1
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Schinkel M, Bousema T, van Rij RP. Tripartite interactions between viruses, parasites, and mosquitoes. CURRENT OPINION IN INSECT SCIENCE 2024; 64:101222. [PMID: 38908822 DOI: 10.1016/j.cois.2024.101222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 06/13/2024] [Accepted: 06/13/2024] [Indexed: 06/24/2024]
Abstract
Mosquito-borne diseases have a major impact on global human health. Biological agents that colonize the mosquito vector are increasingly explored as an intervention strategy to prevent vector-borne disease transmission. For instance, the release of mosquitoes carrying the endosymbiotic bacterium Wolbachia effectively reduced dengue virus incidence and disease. Insect-specific viruses are likewise considered as biocontrol agents against vector-borne diseases. While most studies focused on insect-specific viruses as an intervention against arthropod-borne viruses, we here consider whether mosquito-specific viruses may affect the transmission of the malaria-causing Plasmodium parasite by Anopheles mosquitoes. Although there is no direct experimental evidence addressing this question, we found that viral infections in dipteran insects activate some of the immune pathways that are antiparasitic in Anopheles. These findings suggest that indirect virus-parasite interactions could occur and that insect-specific viruses may modulate malaria transmission. Tripartite interactions between viruses, parasites, and Anopheles mosquitoes thus merit further investigation.
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Affiliation(s)
- Michelle Schinkel
- Department of Medical Microbiology, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, the Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, the Netherlands
| | - Ronald P van Rij
- Department of Medical Microbiology, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, the Netherlands.
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2
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Hu D, Xu F, Gao Z, Chen K, Guo W, Wang Z, Li S, Feng C. Pleiotropic immunoregulation by growth-blocking peptide in Ostrinia furnacalis. INSECT MOLECULAR BIOLOGY 2024; 33:270-282. [PMID: 38329162 DOI: 10.1111/imb.12898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 01/20/2024] [Indexed: 02/09/2024]
Abstract
Insects rely on their innate immune system to eliminate pathogenic microbes. As a system component, cytokines transmit intercellular signals to control immune responses. Growth-blocking peptide (GBP) is a member of the stress-responsive peptide family of cytokines found in several orders of insects, including Drosophila. However, the physiological role of GBP in defence against pathogens is not thoroughly understood. In this study, we explored the functions of GBP in a lepidopteran pest, Ostrinia furnacalis. Injection of recombinant O. furnacalis GBP (OfGBP) precursor (proGBP) and chemically synthesised GBP significantly induced the transcription of antimicrobial peptides (AMPs) and other immunity-related genes including immune deficiency (IMD) and Dorsal. The level of OfGBP mRNA was upregulated after bacterial infection. Knockdown of OfGBP expression led to a decrease in IMD, Relish, MyD88 and Dorsal mRNA levels. OfGBP induced phenoloxidase activity and affected hemocyte behaviours in O. furnacalis larvae. In summary, GBP is a potent cytokine, effectively regulating AMP synthesis, melanization response and cellular immunity to eliminate invading pathogens.
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Affiliation(s)
- Dongchun Hu
- Department of Entomology, College of Plant Protection, Yangzhou University, Yangzhou, China
| | - Fuqiang Xu
- Department of Entomology, College of Plant Protection, Yangzhou University, Yangzhou, China
| | - Zupeng Gao
- Department of Entomology, College of Plant Protection, Yangzhou University, Yangzhou, China
| | - Kangkang Chen
- Department of Entomology, College of Plant Protection, Yangzhou University, Yangzhou, China
| | - Wenlong Guo
- Department of Entomology, College of Plant Protection, Yangzhou University, Yangzhou, China
| | - Zitian Wang
- Department of Entomology, College of Plant Protection, Yangzhou University, Yangzhou, China
| | - Shuzhong Li
- Department of Entomology, College of Plant Protection, Yangzhou University, Yangzhou, China
| | - Congjing Feng
- Department of Entomology, College of Plant Protection, Yangzhou University, Yangzhou, China
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3
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Zhang J, Zafar J, Kong J, Wang F, Shao X, Zhang R, Pang R, Xu H, Xu X, Jin F. MicroRNA-Mediated Host Immune Genes Manipulation Benefits AcMNPV Proliferation in Spodoptera frugiperda. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71. [PMID: 37917564 PMCID: PMC10655178 DOI: 10.1021/acs.jafc.3c05012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/10/2023] [Accepted: 10/12/2023] [Indexed: 11/04/2023]
Abstract
Spodoptera frugiperda is a highly destructive migratory pest that threatens various crops globally. Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is an effective biocontrol agent against lepidopteran pests. Here, we explored the molecular mechanisms underlying the immune response to AcMNPV infection in S. frugiperda. RNA-seq and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analyses identified the Toll, IMD, and apoptosis pathways as primary immune responses. Investigation into AcMNPV-induced apoptosis in the S. frugiperda cell line (Sf9) revealed that the Toll pathway activated the JNK via the TRAF6 (TNF receptor-associated factor 6) adapter. In addition, AcMNPV-induced the differential expression of several host-encoded microRNAs (miRNAs), with significant negative regulatory effects, on S. frugiperda antiviral immune genes. RNAi and miRNA-mimic mediated silencing of these genes resulted in increased AcMNPV proliferation. Our findings reinforce the potential of AcMNPV as a potent biocontrol agent and further our understanding of developing biotechnology-based targeted pest control agents.
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Affiliation(s)
- Jie Zhang
- National
Key Laboratory of Green Pesticide, “Belt and Road” Technology
Industry and Innovation Institute for Green and Biological Control
of Agricultural Pests, College of Plant
Protection, South China Agricultural University, Guangzhou 510642, China
| | - Junaid Zafar
- National
Key Laboratory of Green Pesticide, “Belt and Road” Technology
Industry and Innovation Institute for Green and Biological Control
of Agricultural Pests, College of Plant
Protection, South China Agricultural University, Guangzhou 510642, China
| | - Jinrong Kong
- National
Key Laboratory of Green Pesticide, “Belt and Road” Technology
Industry and Innovation Institute for Green and Biological Control
of Agricultural Pests, College of Plant
Protection, South China Agricultural University, Guangzhou 510642, China
| | - Fei Wang
- National
Key Laboratory of Green Pesticide, “Belt and Road” Technology
Industry and Innovation Institute for Green and Biological Control
of Agricultural Pests, College of Plant
Protection, South China Agricultural University, Guangzhou 510642, China
| | - Xuehua Shao
- Institute
of Fruit Tree Research, Guangdong Academy of Agricultural Sciences,
Key Laboratory of South Subtropical Fruit Biology and Genetic Resource
Utilization, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Tropical and
Subtropical Fruit Tree Research, Guangzhou 510640, China
| | - Ruonan Zhang
- National
Key Laboratory of Green Pesticide, “Belt and Road” Technology
Industry and Innovation Institute for Green and Biological Control
of Agricultural Pests, College of Plant
Protection, South China Agricultural University, Guangzhou 510642, China
| | - Rui Pang
- National
Key Laboratory of Green Pesticide, “Belt and Road” Technology
Industry and Innovation Institute for Green and Biological Control
of Agricultural Pests, College of Plant
Protection, South China Agricultural University, Guangzhou 510642, China
| | - Hanhong Xu
- National
Key Laboratory of Green Pesticide, “Belt and Road” Technology
Industry and Innovation Institute for Green and Biological Control
of Agricultural Pests, College of Plant
Protection, South China Agricultural University, Guangzhou 510642, China
| | - Xiaoxia Xu
- National
Key Laboratory of Green Pesticide, “Belt and Road” Technology
Industry and Innovation Institute for Green and Biological Control
of Agricultural Pests, College of Plant
Protection, South China Agricultural University, Guangzhou 510642, China
| | - Fengliang Jin
- National
Key Laboratory of Green Pesticide, “Belt and Road” Technology
Industry and Innovation Institute for Green and Biological Control
of Agricultural Pests, College of Plant
Protection, South China Agricultural University, Guangzhou 510642, China
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4
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Kuyateh O, Obbard DJ. Viruses in Laboratory Drosophila and Their Impact on Host Gene Expression. Viruses 2023; 15:1849. [PMID: 37766256 PMCID: PMC10537266 DOI: 10.3390/v15091849] [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: 07/09/2023] [Revised: 08/18/2023] [Accepted: 08/28/2023] [Indexed: 09/29/2023] Open
Abstract
Drosophila melanogaster has one of the best characterized antiviral immune responses among invertebrates. However, relatively few easily transmitted natural virus isolates are available, and so many Drosophila experiments have been performed using artificial infection routes and artificial host-virus combinations. These may not reflect natural infections, especially for subtle phenotypes such as gene expression. Here, to explore the laboratory virus community and to better understand how natural virus infections induce changes in gene expression, we have analysed seven publicly available D. melanogaster transcriptomic sequencing datasets that were originally sequenced for projects unrelated to virus infection. We have found ten known viruses-including five that have not been experimentally isolated-but no previously unknown viruses. Our analysis of host gene expression revealed that numerous genes were differentially expressed in flies that were naturally infected with a virus. For example, flies infected with nora virus showed patterns of gene expression consistent with intestinal vacuolization and possible host repair via the upd3 JAK/STAT pathway. We also found marked sex differences in virus-induced differential gene expression. Our results show that natural virus infection in laboratory Drosophila does indeed induce detectable changes in gene expression, suggesting that this may form an important background condition for experimental studies in the laboratory.
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Affiliation(s)
- Oumie Kuyateh
- Institute of Ecology and Evolution, University of Edinburgh, Ashworth Laboratories, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK;
- Parasites and Microbes, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Darren J. Obbard
- Institute of Ecology and Evolution, University of Edinburgh, Ashworth Laboratories, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK;
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5
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Mahanta DK, Bhoi TK, Komal J, Samal I, Nikhil RM, Paschapur AU, Singh G, Kumar PVD, Desai HR, Ahmad MA, Singh PP, Majhi PK, Mukherjee U, Singh P, Saini V, Shahanaz, Srinivasa N, Yele Y. Insect-pathogen crosstalk and the cellular-molecular mechanisms of insect immunity: uncovering the underlying signaling pathways and immune regulatory function of non-coding RNAs. Front Immunol 2023; 14:1169152. [PMID: 37691928 PMCID: PMC10491481 DOI: 10.3389/fimmu.2023.1169152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Accepted: 08/07/2023] [Indexed: 09/12/2023] Open
Abstract
Multicellular organisms are constantly subjected to pathogens that might be harmful. Although insects lack an adaptive immune system, they possess highly effective anti-infective mechanisms. Bacterial phagocytosis and parasite encapsulation are some forms of cellular responses. Insects often defend themselves against infections through a humoral response. This phenomenon includes the secretion of antimicrobial peptides into the hemolymph. Specific receptors for detecting infection are required for the recognition of foreign pathogens such as the proteins that recognize glucans and peptidoglycans, together referred to as PGRPs and βGRPs. Activation of these receptors leads to the stimulation of signaling pathways which further activates the genes encoding for antimicrobial peptides. Some instances of such pathways are the JAK-STAT, Imd, and Toll. The host immune response that frequently accompanies infections has, however, been circumvented by diseases, which may have assisted insects evolve their own complicated immune systems. The role of ncRNAs in insect immunology has been discussed in several notable studies and reviews. This paper examines the most recent research on the immune regulatory function of ncRNAs during insect-pathogen crosstalk, including insect- and pathogen-encoded miRNAs and lncRNAs, and provides an overview of the important insect signaling pathways and effector mechanisms activated by diverse pathogen invaders.
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Affiliation(s)
- Deepak Kumar Mahanta
- Department of Entomology, Dr. Rajendra Prasad Central Agricultural University, Samastipur, Bihar, India
| | - Tanmaya Kumar Bhoi
- Forest Protection Division, Indian Council of Forestry Research and Education (ICFRE) - Arid Forest Research Institute (ICFRE-AFRI), Jodhpur, Rajasthan, India
| | - J. Komal
- Department of Entomology, Navsari Agricultural University, Navsari, Gujarat, India
| | - Ipsita Samal
- ICAR-National Research Centre on Litchi, Mushahari, Ramna, Muzaffarpur, Bihar, India
| | - R. M. Nikhil
- Division of Entomology, Indian Agricultural Research Institute, New Delhi, India
| | - Amit Umesh Paschapur
- Crop Protection Division, Indian Council of Agricultural Research (ICAR)-Vivekananda Parvatiya Krishi Anusandhan Sansthan, Almora, Uttarakhand, India
| | - Gaurav Singh
- The Directorate of Research, Maharana Pratap Horticultural University, Karnal, Haryana, India
| | - P. V. Dinesh Kumar
- Department of Plant Pathology University of Agricultural Sciences, Bengaluru, Karnataka, India
| | - H. R. Desai
- Department of Entomology, Main Cotton Research Station, Navsari Agricultural University, Gujarat, India
| | - Mohammad Abbas Ahmad
- Department of Entomology, Dr. Rajendra Prasad Central Agricultural University, Samastipur, Bihar, India
| | - P. P. Singh
- Department of Entomology, Tirhut College of Agriculture, Dr. Rajendra Prasad Central Agricultural University, Samastipur, Bihar, India
| | - Prasanta Kumar Majhi
- Department of Plant Breeding and Genetics, Odisha University of Agriculture and Technology, Bhubaneswar, Odisha, India
| | - U. Mukherjee
- Department of Entomology, Dr. Rajendra Prasad Central Agricultural University, Samastipur, Bihar, India
| | - Pushpa Singh
- Department of Entomology, Dr. Rajendra Prasad Central Agricultural University, Samastipur, Bihar, India
| | - Varun Saini
- Department of Entomology, Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana, India
| | - Shahanaz
- Department of Entomology, College of Horticulture Mojerla, Sri Konda Laxman Telengana State Horticultural University, Wanaparthy, Telengana, India
| | - N. Srinivasa
- Department of Entomology and Agricultural Zoology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Yogesh Yele
- School of Crop Health Management Research, Council of Agricultural Research-National Institute of Biotic Stress Management (ICAR)- National Institute of Biotic Stress Management, Raipur, India
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6
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Unraveling the Role of Antimicrobial Peptides in Insects. Int J Mol Sci 2023; 24:ijms24065753. [PMID: 36982826 PMCID: PMC10059942 DOI: 10.3390/ijms24065753] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 03/14/2023] [Accepted: 03/15/2023] [Indexed: 03/19/2023] Open
Abstract
Antimicrobial peptides (AMPs) are short, mainly positively charged, amphipathic molecules. AMPs are important effectors of the immune response in insects with a broad spectrum of antibacterial, antifungal, and antiparasitic activity. In addition to these well-known roles, AMPs exhibit many other, often unobvious, functions in the host. They support insects in the elimination of viral infections. AMPs participate in the regulation of brain-controlled processes, e.g., sleep and non-associative learning. By influencing neuronal health, communication, and activity, they can affect the functioning of the insect nervous system. Expansion of the AMP repertoire and loss of their specificity is connected with the aging process and lifespan of insects. Moreover, AMPs take part in maintaining gut homeostasis, regulating the number of endosymbionts as well as reducing the number of foreign microbiota. In turn, the presence of AMPs in insect venom prevents the spread of infection in social insects, where the prey may be a source of pathogens.
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7
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Kietz C, Meinander A. Drosophila caspases as guardians of host-microbe interactions. Cell Death Differ 2023; 30:227-236. [PMID: 35810247 PMCID: PMC9950452 DOI: 10.1038/s41418-022-01038-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 06/22/2022] [Accepted: 06/22/2022] [Indexed: 11/09/2022] Open
Abstract
An intact cell death machinery is not only crucial for successful embryonic development and tissue homeostasis, but participates also in the defence against pathogens and contributes to a balanced immune response. Centrally involved in the regulation of both cell death and inflammatory immune responses is the evolutionarily conserved family of cysteine proteases named caspases. The Drosophila melanogaster genome encodes for seven caspases, several of which display dual functions, participating in apoptotic signalling and beyond. Among the Drosophila caspases, the caspase-8 homologue Dredd has a well-characterised role in inflammatory signalling activated by bacterial infections, and functions as a driver of NF-κB-mediated immune responses. Regarding the other Drosophila caspases, studies focusing on tissue-specific immune signalling and host-microbe interactions have recently revealed immunoregulatory functions of the initiator caspase Dronc and the effector caspase Drice. The aim of this review is to give an overview of the signalling cascades involved in the Drosophila humoral innate immune response against pathogens and of their caspase-mediated regulation. Furthermore, the apoptotic role of caspases during antibacterial and antiviral immune activation will be discussed.
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Affiliation(s)
- Christa Kietz
- Faculty of Science and Engineering, Cell Biology, Åbo Akademi University, BioCity, Turku, Finland
| | - Annika Meinander
- Faculty of Science and Engineering, Cell Biology, Åbo Akademi University, BioCity, Turku, Finland.
- InFLAMES Research Flagship Center, Åbo Akademi University, Turku, Finland.
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8
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Qiu JF, Cui WZ, Zhang Q, Dai TM, Liu K, Li JL, Wang YJ, Sima YH, Xu SQ. Temporal transcriptome reveals that circadian clock is involved in the dynamic regulation of immune response to bacterial infection in Bombyx mori. INSECT SCIENCE 2023; 30:31-46. [PMID: 35446483 DOI: 10.1111/1744-7917.13043] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 03/11/2022] [Accepted: 03/23/2022] [Indexed: 06/14/2023]
Abstract
The circadian clock plays a critical role in the regulation of host immune defense. However, the mechanistic basis for this regulation is largely unknown. Herein, the core clock gene cryptochrome1 (cry1) knockout line in Bombyx mori, an invertebrate animal model, was constructed to obtain the silkworm with dysfunctional molecular clock, and the dynamic regulation of the circadian clock on the immune responsiveness within 24 h of Staphylococcus aureus infection was analyzed. We found that deletion of cry1 decreased viability of silkworms and significantly reduced resistance of larvae to S. aureus. Time series RNA-seq analysis identified thousands of rhythmically expressed genes, including immune response genes, in the larval immune tissue, fat bodies. Uninfected cry1 knockout silkworms exhibited expression patterns of rhythmically expressed genes similar to wild-type (WT) silkworms infected with S. aureus. However, cry1 knockout silkworms exhibited a seriously weakened response to S. aureus infection. The immune response peaked at 6 and 24 h after infection, during which "transcription storms" occurred, and the expression levels of the immune response genes, PGRP and antimicrobial peptides (AMPs), were significantly upregulated in WT. In contrast, cry1 knockout did not effectively activate Toll, Imd, or NF-κB signaling pathways during the immune adjustment period from 12 to 18 h after infection, resulting in failure to initiate the immune responsiveness peak at 24 h after infection. This may be related to inhibited silkworm fat body energy metabolism. These results demonstrated the dynamic regulation of circadian clock on silkworm immune response to bacterial infection and provided important insights into host antimicrobial defense mechanisms.
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Affiliation(s)
- Jian-Feng Qiu
- School of Biology and Basic Medical Sciences, Suzhou Medical College, Soochow University, Suzhou, China, Jiangsu Province
- Institute of Agricultural Biotechnology & Ecology (IABE), Soochow University, Suzhou, China, Jiangsu Province
| | - Wen-Zhao Cui
- School of Biology and Basic Medical Sciences, Suzhou Medical College, Soochow University, Suzhou, China, Jiangsu Province
- Institute of Agricultural Biotechnology & Ecology (IABE), Soochow University, Suzhou, China, Jiangsu Province
| | - Qiang Zhang
- School of Biology and Basic Medical Sciences, Suzhou Medical College, Soochow University, Suzhou, China, Jiangsu Province
- Institute of Agricultural Biotechnology & Ecology (IABE), Soochow University, Suzhou, China, Jiangsu Province
| | - Tai-Ming Dai
- School of Biology and Basic Medical Sciences, Suzhou Medical College, Soochow University, Suzhou, China, Jiangsu Province
- Institute of Agricultural Biotechnology & Ecology (IABE), Soochow University, Suzhou, China, Jiangsu Province
| | - Kai Liu
- School of Biology and Basic Medical Sciences, Suzhou Medical College, Soochow University, Suzhou, China, Jiangsu Province
- Institute of Agricultural Biotechnology & Ecology (IABE), Soochow University, Suzhou, China, Jiangsu Province
| | - Jiang-Lan Li
- School of Biology and Basic Medical Sciences, Suzhou Medical College, Soochow University, Suzhou, China, Jiangsu Province
- Institute of Agricultural Biotechnology & Ecology (IABE), Soochow University, Suzhou, China, Jiangsu Province
| | - Yu-Jun Wang
- Guangxi Key Laboratory of Beibu Gulf Marine Biodiversity Conservation, College of Marine Sciences, Beibu Gulf University, Qinzhou, China, Guangxi Province
| | - Yang-Hu Sima
- School of Biology and Basic Medical Sciences, Suzhou Medical College, Soochow University, Suzhou, China, Jiangsu Province
- Institute of Agricultural Biotechnology & Ecology (IABE), Soochow University, Suzhou, China, Jiangsu Province
| | - Shi-Qing Xu
- School of Biology and Basic Medical Sciences, Suzhou Medical College, Soochow University, Suzhou, China, Jiangsu Province
- Institute of Agricultural Biotechnology & Ecology (IABE), Soochow University, Suzhou, China, Jiangsu Province
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9
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Stenglein MD. The Case for Studying New Viruses of New Hosts. Annu Rev Virol 2022; 9:157-172. [PMID: 35671564 DOI: 10.1146/annurev-virology-100220-112915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Virology has largely focused on viruses that are pathogenic to humans or to the other species that we care most about. There is no doubt that this has been a worthwhile investment. But many transformative advances have been made through the in-depth study of relatively obscure viruses that do not appear on lists of prioritized pathogens. In this review, I highlight the benefits that can accrue from the study of viruses and hosts off the beaten track. I take stock of viral sequence diversity across host taxa as an estimate of the bias that exists in our understanding of host-virus interactions. I describe the gains that have been made through the metagenomic discovery of thousands of new viruses in previously unsampled hosts as well as the limitations of metagenomic surveys. I conclude by suggesting that the study of viruses that naturally infect existing and emerging model organisms represents an opportunity to push virology forward in useful and hard to predict ways.Expected final online publication date for the Annual Review of Virology, Volume 9 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Mark D Stenglein
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA;
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10
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Zhang X, Xie J, Gao M, Yan Z, Chen L, Wei S, Feng R. Pseudorabies Virus ICP0 Abolishes Tumor Necrosis Factor Alpha-Induced NF-κB Activation by Degrading P65. Viruses 2022; 14:954. [PMID: 35632696 PMCID: PMC9142898 DOI: 10.3390/v14050954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 11/16/2022] Open
Abstract
Nuclear factor κB (NF-κB) is involved in a wide range of innate immune activities in host cells and serves as an important component of a host's immunity system. To survive in infected cells, viruses have evolved intricate strategies to evade the host immune response. Pseudorabies virus (PRV) is a member of the alpha herpesvirus family and is capable of causing reproductive and neurological dysfunction in pigs. PRV has a large DNA genome and therefore has the ability to encode numerous proteins that modulate host innate immune responses. In the present study, we demonstrated that the PRV-encoded immediate early protein ICP0 inhibits the tumor necrosis factor alpha (TNF-α)-mediated NF-κB signaling pathway. An in-depth study showed that ICP0 protein was able to limit NF-κB activation and decreased the expression of inflammatory cytokines interleukin-6 (IL-6) and interleukin 8 (IL-8). In addition, ICP0 blocked the activation of NF-κB through interacting with p65, degrading its protein expression and limiting its phosphorylation. PRV protein ICP0 is shown for the first time to enable escape from innate immune response through the regulation of NF-κB during PRV infection. These results illustrate that PRV ICP0 is able to block NF-κB activation. This mechanism may represent a critical role in the early events leading to PRV infection.
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Affiliation(s)
- Xiangbo Zhang
- Key Laboratory of Biotechnology and Bioengineering of State Ethnic Affairs Commission, Biomedical Research Center, Northwest Minzu University, Lanzhou 730030, China; (X.Z.); (J.X.); (Z.Y.); (L.C.)
| | - Jingying Xie
- Key Laboratory of Biotechnology and Bioengineering of State Ethnic Affairs Commission, Biomedical Research Center, Northwest Minzu University, Lanzhou 730030, China; (X.Z.); (J.X.); (Z.Y.); (L.C.)
- College of Life Science and Engineering, Northwest Minzu University, Lanzhou 730030, China;
| | - Ming Gao
- College of Life Science and Engineering, Northwest Minzu University, Lanzhou 730030, China;
| | - Zhenfang Yan
- Key Laboratory of Biotechnology and Bioengineering of State Ethnic Affairs Commission, Biomedical Research Center, Northwest Minzu University, Lanzhou 730030, China; (X.Z.); (J.X.); (Z.Y.); (L.C.)
| | - Lei Chen
- Key Laboratory of Biotechnology and Bioengineering of State Ethnic Affairs Commission, Biomedical Research Center, Northwest Minzu University, Lanzhou 730030, China; (X.Z.); (J.X.); (Z.Y.); (L.C.)
| | - Suocheng Wei
- College of Life Science and Engineering, Northwest Minzu University, Lanzhou 730030, China;
| | - Ruofei Feng
- Key Laboratory of Biotechnology and Bioengineering of State Ethnic Affairs Commission, Biomedical Research Center, Northwest Minzu University, Lanzhou 730030, China; (X.Z.); (J.X.); (Z.Y.); (L.C.)
- Gansu Tech Innovation Center of Animal Cell, Biomedical Research Center, Northwest Minzu University, Lanzhou 730030, China
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11
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Cheung YP, Park S, Pagtalunan J, Maringer K. The antiviral role of NF-κB-mediated immune responses and their antagonism by viruses in insects. J Gen Virol 2022; 103. [PMID: 35510990 DOI: 10.1099/jgv.0.001741] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The antiviral role of innate immune responses mediated by the NF-κB family of transcription factors is well established in vertebrates but was for a long time less clear in insects. Insects encode two canonical NF-κB pathways, the Toll and Imd ('immunodeficiency') pathways, which are best characterised for their role in antibacterial and antifungal defence. An increasing body of evidence has also implicated NF-κB-mediated innate immunity in antiviral responses against some, but not all, viruses. Specific pattern recognition receptors (PRRs) and molecular events leading to NF-κB activation by viral pathogen-associated molecular patterns (PAMPs) have been elucidated for a number of viruses and insect species. Particularly interesting are recent findings indicating that the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway detects viral RNA to activate NF-κB-regulated gene expression. We summarise the literature on virus-NF-κB pathway interactions across the class Insecta, with a focus on the dipterans Drosophila melanogaster and Aedes aegypti. We discuss potential reasons for differences observed between different virus-host combinations, and highlight similarities and differences between cGAS-STING signalling in insects versus vertebrates. Finally, we summarise the increasing number of known molecular mechanisms by which viruses antagonise NF-κB responses, which suggest that NF-κB-mediated immunity exerts strong evolutionary pressures on viruses. These developments in our understanding of insect antiviral immunity have relevance to the large number of insect species that impact on humans through their transmission of human, livestock and plant diseases, exploitation as biotechnology platforms, and role as parasites, pollinators, livestock and pests.
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Affiliation(s)
- Yin P Cheung
- The Pirbright Institute, Pirbright, Surrey, GU24 0NF, UK.,Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Sohyun Park
- The Pirbright Institute, Pirbright, Surrey, GU24 0NF, UK.,Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Justine Pagtalunan
- The Pirbright Institute, Pirbright, Surrey, GU24 0NF, UK.,Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Kevin Maringer
- The Pirbright Institute, Pirbright, Surrey, GU24 0NF, UK
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12
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Zhao S, Chen G, Kong X, Chen N, Wu X. BmNPV p35 Reduces the Accumulation of Virus-Derived siRNAs and Hinders the Function of siRNAs to Facilitate Viral Infection. Front Immunol 2022; 13:845268. [PMID: 35251046 PMCID: PMC8895250 DOI: 10.3389/fimmu.2022.845268] [Citation(s) in RCA: 3] [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: 12/29/2021] [Accepted: 01/25/2022] [Indexed: 11/25/2022] Open
Abstract
Antiviral immunity involves various mechanisms and responses, including the RNA interference (RNAi) pathway. During long-term coevolution, viruses have gained the ability to evade this defense by encoding viral suppressors of RNAi (VSRs). It was reported that p35 of baculovirus can inhibit cellular small interference RNA (siRNA) pathway; however, the molecular mechanisms underlying p35 as a VSR remain largely unclear. Here, we showed that p35 of Bombyx mori nucleopolyhedrovirus (BmNPV) reduces the accumulation of virus-derived siRNAs (vsiRNAs) mapped to a particular region in the viral genome, leading to an increased expression of the essential genes in this region, and revealed that p35 disrupts the function of siRNAs by preventing them from loading into Argonaute-2 (Ago2). This repressive effect on the cellular siRNA pathway enhances the replication of BmNPV. Thus, our findings illustrate for the first time the inhibitory mechanism of a baculovirus VSR and how this effect influences viral infection.
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Affiliation(s)
- Shudi Zhao
- College of Animal Sciences, Zhejiang University, Hangzhou, China
- Key Laboratory of Silkworm and Bee Resource Utilization and Innovation of Zhejiang Province, Hangzhou, China
| | - Guanping Chen
- College of Animal Sciences, Zhejiang University, Hangzhou, China
- Key Laboratory of Silkworm and Bee Resource Utilization and Innovation of Zhejiang Province, Hangzhou, China
| | - Xiangshuo Kong
- College of Animal Sciences, Zhejiang University, Hangzhou, China
- Key Laboratory of Silkworm and Bee Resource Utilization and Innovation of Zhejiang Province, Hangzhou, China
| | - Nan Chen
- College of Animal Sciences, Zhejiang University, Hangzhou, China
- Key Laboratory of Silkworm and Bee Resource Utilization and Innovation of Zhejiang Province, Hangzhou, China
| | - Xiaofeng Wu
- College of Animal Sciences, Zhejiang University, Hangzhou, China
- Key Laboratory of Silkworm and Bee Resource Utilization and Innovation of Zhejiang Province, Hangzhou, China
- *Correspondence: Xiaofeng Wu,
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13
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Sensing microbial infections in the Drosophila melanogaster genetic model organism. Immunogenetics 2022; 74:35-62. [DOI: 10.1007/s00251-021-01239-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 11/20/2021] [Indexed: 12/17/2022]
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14
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Etebari K, Gharuka M, Asgari S, Furlong MJ. Diverse Host Immune Responses of Different Geographical Populations of the Coconut Rhinoceros Beetle to Oryctes Rhinoceros Nudivirus (OrNV) Infection. Microbiol Spectr 2021; 9:e0068621. [PMID: 34523987 PMCID: PMC8557903 DOI: 10.1128/spectrum.00686-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 08/12/2021] [Indexed: 11/20/2022] Open
Abstract
Incursions of the coconut rhinoceros beetle (CRB), Oryctes rhinoceros, into different islands in the South Pacific have been detected in recent years. It has been suggested that this range expansion is related to an O. rhinoceros haplotype reported to show reduced susceptibility to the well-established classical biocontrol agent, Oryctes rhinoceros nudivirus (OrNV). Our understanding of the genetic characteristics which distinguish the population of O. rhinoceros that has recently established in Solomon Islands from other well-established populations across the region is very limited. Here, we hypothesized that the recently established O. rhinoceros population should have greater innate immune responses when challenged by OrNV than those of well-established and native O. rhinoceros populations. We used the RNA sequencing (RNA-Seq) approach to generate gene expression profiles of midgut tissue from OrNV-infected and noninfected individuals collected in the Solomon Islands (recent incursion), Papua New Guinea and Fiji (previously established), and the Philippines (within the native range). The collections included individuals from each of the three major mitochondrial lineages (CRB-G, CRB-PNG, and CRB-S) known to the region, allowing us to explore the specific responses of each haplotype to infection. Although insects from the Philippines and Solomon Islands that were tested belong to the same mitochondrial lineage (CRB-G), their overall responses to infection were different. The number of differentially expressed genes between OrNV-infected and noninfected wild-caught individuals from the four different locations varied from 148 to 252. Persistent OrNV infection caused a high level of induced antimicrobial activity and immune responses in O. rhinoceros, but the direction and magnitude of the responses were population specific. The insects tested from the Solomon Islands displayed extremely high expression of genes which are known to be involved in immune responses (e.g. coleoptericin, cecropin, and serpin). These variations in the host immune system among insects from different geographical regions might be driven by variations in the virulence of OrNV isolates, and this requires further investigation. Overall, our current findings support the importance of immunity in insect pest incursion and an expansion of the pest's geographic range. IMPORTANCE Oryctes rhinoceros nudivirus (OrNV) is a double-stranded DNA (dsDNA) virus which has been used as a biocontrol agent to suppress coconut rhinoceros beetle (CRB) in the Pacific Islands. Recently a new wave of CRB incursions in Oceania is thought to be related to the presence of low-virulence isolates of OrNV or virus-tolerant haplotypes of beetles (CRB-G). Our comparative analysis of OrNV-infected and noninfected CRBs revealed that specific sets of genes were induced by viral infection in the beetles. This induction was much stronger in beetles collected from the Solomon Islands, a newly invaded country, than in individuals collected from within the beetle's native range (the Philippines) or from longer-established populations in its exotic range (Fiji and Papua New Guinea [PNG]). Beetles from the Philippines and the Solomon Islands that were tested in this study all belonged to the CRB-G haplotype, but the country-specific responses of the beetles to OrNV infection were different.
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Affiliation(s)
- Kayvan Etebari
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Maria Gharuka
- Research Division, Ministry of Agriculture and Livestock, Honiara, Solomon Islands
| | - Sassan Asgari
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Michael J. Furlong
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
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15
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Roy M, Viginier B, Mayeux CA, Ratinier M, Fablet M. Infections by Transovarially Transmitted DMelSV in Drosophila Have No Impact on Ovarian Transposable Element Transcripts but Increase Their Amounts in the Soma. Genome Biol Evol 2021; 13:evab207. [PMID: 34498066 PMCID: PMC8459167 DOI: 10.1093/gbe/evab207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/01/2021] [Indexed: 12/21/2022] Open
Abstract
Transposable elements (TEs) are genomic parasites, which activity is tightly controlled in germline cells. Using Sindbis virus, it was recently demonstrated that viral infections affect TE transcript amounts in somatic tissues. However, the strongest evolutionary impacts are expected in gonads, because that is where the genomes of the next generations lie. Here, we investigated this aspect using the Drosophila melanogaster Sigma virus. It is particularly relevant in the genome/TE interaction given its tropism to ovaries, which is the organ displaying the more sophisticated TE control pathways. Our results in Drosophila simulans flies allowed us to confirm the existence of a strong homeostasis of the TE transcriptome in ovaries upon infection, which, however, rely on TE-derived small RNA modulations. In addition, we performed a meta-analysis of RNA-seq data and propose that the immune pathway that is triggered upon viral infection determines the direction of TE transcript modulation in somatic tissues.
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Affiliation(s)
- Marlène Roy
- Laboratoire de Biométrie et Biologie Evolutive, Université de Lyon, Université Lyon 1, CNRS, UMR 5558, Villeurbanne, France
- EPHE, PSL Research University, INRA, Université de Lyon, Université Claude Bernard Lyon1, UMR754, IVPC, Lyon, France
| | - Barbara Viginier
- EPHE, PSL Research University, INRA, Université de Lyon, Université Claude Bernard Lyon1, UMR754, IVPC, Lyon, France
| | - Camille A Mayeux
- Laboratoire de Biométrie et Biologie Evolutive, Université de Lyon, Université Lyon 1, CNRS, UMR 5558, Villeurbanne, France
| | - Maxime Ratinier
- EPHE, PSL Research University, INRA, Université de Lyon, Université Claude Bernard Lyon1, UMR754, IVPC, Lyon, France
| | - Marie Fablet
- Laboratoire de Biométrie et Biologie Evolutive, Université de Lyon, Université Lyon 1, CNRS, UMR 5558, Villeurbanne, France
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16
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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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17
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Schneider J, Imler JL. Sensing and signalling viral infection in drosophila. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 117:103985. [PMID: 33358662 DOI: 10.1016/j.dci.2020.103985] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/16/2020] [Accepted: 12/17/2020] [Indexed: 06/12/2023]
Abstract
The fruitfly Drosophila melanogaster is a valuable model to unravel mechanisms of innate immunity, in particular in the context of viral infections. RNA interference, and more specifically the small interfering RNA pathway, is a major component of antiviral immunity in drosophila. In addition, the contribution of inducible transcriptional responses to the control of viruses in drosophila and other invertebrates is increasingly recognized. In particular, the recent discovery of a STING-IKKβ-Relish signalling cassette in drosophila has confirmed that NF-κB transcription factors play an important role in the control of viral infections, in addition to bacterial and fungal infections. Here, we review recent developments in the field, which begin to shed light on the mechanisms involved in sensing of viral infections and in signalling leading to production of antiviral effectors.
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Affiliation(s)
- Juliette Schneider
- Université de Strasbourg, CNRS UPR9022, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
| | - Jean-Luc Imler
- Université de Strasbourg, CNRS UPR9022, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France; Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China.
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18
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Hill T, Unckless RL. Adaptation, ancestral variation and gene flow in a 'Sky Island' Drosophila species. Mol Ecol 2021; 30:83-99. [PMID: 33089581 PMCID: PMC7945764 DOI: 10.1111/mec.15701] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/28/2020] [Accepted: 10/08/2020] [Indexed: 02/06/2023]
Abstract
Over time, populations of species can expand, contract, fragment and become isolated, creating subpopulations that must adapt to local conditions. Understanding how species maintain variation after divergence as well as adapt to these changes in the face of gene flow is of great interest, especially as the current climate crisis has caused range shifts and frequent migrations for many species. Here, we characterize how a mycophageous fly species, Drosophila innubila, came to inhabit and adapt to its current range which includes mountain forests in south-western USA separated by large expanses of desert. Using population genomic data from more than 300 wild-caught individuals, we examine four populations to determine their population history in these mountain forests, looking for signatures of local adaptation. In this first extensive study, establishing D. innubila as a key genomic "Sky Island" model, we find D. innubila spread northwards during the previous glaciation period (30-100 KYA) and have recently expanded even further (0.2-2 KYA). D. innubila shows little evidence of population structure, consistent with a recent establishment and genetic variation maintained since before geographic stratification. We also find some signatures of recent selective sweeps in chorion proteins and population differentiation in antifungal immune genes suggesting differences in the environments to which flies are adapting. However, we find little support for long-term recurrent selection in these genes. In contrast, we find evidence of long-term recurrent positive selection in immune pathways such as the Toll signalling system and the Toll-regulated antimicrobial peptides.
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Affiliation(s)
- Tom Hill
- 4055 Haworth Hall, The Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS 66045
| | - Robert L. Unckless
- 4055 Haworth Hall, The Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS 66045
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19
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Wallace MA, Coffman KA, Gilbert C, Ravindran S, Albery GF, Abbott J, Argyridou E, Bellosta P, Betancourt AJ, Colinet H, Eric K, Glaser-Schmitt A, Grath S, Jelic M, Kankare M, Kozeretska I, Loeschcke V, Montchamp-Moreau C, Ometto L, Onder BS, Orengo DJ, Parsch J, Pascual M, Patenkovic A, Puerma E, Ritchie MG, Rota-Stabelli O, Schou MF, Serga SV, Stamenkovic-Radak M, Tanaskovic M, Veselinovic MS, Vieira J, Vieira CP, Kapun M, Flatt T, González J, Staubach F, Obbard DJ. The discovery, distribution, and diversity of DNA viruses associated with Drosophila melanogaster in Europe. Virus Evol 2021; 7:veab031. [PMID: 34408913 PMCID: PMC8363768 DOI: 10.1093/ve/veab031] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Drosophila melanogaster is an important model for antiviral immunity in arthropods, but very few DNA viruses have been described from the family Drosophilidae. This deficiency limits our opportunity to use natural host-pathogen combinations in experimental studies, and may bias our understanding of the Drosophila virome. Here, we report fourteen DNA viruses detected in a metagenomic analysis of 6668 pool-sequenced Drosophila, sampled from forty-seven European locations between 2014 and 2016. These include three new nudiviruses, a new and divergent entomopoxvirus, a virus related to Leptopilina boulardi filamentous virus, and a virus related to Musca domestica salivary gland hypertrophy virus. We also find an endogenous genomic copy of galbut virus, a double-stranded RNA partitivirus, segregating at very low frequency. Remarkably, we find that Drosophila Vesanto virus, a small DNA virus previously described as a bidnavirus, may be composed of up to twelve segments and thus represent a new lineage of segmented DNA viruses. Two of the DNA viruses, Drosophila Kallithea nudivirus and Drosophila Vesanto virus are relatively common, found in 2 per cent or more of wild flies. The others are rare, with many likely to be represented by a single infected fly. We find that virus prevalence in Europe reflects the prevalence seen in publicly available datasets, with Drosophila Kallithea nudivirus and Drosophila Vesanto virus the only ones commonly detectable in public data from wild-caught flies and large population cages, and the other viruses being rare or absent. These analyses suggest that DNA viruses are at lower prevalence than RNA viruses in D.melanogaster, and may be less likely to persist in laboratory cultures. Our findings go some way to redressing an earlier bias toward RNA virus studies in Drosophila, and lay the foundation needed to harness the power of Drosophila as a model system for the study of DNA viruses.
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Affiliation(s)
- Megan A Wallace
- The European Drosophila Population Genomics Consortium (DrosEU)
- Ashworth Laboratories, Institute of Evolutionary Biology, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Kelsey A Coffman
- Department of Entomology, University of Georgia, Athens, GA, USA
| | - Clément Gilbert
- The European Drosophila Population Genomics Consortium (DrosEU)
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Sanjana Ravindran
- Ashworth Laboratories, Institute of Evolutionary Biology, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Gregory F Albery
- Department of Biology, Georgetown University, Washington, DC, USA
| | - Jessica Abbott
- The European Drosophila Population Genomics Consortium (DrosEU)
- Department of Biology, Section for Evolutionary Ecology, Lund University, Sölvegatan 37, Lund 223 62, Sweden
| | - Eliza Argyridou
- The European Drosophila Population Genomics Consortium (DrosEU)
- Division of Evolutionary Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg, Germany
| | - Paola Bellosta
- The European Drosophila Population Genomics Consortium (DrosEU)
- Department of Cellular, Computational and Integrative Biology, CIBIO University of Trento, Via Sommarive 9, Trento 38123, Italy
- Department of Medicine & Endocrinology, NYU Langone Medical Center, 550 First Avenue, New York, NY 10016, USA
| | - Andrea J Betancourt
- The European Drosophila Population Genomics Consortium (DrosEU)
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Hervé Colinet
- The European Drosophila Population Genomics Consortium (DrosEU)
- UMR CNRS 6553 ECOBIO, Université de Rennes1, Rennes, France
| | - Katarina Eric
- The European Drosophila Population Genomics Consortium (DrosEU)
- Institute for Biological Research “Sinisa Stankovic”, National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, Belgrade, Serbia
| | - Amanda Glaser-Schmitt
- The European Drosophila Population Genomics Consortium (DrosEU)
- Division of Evolutionary Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg, Germany
| | - Sonja Grath
- The European Drosophila Population Genomics Consortium (DrosEU)
- Division of Evolutionary Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg, Germany
| | - Mihailo Jelic
- The European Drosophila Population Genomics Consortium (DrosEU)
- Faculty of Biology, University of Belgrade, Studentski trg 16, Belgrade, Serbia
| | - Maaria Kankare
- The European Drosophila Population Genomics Consortium (DrosEU)
- Department of Biological and Environmental Science, University of Jyväskylä, Finland
| | - Iryna Kozeretska
- The European Drosophila Population Genomics Consortium (DrosEU)
- National Antarctic Scientific Center of Ukraine, 16 Shevchenko Avenue, Kyiv, 01601, Ukraine
| | - Volker Loeschcke
- The European Drosophila Population Genomics Consortium (DrosEU)
- Department of Biology, Genetics, Ecology and Evolution, Aarhus University, Ny Munkegade 116, Aarhus C DK-8000, Denmark
| | - Catherine Montchamp-Moreau
- The European Drosophila Population Genomics Consortium (DrosEU)
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Lino Ometto
- The European Drosophila Population Genomics Consortium (DrosEU)
- Department of Biology and Biotechnology, University of Pavia, Pavia 27100, Italy
| | - Banu Sebnem Onder
- The European Drosophila Population Genomics Consortium (DrosEU)
- Department of Biology, Faculty of Science, Hacettepe University, Ankara, Turkey
| | - Dorcas J Orengo
- The European Drosophila Population Genomics Consortium (DrosEU)
- Departament de Genètica, Microbiologia i Estadística and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Barcelona, Spain
| | - John Parsch
- The European Drosophila Population Genomics Consortium (DrosEU)
- Division of Evolutionary Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg, Germany
| | - Marta Pascual
- The European Drosophila Population Genomics Consortium (DrosEU)
- Departament de Genètica, Microbiologia i Estadística and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Barcelona, Spain
| | - Aleksandra Patenkovic
- The European Drosophila Population Genomics Consortium (DrosEU)
- Institute for Biological Research “Sinisa Stankovic”, National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, Belgrade, Serbia
| | - Eva Puerma
- The European Drosophila Population Genomics Consortium (DrosEU)
- Departament de Genètica, Microbiologia i Estadística and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Barcelona, Spain
| | - Michael G Ritchie
- The European Drosophila Population Genomics Consortium (DrosEU)
- Centre for Biological Diversity, St Andrews University, St Andrews HY15 4SS, UK
| | - Omar Rota-Stabelli
- The European Drosophila Population Genomics Consortium (DrosEU)
- Research and Innovation Center, Fondazione E. Mach, San Michele all’Adige (TN) 38010, Italy
- Centre Agriculture Food Environment, University of Trento, San Michele all’Adige (TN) 38010, Italy
| | - Mads Fristrup Schou
- The European Drosophila Population Genomics Consortium (DrosEU)
- Department of Biology, Section for Evolutionary Ecology, Lund University, Sölvegatan 37, Lund 223 62, Sweden
- Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Svitlana V Serga
- The European Drosophila Population Genomics Consortium (DrosEU)
- National Antarctic Scientific Center of Ukraine, 16 Shevchenko Avenue, Kyiv, 01601, Ukraine
- Taras Shevchenko National University of Kyiv, 64 Volodymyrska str, Kyiv 01601, Ukraine
| | - Marina Stamenkovic-Radak
- The European Drosophila Population Genomics Consortium (DrosEU)
- Faculty of Biology, University of Belgrade, Studentski trg 16, Belgrade, Serbia
| | - Marija Tanaskovic
- The European Drosophila Population Genomics Consortium (DrosEU)
- Institute for Biological Research “Sinisa Stankovic”, National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, Belgrade, Serbia
| | - Marija Savic Veselinovic
- The European Drosophila Population Genomics Consortium (DrosEU)
- Faculty of Biology, University of Belgrade, Studentski trg 16, Belgrade, Serbia
| | - Jorge Vieira
- The European Drosophila Population Genomics Consortium (DrosEU)
- Instituto de Biologia Molecular e Celular (IBMC), University of Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, University of Porto, i3S, Porto, Portugal
| | - Cristina P Vieira
- The European Drosophila Population Genomics Consortium (DrosEU)
- Instituto de Biologia Molecular e Celular (IBMC), University of Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, University of Porto, i3S, Porto, Portugal
| | - Martin Kapun
- The European Drosophila Population Genomics Consortium (DrosEU)
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland
- Division of Cell & Developmental Biology, Medical University of Vienna, Vienna, Austria
| | - Thomas Flatt
- The European Drosophila Population Genomics Consortium (DrosEU)
- Department of Biology, University of Fribourg, Fribourg CH-1700, Switzerland
| | - Josefa González
- The European Drosophila Population Genomics Consortium (DrosEU)
- Institute of Evolutionary Biology (CSIC-UPF), Barcelona, Spain
| | - Fabian Staubach
- The European Drosophila Population Genomics Consortium (DrosEU)
- Department of Evolution and Ecology, University of Freiburg, Freiburg 79104, Germany
| | - Darren J Obbard
- The European Drosophila Population Genomics Consortium (DrosEU)
- Ashworth Laboratories, Institute of Evolutionary Biology, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
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20
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Hill T, Unckless RL. Recurrent evolution of high virulence in isolated populations of a DNA virus. eLife 2020; 9:e58931. [PMID: 33112738 PMCID: PMC7685711 DOI: 10.7554/elife.58931] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/28/2020] [Indexed: 12/30/2022] Open
Abstract
Hosts and viruses are constantly evolving in response to each other: as a host attempts to suppress a virus, the virus attempts to evade and suppress the host's immune system. Here, we describe the recurrent evolution of a virulent strain of a DNA virus, which infects multiple Drosophila species. Specifically, we identified two distinct viral types that differ 100-fold in viral titer in infected individuals, with similar differences observed in multiple species. Our analysis suggests that one of the viral types recurrently evolved at least four times in the past ~30,000 years, three times in Arizona and once in another geographically distinct species. This recurrent evolution may be facilitated by an effective mutation rate which increases as each prior mutation increases viral titer and effective population size. The higher titer viral type suppresses the host-immune system and an increased virulence compared to the low viral titer type.
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Affiliation(s)
- Tom Hill
- The Department of Molecular Biosciences, University of KansasLawrenceUnited States
| | - Robert L Unckless
- The Department of Molecular Biosciences, University of KansasLawrenceUnited States
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21
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Etebari K, Parry R, Beltran MJB, Furlong MJ. Transcription Profile and Genomic Variations of Oryctes Rhinoceros Nudivirus in Coconut Rhinoceros Beetles. J Virol 2020; 94:e01097-20. [PMID: 32878889 PMCID: PMC7592217 DOI: 10.1128/jvi.01097-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 08/25/2020] [Indexed: 12/21/2022] Open
Abstract
Oryctes rhinoceros nudivirus (OrNV) is a double-stranded DNA (dsDNA) virus which has been used as a biocontrol agent to suppress the coconut rhinoceros beetle (Oryctes rhinoceros) in Southeast Asia and the Pacific Islands. A new wave of O. rhinoceros incursions in Oceania is thought to be related to the presence of low-virulence isolates of OrNV or virus-tolerant haplotypes of beetles. In this study, chronically infected beetles were collected from Philippines, Fiji, Papua New Guinea (PNG), and the Solomon Islands (SI). RNA sequencing (RNA-seq) was performed to investigate the global viral gene expression profiles and for comparative genomic analysis of structural variations. Maximum likelihood phylogenic analysis indicated that OrNV strains from the SI and Philippines are closely related, while OrNV strains from PNG and Fiji formed a distinct adjacent clade. We detected several polymorphic sites with a frequency higher than 35% in 892 positions of the viral genome. Nonsynonymous mutations were detected in several hypothetical proteins and 15 nudivirus core genes, such as gp034, lef-8, lef-4, and vp91 We found limited evidence of variation in viral gene expression among geographic populations. Only a few genes, such as gp01, gp022, and gp107, were differentially expressed among different strains. Additionally, small RNA sequencing from the SI population suggested that OrNV is targeted by the host RNA interference (RNAi) response with abundant 21-nucleotide small RNAs. Some of these genomic changes are specific to the geographic population and could be related to particular phenotypic characteristics of the strain, such as viral pathogenicity or transmissibility, and this requires further investigation.IMPORTANCE Oryctes rhinoceros nudivirus has been an effective biocontrol agent against the coconut rhinoceros beetle in Southeast Asia and the Pacific Islands for decades. The recent outbreak of these beetles in many South Pacific islands has had a significant impact on livelihoods in the region. It has been suggested that the resurgence and spread of the pest are related to the presence of low-virulence isolates of OrNV or virus-tolerant haplotypes of beetles. We examined viral genomic and transcriptional variations in chronically infected beetles from different geographical populations. A high number of polymorphic sites among several geographical strains of OrNV were identified, but potentially only a few of these variations in the genome are involved in functional changes and can potentially alter the typical function. These findings provide valuable resources for future studies to improve our understanding of the OrNV genetic variations in different geographic regions and their potential link to virus pathogenicity.
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Affiliation(s)
- Kayvan Etebari
- School of Biological Sciences, The University of Queensland, Brisbane, Australia
| | - Rhys Parry
- School of Biological Sciences, The University of Queensland, Brisbane, Australia
| | - Marie Joy B Beltran
- National Crop Protection Centre, College of Agriculture and Food Science, University of the Philippines Los Baños College, Laguna, Philippines
| | - Michael J Furlong
- School of Biological Sciences, The University of Queensland, Brisbane, Australia
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22
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Feng M, Fei S, Xia J, Labropoulou V, Swevers L, Sun J. Antimicrobial Peptides as Potential Antiviral Factors in Insect Antiviral Immune Response. Front Immunol 2020; 11:2030. [PMID: 32983149 PMCID: PMC7492552 DOI: 10.3389/fimmu.2020.02030] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 07/27/2020] [Indexed: 12/17/2022] Open
Abstract
Antimicrobial peptides (AMPs) with antiviral activity (antiviral peptides: AVPs) have become a research hotspot and already show immense potential to become pharmaceutically available antiviral drugs. AVPs have exhibited huge potential in inhibiting viruses by targeting various stages of their life cycle. Insects are the most speciose group of animals that inhabit almost all ecosystems and habitats on the land and are a rich source of natural AMPs. However, insect AVP mining, functional research, and drug development are still in their infancy. This review aims to summarize the currently validated insect AVPs, explore potential new insect AVPs and to discuss their possible mechanism of synthesis and action, with a view to providing clues to unravel the mechanisms of insect antiviral immunity and to develop insect AVP-derived antiviral drugs.
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Affiliation(s)
- Min Feng
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China.,Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications, National Centre for Scientific Research Demokritos, Athens, Greece
| | - Shigang Fei
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Junming Xia
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Vassiliki Labropoulou
- Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications, National Centre for Scientific Research Demokritos, Athens, Greece
| | - Luc Swevers
- Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications, National Centre for Scientific Research Demokritos, Athens, Greece
| | - Jingchen Sun
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China
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23
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A DNA virus-encoded immune antagonist fully masks the potent antiviral activity of RNAi in Drosophila. Proc Natl Acad Sci U S A 2019; 116:24296-24302. [PMID: 31712431 DOI: 10.1073/pnas.1909183116] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Coevolution of viruses and their hosts may lead to viral strategies to avoid, evade, or suppress antiviral immunity. An example is antiviral RNA interference (RNAi) in insects: the host RNAi machinery processes viral double-stranded RNA into small interfering RNAs (siRNAs) to suppress viral replication, whereas insect viruses encode suppressors of RNAi, many of which inhibit viral small interfering RNA (vsiRNA) production. Yet, many studies have analyzed viral RNAi suppressors in heterologous systems, due to the lack of experimental systems to manipulate the viral genome of interest, raising questions about in vivo functions of RNAi suppressors. To address this caveat, we generated an RNAi suppressor-defective mutant of invertebrate iridescent virus 6 (IIV6), a large DNA virus in which we previously identified the 340R protein as a suppressor of RNAi. Loss of 340R did not affect vsiRNA production, indicating that 340R binds siRNA duplexes to prevent RNA-induced silencing complex assembly. Indeed, vsiRNAs were not efficiently loaded into Argonaute 2 during wild-type IIV6 infection. Moreover, IIV6 induced a limited set of mature microRNAs in a 340R-dependent manner, most notably miR-305-3p, which we attribute to stabilization of the miR-305-5p:3p duplex by 340R. The IIV6 340R deletion mutant did not have a replication defect in cells, but was strongly attenuated in adult Drosophila This in vivo replication defect was completely rescued in RNAi mutant flies, indicating that 340R is a bona fide RNAi suppressor, the absence of which uncovers a potent antiviral immune response that suppresses virus accumulation ∼100-fold. Together, our work indicates that viral RNAi suppressors may completely mask antiviral immunity.
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24
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Kenney E, Hawdon JM, O'Halloran D, Eleftherianos I. Heterorhabditis bacteriophora Excreted-Secreted Products Enable Infection by Photorhabdus luminescens Through Suppression of the Imd Pathway. Front Immunol 2019; 10:2372. [PMID: 31636642 PMCID: PMC6787769 DOI: 10.3389/fimmu.2019.02372] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 09/20/2019] [Indexed: 12/14/2022] Open
Abstract
Upon entering the hemocoel of its insect host, the entomopathogenic nematode Heterorhabditis bacteriophora releases its symbiotic bacteria Photorhabdus luminescens, which is also a strong insect pathogen. P. luminescens is known to suppress the insect immune response independently following its release, but the nematode appears to enact its own immunosuppressive mechanisms during the earliest phases of an infection. H. bacteriophora was found to produce a unique set of excreted-secreted proteins in response to host hemolymph, and while basal secretions are immunogenic with regard to Diptericin expression through the Imd pathway, host-induced secretions suppress this expression to a level below that of controls in Drosophila melanogaster. This effect is consistent in adults, larvae, and isolated larval fat bodies, and the magnitude of suppression is dose-dependent. By reducing the expression of Diptericin, an antimicrobial peptide active against Gram-negative bacteria, the activated excreted-secreted products enable a more rapid propagation of P. luminescens that corresponds to more rapid host mortality. The identification and isolation of the specific proteins responsible for this suppression represents an exciting field of study with potential for enhancing the biocontrol of insect pests and treatment of diseases associated with excessive inflammation.
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Affiliation(s)
- Eric Kenney
- Infection and Innate Immunity Lab, Department of Biological Sciences, George Washington University, Washington, DC, United States
| | - John M Hawdon
- Department of Microbiology, Immunology, and Tropical Medicine, George Washington University, Washington, DC, United States
| | - Damien O'Halloran
- Infection and Innate Immunity Lab, Department of Biological Sciences, George Washington University, Washington, DC, United States.,Institute for Neuroscience, Department of Biological Sciences, George Washington University, Washington, DC, United States
| | - Ioannis Eleftherianos
- Infection and Innate Immunity Lab, Department of Biological Sciences, George Washington University, Washington, DC, United States
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25
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Hill T, Koseva BS, Unckless RL. The Genome of Drosophila innubila Reveals Lineage-Specific Patterns of Selection in Immune Genes. Mol Biol Evol 2019; 36:1405-1417. [PMID: 30865231 PMCID: PMC6573480 DOI: 10.1093/molbev/msz059] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pathogenic microbes can exert extraordinary evolutionary pressure on their hosts. They can spread rapidly and sicken or even kill their host to promote their own proliferation. Because of this strong selective pressure, immune genes are some of the fastest evolving genes across metazoans, as highlighted in mammals and insects. Drosophila melanogaster serves as a powerful model for studying host/pathogen evolution. While Drosophila melanogaster are frequently exposed to various pathogens, little is known about D. melanogaster's ecology, or if they are representative of other Drosophila species in terms of pathogen pressure. Here, we characterize the genome of Drosophila innubila, a mushroom-feeding species highly diverged from D. melanogaster and investigate the evolution of the immune system. We find substantial differences in the rates of evolution of immune pathways between D. innubila and D. melanogaster. Contrasting what was previously found for D. melanogaster, we find little evidence of rapid evolution of the antiviral RNAi genes and high rates of evolution in the Toll pathway. This suggests that, while immune genes tend to be rapidly evolving in most species, the specific genes that are fastest evolving may depend either on the pathogens faced by the host and/or divergence in the basic architecture of the host's immune system.
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Affiliation(s)
- Tom Hill
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
| | | | - Robert L Unckless
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
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26
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West C, Rus F, Chen Y, Kleino A, Gangloff M, Gammon DB, Silverman N. IIV-6 Inhibits NF-κB Responses in Drosophila. Viruses 2019; 11:v11050409. [PMID: 31052481 PMCID: PMC6563256 DOI: 10.3390/v11050409] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 04/23/2019] [Accepted: 04/28/2019] [Indexed: 02/02/2023] Open
Abstract
The host immune response and virus-encoded immune evasion proteins pose constant, mutual selective pressure on each other. Virally encoded immune evasion proteins also indicate which host pathways must be inhibited to allow for viral replication. Here, we show that IIV-6 is capable of inhibiting the two Drosophila NF-κB signaling pathways, Imd and Toll. Antimicrobial peptide (AMP) gene induction downstream of either pathway is suppressed when cells infected with IIV-6 are also stimulated with Toll or Imd ligands. We find that cleavage of both Imd and Relish, as well as Relish nuclear translocation, three key points in Imd signal transduction, occur in IIV-6 infected cells, indicating that the mechanism of viral inhibition is farther downstream, at the level of Relish promoter binding or transcriptional activation. Additionally, flies co-infected with both IIV-6 and the Gram-negative bacterium, Erwinia carotovora carotovora, succumb to infection more rapidly than flies singly infected with either the virus or the bacterium. These findings demonstrate how pre-existing infections can have a dramatic and negative effect on secondary infections, and establish a Drosophila model to study confection susceptibility.
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Affiliation(s)
- Cara West
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Florentina Rus
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Ying Chen
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Anni Kleino
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Monique Gangloff
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK.
| | - Don B Gammon
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX T5390, USA.
| | - Neal Silverman
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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27
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Induction and Suppression of NF-κB Signalling by a DNA Virus of Drosophila. J Virol 2019; 93:JVI.01443-18. [PMID: 30404807 DOI: 10.1128/jvi.01443-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 10/29/2018] [Indexed: 12/12/2022] Open
Abstract
Interactions between the insect immune system and RNA viruses have been extensively studied in Drosophila, in which RNA interference, NF-κB, and JAK-STAT pathways underlie antiviral immunity. In response to RNA interference, insect viruses have convergently evolved suppressors of this pathway that act by diverse mechanisms to permit viral replication. However, interactions between the insect immune system and DNA viruses have received less attention, primarily because few Drosophila-infecting DNA virus isolates are available. In this study, we used a recently isolated DNA virus of Drosophila melanogaster, Kallithea virus (KV; family Nudiviridae), to probe known antiviral immune responses and virus evasion tactics in the context of DNA virus infection. We found that fly mutants for RNA interference and immune deficiency (Imd), but not Toll, pathways are more susceptible to Kallithea virus infection. We identified the Kallithea virus-encoded protein gp83 as a potent inhibitor of Toll signalling, suggesting that Toll mediates antiviral defense against Kallithea virus infection but that it is suppressed by the virus. We found that Kallithea virus gp83 inhibits Toll signalling through the regulation of NF-κB transcription factors. Furthermore, we found that gp83 of the closely related Drosophila innubila nudivirus (DiNV) suppresses D. melanogaster Toll signalling, suggesting an evolutionarily conserved function of Toll in defense against DNA viruses. Together, these results provide a broad description of known antiviral pathways in the context of DNA virus infection and identify the first Toll pathway inhibitor in a Drosophila virus, extending the known diversity of insect virus-encoded immune inhibitors.IMPORTANCE Coevolution of multicellular organisms and their natural viruses may lead to an intricate relationship in which host survival requires effective immunity and virus survival depends on evasion of such responses. Insect antiviral immunity and reciprocal virus immunosuppression tactics have been well studied in Drosophila melanogaster, primarily during RNA, but not DNA, virus infection. Therefore, we describe interactions between a recently isolated Drosophila DNA virus (Kallithea virus [KV]) and immune processes known to control RNA viruses, such as RNA interference (RNAi) and Imd pathways. We found that KV suppresses the Toll pathway and identified gp83 as a KV-encoded protein that underlies this suppression. This immunosuppressive ability is conserved in another nudivirus, suggesting that the Toll pathway has conserved antiviral activity against DNA nudiviruses, which have evolved suppressors in response. Together, these results indicate that DNA viruses induce and suppress NF-κB responses, and they advance the application of KV as a model to study insect immunity.
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