol 2018; 32:108-114. [DOI: 10.1016/j.coviro.2018.10.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/16/2018] [Accepted: 10/23/2018] [Indexed: 01/09/2023]
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Aedes Anphevirus: an Insect-Specific Virus Distributed Worldwide in Aedes aegypti Mosquitoes That Has Complex Interplays with Wolbachia and Dengue Virus Infection in Cells. J Virol 2018; 92:JVI.00224-18. [PMID: 29950416 DOI: 10.1128/jvi.00224-18] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 05/30/2018] [Indexed: 01/21/2023] Open
Abstract
Insect-specific viruses (ISVs) of the yellow fever mosquito Aedes aegypti have been demonstrated to modulate transmission of arboviruses such as dengue virus (DENV) and West Nile virus by the mosquito. The diversity and composition of the virome of A. aegypti, however, remains poorly understood. In this study, we characterized Aedes anphevirus (AeAV), a negative-sense RNA virus from the order Mononegavirales AeAV identified from Aedes cell lines was infectious to both A. aegypti and Aedes albopictus cells but not to three mammalian cell lines. To understand the incidence and genetic diversity of AeAV, we assembled 17 coding-complete and two partial genomes of AeAV from available transcriptome sequencing (RNA-Seq) data. AeAV appears to transmit vertically and be present in laboratory colonies, wild-caught mosquitoes, and cell lines worldwide. Phylogenetic analysis of AeAV strains indicates that as the A. aegypti mosquito has expanded into the Americas and Asia-Pacific, AeAV has evolved into monophyletic African, American, and Asia-Pacific lineages. The endosymbiotic bacterium Wolbachia pipientis restricts positive-sense RNA viruses in A. aegypti Reanalysis of a small RNA library of A. aegypti cells coinfected with AeAV and Wolbachia produces an abundant RNA interference (RNAi) response consistent with persistent virus replication. We found Wolbachia enhances replication of AeAV compared to a tetracycline-cleared cell line, and AeAV modestly reduces DENV replication in vitro The results from our study improve understanding of the diversity and evolution of the virome of A. aegypti and adds to previous evidence that shows Wolbachia does not restrict a range of negative-strand RNA viruses.IMPORTANCE The mosquito Aedes aegypti transmits a number of arthropod-borne viruses (arboviruses), such as dengue virus and Zika virus. Mosquitoes also harbor insect-specific viruses that may affect replication of pathogenic arboviruses in their body. Currently, however, there are only a few insect-specific viruses described from A. aegypti in the literature. Here, we characterize a novel negative-strand virus, AeAV. Meta-analysis of A. aegypti samples showed that it is present in A. aegypti mosquitoes worldwide and is vertically transmitted. Wolbachia-transinfected mosquitoes are currently being used in biocontrol, as they effectively block transmission of several positive-sense RNA viruses in mosquitoes. Our results demonstrate that Wolbachia enhances the replication of AeAV and modestly reduces dengue virus replication in a cell line model. This study expands our understanding of the virome in A. aegypti as well as providing insight into the complexity of the Wolbachia virus restriction phenotype.
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Spindle-E Acts Antivirally Against Alphaviruses in Mosquito Cells. Viruses 2018; 10:v10020088. [PMID: 29463033 PMCID: PMC5850395 DOI: 10.3390/v10020088] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 02/14/2018] [Accepted: 02/15/2018] [Indexed: 12/11/2022] Open
Abstract
Mosquitoes transmit several human- and animal-pathogenic alphaviruses (Togaviridae family). In alphavirus-infected mosquito cells two different types of virus-specific small RNAs are produced as part of the RNA interference response: short-interfering (si)RNAs and PIWI-interacting (pi)RNAs. The siRNA pathway is generally thought to be the main antiviral pathway. Although an antiviral activity has been suggested for the piRNA pathway its role in host defences is not clear. Knock down of key proteins of the piRNA pathway (Ago3 and Piwi5) in Aedes aegypti-derived cells reduced the production of alphavirus chikungunya virus (CHIKV)-specific piRNAs but had no effect on virus replication. In contrast, knock down of the siRNA pathway key protein Ago2 resulted in an increase in virus replication. Similar results were obtained when expression of Piwi4 was silenced. Knock down of the helicase Spindle-E (SpnE), an essential co-factor of the piRNA pathway in Drosophila melanogaster, resulted in increased virus replication indicating that SpnE acts as an antiviral against alphaviruses such as CHIKV and the related Semliki Forest virus (SFV). Surprisingly, this effect was found to be independent of the siRNA and piRNA pathways in Ae. aegypti cells and specific for alphaviruses. This suggests a small RNA-independent antiviral function for this protein in mosquitoes.
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Mosquitoes as Arbovirus Vectors: From Species Identification to Vector Competence. PARASITOLOGY RESEARCH MONOGRAPHS 2018. [PMCID: PMC7122353 DOI: 10.1007/978-3-319-94075-5_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Mosquitoes and other arthropods transmit a large number of medically important pathogens, in particular viruses. These arthropod-borne viruses (arboviruses) include a wide variety of RNA viruses belonging to the Flaviviridae family (West Nile virus (WNV), Usutu virus (USUV), Dengue virus (DENV), Japanese encephalitis virus (JEV), Zika virus (ZIKV)), the Togaviridae family (Chikungunya virus (CHIKV)), and Bunyavirales order (Rift Valley fever virus (RVFV)) (please refer also to Table 9.1). Arboviral transmission to humans and livestock constitutes a major threat to public health and economy as illustrated by the emergence of ZIKV in the Americas, RVFV outbreaks in Africa, and the worldwide outbreaks of DENV. To answer the question if those viral pathogens also pose a risk to Europe, we need to first answer the key questions (summarized in Fig. 9.1):Who could contribute to such an outbreak? Information about mosquito species resident or imported, potential hosts and viruses able to infect vectors and hosts in Germany is needed. Where would competent mosquito species meet favorable conditions for transmission? Information on the minimum requirements for efficient replication of the virus in a given vector species and subsequent transmission is needed. How do viruses and vectors interact to facilitate transmission? Information on the vector immunity, vector physiology, vector genetics, and vector microbiomes is needed.
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Varjak M, Donald CL, Mottram TJ, Sreenu VB, Merits A, Maringer K, Schnettler E, Kohl A. Characterization of the Zika virus induced small RNA response in Aedes aegypti cells. PLoS Negl Trop Dis 2017; 11:e0006010. [PMID: 29040304 PMCID: PMC5667879 DOI: 10.1371/journal.pntd.0006010] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 11/02/2017] [Accepted: 10/04/2017] [Indexed: 01/16/2023] Open
Abstract
RNA interference (RNAi) controls arbovirus infections in mosquitoes. Two different RNAi pathways are involved in antiviral responses: the PIWI-interacting RNA (piRNA) and exogenous short interfering RNA (exo-siRNA) pathways, which are characterized by the production of virus-derived small RNAs of 25–29 and 21 nucleotides, respectively. The exo-siRNA pathway is considered to be the key mosquito antiviral response mechanism. In Aedes aegypti-derived cells, Zika virus (ZIKV)-specific siRNAs were produced and loaded into the exo-siRNA pathway effector protein Argonaute 2 (Ago2); although the knockdown of Ago2 did not enhance virus replication. Enhanced ZIKV replication was observed in a Dcr2-knockout cell line suggesting that the exo-siRNA pathway is implicated in the antiviral response. Although ZIKV-specific piRNA-sized small RNAs were detected, these lacked the characteristic piRNA ping-pong signature motif and were bound to Ago3 but not Piwi5 or Piwi6. Silencing of PIWI proteins indicated that the knockdown of Ago3, Piwi5 or Piwi6 did not enhance ZIKV replication and only Piwi4 displayed antiviral activity. We also report that the expression of ZIKV capsid (C) protein amplified the replication of a reporter alphavirus; although, unlike yellow fever virus C protein, it does not inhibit the exo-siRNA pathway. Our findings elucidate ZIKV-mosquito RNAi interactions that are important for understanding its spread. The recent outbreak of Zika virus (ZIKV) in the Americas has resulted in a severe threat to public health. ZIKV is transmitted by Aedes aegypti mosquitoes, thus it is important to understand virus-vector interactions. Analysis of ZIKV infection in mosquito cells indicated that two RNA interference pathways are involved during infection: the exogenous short-interfering (si)RNA (exo-siRNA) and PIWI-interacting (pi)RNA pathways. If Dcr2, an enzyme responsible for cleaving dsRNA into siRNAs, is knocked out, ZIKV replication is increased compared to control cells. However, the knockdown of Ago2 expression had no significant enhancing effect on ZIKV replication. In the case of the PIWI pathway, only the Piwi4 protein was found to have significant antiviral activity. Furthermore, unlike the capsid (C) protein of yellow fever virus, ZIKV capsid protein does not suppress the siRNA pathway. These results suggest that ZIKV has mechanisms to evade mosquito innate immunity and it is therefore important to understand these virus-vector interactions and the implications they have on transmission.
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Affiliation(s)
- Margus Varjak
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
- * E-mail: (MV); (AK)
| | - Claire L. Donald
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Timothy J. Mottram
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Vattipally B. Sreenu
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Andres Merits
- Institute of Technology, University of Tartu, Nooruse 1, Tartu, Estonia
| | - Kevin Maringer
- Department of Microbial Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Esther Schnettler
- Bernhard-Nocht-Institute for Tropical Medicine, Bernhard-Nocht-Strasse, Hamburg, Germany
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
- * E-mail: (MV); (AK)
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Lee M, Etebari K, Hall-Mendelin S, van den Hurk AF, Hobson-Peters J, Vatipally S, Schnettler E, Hall R, Asgari S. Understanding the role of microRNAs in the interaction of Aedes aegypti mosquitoes with an insect-specific flavivirus. J Gen Virol 2017; 98:1892-1903. [PMID: 28699859 DOI: 10.1099/jgv.0.000832] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Flavivirus genus contains some of the most prevalent vector-borne viruses, such as the dengue, Zika and yellow fever viruses that cause devastating diseases in humans. However, the insect-specific clade of flaviviruses is restricted to mosquito hosts, albeit they have retained the general features of the genus, such as genome structure and replication. The interactions between insect-specific flaviviruses (ISFs) and their mosquito hosts are largely unknown. Pathogenic flaviviruses are known to modulate host-derived microRNAs (miRNAs), a class of non-coding RNAs that are important in controlling gene expression. Alterations in miRNAs may represent changes in host gene expression and promote understanding of virus-host interactions. The role of miRNAs in ISF-mosquito interactions is largely unknown. A recently discovered Australian ISF, Palm Creek virus (PCV), has the ability to suppress medically relevant flaviviruses. Here, we investigated the potential involvement of miRNAs in PCV infection using the model mosquito Aedes aegypti. By combining small-RNA sequencing and bioinformatics analysis, differentially expressed miRNAs were determined. Our results indicated that PCV infection hardly affects host miRNAs. Out of 101 reported miRNAs of Ae. aegypti, only aae-miR-2940-5p had a significantly altered expression over the course of infection. However, further analysis of aae-miR-2940-5p revealed that this miRNA does not have any direct impact on PCV replication in vitro. Thus, overall the results suggest that PCV infection has a limited effect on the mosquito miRNA profile and therefore miRNAs may not play a significant role in the PCV-Ae. aegypti interaction.
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Affiliation(s)
- Morris Lee
- Australian Infectious Disease Research Centre, School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kayvan Etebari
- Australian Infectious Disease Research Centre, School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Sonja Hall-Mendelin
- Public Health Virology, Forensic and Scientific Services, Department of Health, Queensland Government, PO Box 594, Archerfield, QLD 4108, Australia
| | - Andrew F van den Hurk
- Public Health Virology, Forensic and Scientific Services, Department of Health, Queensland Government, PO Box 594, Archerfield, QLD 4108, Australia
| | - Jody Hobson-Peters
- Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Sreenu Vatipally
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, Scotland, UK
| | - Esther Schnettler
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, Scotland, UK
- Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Germany
| | - Roy Hall
- Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Sassan Asgari
- Australian Infectious Disease Research Centre, School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
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RNA Interference Restricts Rift Valley Fever Virus in Multiple Insect Systems. mSphere 2017; 2:mSphere00090-17. [PMID: 28497117 PMCID: PMC5415632 DOI: 10.1128/msphere.00090-17] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 03/31/2017] [Indexed: 01/03/2023] Open
Abstract
The emerging bunyavirus Rift Valley fever virus (RVFV) is transmitted to humans and livestock by a large number of mosquito species. RNA interference (RNAi) has been characterized as an important innate immune defense mechanism used by mosquitoes to limit replication of positive-sense RNA flaviviruses and togaviruses; however, little is known about its role against negative-strand RNA viruses such as RVFV. We show that virus-specific small RNAs are produced in infected mosquito cells, in Drosophila melanogaster cells, and, most importantly, also in RVFV vector mosquitoes. By addressing the production of small RNAs in adult Aedes sp. and Culex quinquefasciatus mosquitoes, we showed the presence of virus-derived Piwi-interacting RNAs (piRNAs) not only in Aedes sp. but also in C. quinquefasciatus mosquitoes, indicating that antiviral RNA interference in C. quinquefasciatus mosquitoes is similar to the described activities of RNAi in Aedes sp. mosquitoes. We also show that these have antiviral activity, since silencing of RNAi pathway effectors enhances viral replication. Moreover, our data suggest that RVFV does not encode a suppressor of RNAi. These findings point toward a significant role of RNAi in the control of RVFV in mosquitoes. IMPORTANCE Rift Valley fever virus (RVFV; Phlebovirus, Bunyaviridae) is an emerging zoonotic mosquito-borne pathogen of high relevance for human and animal health. Successful strategies of intervention in RVFV transmission by its mosquito vectors and the prevention of human and veterinary disease rely on a better understanding of the mechanisms that govern RVFV-vector interactions. Despite its medical importance, little is known about the factors that govern RVFV replication, dissemination, and transmission in the invertebrate host. Here we studied the role of the antiviral RNA interference immune pathways in the defense against RVFV in natural vector mosquitoes and mosquito cells and draw comparisons to the model insect Drosophila melanogaster. We found that RVFV infection induces both the exogenous small interfering RNA (siRNA) and piRNA pathways, which contribute to the control of viral replication in insects. Furthermore, we demonstrate the production of virus-derived piRNAs in Culex quinquefasciatus mosquitoes. Understanding these pathways and the targets within them offers the potential of the development of novel RVFV control measures in vector-based strategies.
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Varjak M, Maringer K, Watson M, Sreenu VB, Fredericks AC, Pondeville E, Donald CL, Sterk J, Kean J, Vazeille M, Failloux AB, Kohl A, Schnettler E. Aedes aegypti Piwi4 Is a Noncanonical PIWI Protein Involved in Antiviral Responses. mSphere 2017; 2:e00144-17. [PMID: 28497119 PMCID: PMC5415634 DOI: 10.1128/msphere.00144-17] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 04/12/2017] [Indexed: 11/20/2022] Open
Abstract
The small interfering RNA (siRNA) pathway is a major antiviral response in mosquitoes; however, another RNA interference pathway, the PIWI-interacting RNA (piRNA) pathway, has been suggested to be antiviral in mosquitoes. Piwi4 has been reported to be a key mediator of this response in mosquitoes, but it is not involved in the production of virus-specific piRNAs. Here, we show that Piwi4 associates with members of the antiviral exogenous siRNA pathway (Ago2 and Dcr2), as well as with proteins of the piRNA pathway (Ago3, Piwi5, and Piwi6) in an Aedes aegypti-derived cell line, Aag2. Analysis of small RNAs captured by Piwi4 revealed that it is predominantly associated with virus-specific siRNAs in Semliki Forest virus-infected cells and, to a lesser extent, with viral piRNAs. By using a Dcr2 knockout cell line, we showed directly that Ago2 lost its antiviral activity, as it was no longer bound to siRNAs, but Piwi4 retained its antiviral activity in the absence of the siRNA pathway. These results demonstrate a complex interaction between the siRNA and piRNA pathways in A. aegypti and identify Piwi4 as a noncanonical PIWI protein that interacts with members of the siRNA and piRNA pathways, and its antiviral activities may be independent of either pathway. IMPORTANCE Mosquitoes transmit several pathogenic viruses, for example, the chikungunya and Zika viruses. In mosquito cells, virus replication intermediates in the form of double-stranded RNA are cleaved by Dcr2 into 21-nucleotide-long siRNAs, which in turn are used by Ago2 to target the virus genome. A different class of virus-derived small RNAs, PIWI-interacting RNAs (piRNAs), have also been found in infected insect cells. These piRNAs are longer and are produced in a Dcr2-independent manner. The only known antiviral protein in the PIWI family is Piwi4, which is not involved in piRNA production. It is associated with key proteins of the siRNA and piRNA pathways, although its antiviral function is independent of their actions.
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Affiliation(s)
- Margus Varjak
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Kevin Maringer
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Mick Watson
- Roslin Institute, University of Edinburgh, Edinburgh, Scotland
| | | | - Anthony C. Fredericks
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Emilie Pondeville
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Claire L. Donald
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Jelle Sterk
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Joy Kean
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Marie Vazeille
- Arboviruses and Insect Vectors Unit, Department of Virology, Institut Pasteur, Paris, France
| | - Anna-Bella Failloux
- Arboviruses and Insect Vectors Unit, Department of Virology, Institut Pasteur, Paris, France
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
| | - Esther Schnettler
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland
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