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Bosch-Camós L, Martínez-Torró C, López-Laguna H, Lascorz J, Argilaguet J, Villaverde A, Rodríguez F, Vázquez E. Nanoparticle-Based Secretory Granules Induce a Specific and Long-Lasting Immune Response through Prolonged Antigen Release. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:435. [PMID: 38470766 DOI: 10.3390/nano14050435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/22/2024] [Accepted: 02/26/2024] [Indexed: 03/14/2024]
Abstract
Developing prolonged antigen delivery systems that mimic long-term exposure to pathogens appears as a promising but still poorly explored approach to reach durable immunities. In this study, we have used a simple technology by which His-tagged proteins can be assembled, assisted by divalent cations, as supramolecular complexes with progressive complexity, namely protein-only nanoparticles and microparticles. Microparticles produced out of nanoparticles are biomimetics of secretory granules from the mammalian hormonal system. Upon subcutaneous administration, they slowly disintegrate, acting as an endocrine-like secretory system and rendering the building block nanoparticles progressively bioavailable. The performance of such materials, previously validated for drug delivery in oncology, has been tested here regarding the potential for time-prolonged antigen release. This has been completed by taking, as a building block, a nanostructured version of p30, a main structural immunogen from the African swine fever virus (ASFV). By challenging the system in both mice and pigs, we have observed unusually potent pro-inflammatory activity in porcine macrophages, and long-lasting humoral and cellular responses in vivo, which might overcome the need for an adjuvant. The robustness of both innate and adaptive responses tag, for the first time, these dynamic depot materials as a novel and valuable instrument with transversal applicability in immune stimulation and vaccinology.
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Affiliation(s)
- Laia Bosch-Camós
- Unitat Mixta d'Investigació IRTA-UAB en Sanitat Animal, Centre de Recerca en Sanitat Animal (CReSA), Campus de la Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Spain
- Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Programa de Sanitat Animal, Centre de Recerca en Sanitat Animal (CReSA), Campus de la Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Spain
- WOAH Collaborating Centre for the Research and Control of Emerging and Re-Emerging Swine Diseases in Europe (IRTA-CReSA), 08193 Bellaterra, Spain
| | - Carlos Martínez-Torró
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN, ISCIII), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Hèctor López-Laguna
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN, ISCIII), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Jara Lascorz
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN, ISCIII), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Jordi Argilaguet
- Unitat Mixta d'Investigació IRTA-UAB en Sanitat Animal, Centre de Recerca en Sanitat Animal (CReSA), Campus de la Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Spain
- Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Programa de Sanitat Animal, Centre de Recerca en Sanitat Animal (CReSA), Campus de la Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Spain
- WOAH Collaborating Centre for the Research and Control of Emerging and Re-Emerging Swine Diseases in Europe (IRTA-CReSA), 08193 Bellaterra, Spain
| | - Antonio Villaverde
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN, ISCIII), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Fernando Rodríguez
- Unitat Mixta d'Investigació IRTA-UAB en Sanitat Animal, Centre de Recerca en Sanitat Animal (CReSA), Campus de la Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Spain
- Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Programa de Sanitat Animal, Centre de Recerca en Sanitat Animal (CReSA), Campus de la Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Spain
- WOAH Collaborating Centre for the Research and Control of Emerging and Re-Emerging Swine Diseases in Europe (IRTA-CReSA), 08193 Bellaterra, Spain
| | - Esther Vázquez
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN, ISCIII), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
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Minch B, Akter S, Weinheimer A, Rahman MS, Parvez MAK, Rezwana Rahman S, Ahmed MF, Moniruzzaman M. Phylogenetic diversity and functional potential of large and cell-associated viruses in the Bay of Bengal. mSphere 2023; 8:e0040723. [PMID: 37902318 PMCID: PMC10732071 DOI: 10.1128/msphere.00407-23] [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: 07/19/2023] [Accepted: 09/22/2023] [Indexed: 10/31/2023] Open
Abstract
IMPORTANCE The BoB, the world's largest bay, is of significant economic importance to surrounding countries, particularly Bangladesh, which heavily relies on its coastal resources. Concurrently, the BoB holds substantial ecological relevance due to the region's high vulnerability to climate change-induced impacts. Yet, our understanding of the BoB's microbiome in relation to marine food web and biogeochemical cycling remains limited. Particularly, there are little or no data on the viral diversity and host association in the BoB. We examined the viral community in two distinct BoB coastal regions to reveal a multitude of viral species interacting with a wide range of microbial hosts, some of which play key roles in coastal biogeochemical cycling or potential pathogens. Furthermore, we demonstrate that the BoB coast harbors a diverse community of large and giant viruses, underscoring the importance of investigating understudied environments to discover novel viral lineages with complex metabolic capacities.
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Affiliation(s)
- Benjamin Minch
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, Miami, Florida, USA
| | - Salma Akter
- Department of Microbiology, Jahangirnagar University, Dhaka, Bangladesh
| | | | - M. Shaminur Rahman
- Department of Microbiology, Jashore University of Science and Technology, Jashore, Bangladesh
| | | | | | - Md Firoz Ahmed
- Department of Microbiology, Jahangirnagar University, Dhaka, Bangladesh
| | - Mohammad Moniruzzaman
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, Miami, Florida, USA
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Esmael A, Agarkova IV, Dunigan DD, Zhou Y, Van Etten JL. Viral DNA Accumulation Regulates Replication Efficiency of Chlorovirus OSy-NE5 in Two Closely Related Chlorella variabilis Strains. Viruses 2023; 15:1341. [PMID: 37376640 DOI: 10.3390/v15061341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023] Open
Abstract
Many chloroviruses replicate in Chlorella variabilis algal strains that are ex-endosymbionts isolated from the protozoan Paramecium bursaria, including the NC64A and Syngen 2-3 strains. We noticed that indigenous water samples produced a higher number of plaque-forming viruses on C. variabilis Syngen 2-3 lawns than on C. variabilis NC64A lawns. These observed differences led to the discovery of viruses that replicate exclusively in Syngen 2-3 cells, named Only Syngen (OSy) viruses. Here, we demonstrate that OSy viruses initiate infection in the restricted host NC64A by synthesizing some early virus gene products and that approximately 20% of the cells produce a small number of empty virus capsids. However, the infected cells did not produce infectious viruses because the cells were unable to replicate the viral genome. This is interesting because all previous attempts to isolate host cells resistant to chlorovirus infection were due to changes in the host receptor for the virus.
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Affiliation(s)
- Ahmed Esmael
- Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583, USA
- Botany and Microbiology Department, Faculty of Science, Benha University, Benha 13518, Egypt
| | - Irina V Agarkova
- Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583, USA
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583, USA
| | - David D Dunigan
- Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583, USA
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583, USA
| | - You Zhou
- Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - James L Van Etten
- Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583, USA
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583, USA
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Lobb B, Shapter A, Doxey AC, Nissimov JI. Functional Profiling and Evolutionary Analysis of a Marine Microalgal Virus Pangenome. Viruses 2023; 15:v15051116. [PMID: 37243202 DOI: 10.3390/v15051116] [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: 01/12/2023] [Accepted: 05/04/2023] [Indexed: 05/28/2023] Open
Abstract
Phycodnaviridae are large double-stranded DNA viruses, which facilitate studies of host-virus interactions and co-evolution due to their prominence in algal infection and their role in the life cycle of algal blooms. However, the genomic interpretation of these viruses is hampered by a lack of functional information, stemming from the surprising number of hypothetical genes of unknown function. It is also unclear how many of these genes are widely shared within the clade. Using one of the most extensively characterized genera, Coccolithovirus, as a case study, we combined pangenome analysis, multiple functional annotation tools, AlphaFold structural modeling, and literature analysis to compare the core and accessory pangenome and assess support for novel functional predictions. We determined that the Coccolithovirus pangenome shares 30% of its genes with all 14 strains, making up the core. Notably, 34% of its genes were found in at most three strains. Core genes were enriched in early expression based on a transcriptomic dataset of Coccolithovirus EhV-201 algal infection, were more likely to be similar to host proteins than the non-core set, and were more likely to be involved in vital functions such as replication, recombination, and repair. In addition, we generated and collated annotations for the EhV representative EhV-86 from 12 different annotation sources, building up information for 142 previously hypothetical and putative membrane proteins. AlphaFold was further able to predict structures for 204 EhV-86 proteins with a modelling accuracy of good-high. These functional clues, combined with generated AlphaFold structures, provide a foundational framework for the future characterization of this model genus (and other giant viruses) and a further look into the evolution of the Coccolithovirus proteome.
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Affiliation(s)
- Briallen Lobb
- Department of Biology, University of Waterloo, 200 University Ave. West., Waterloo, ON N2L 3G1, Canada
| | - Anson Shapter
- Department of Biology, University of Waterloo, 200 University Ave. West., Waterloo, ON N2L 3G1, Canada
| | - Andrew C Doxey
- Department of Biology, University of Waterloo, 200 University Ave. West., Waterloo, ON N2L 3G1, Canada
| | - Jozef I Nissimov
- Department of Biology, University of Waterloo, 200 University Ave. West., Waterloo, ON N2L 3G1, Canada
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Correia S, Moura PL, Ventura S, Leitão A, Parkhouse RME. I329L: A Dual Action Viral Antagonist of TLR Activation Encoded by the African Swine Fever Virus (ASFV). Viruses 2023; 15:445. [PMID: 36851659 PMCID: PMC9965916 DOI: 10.3390/v15020445] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/28/2023] [Accepted: 02/01/2023] [Indexed: 02/09/2023] Open
Abstract
The African Swine Fever Virus (ASFV) is an economically important, large DNA virus which causes a highly contagious and frequently fatal disease in domestic pigs. Due to the acute nature of the infection and the complexity of the protective porcine anti-ASFV response, there is no accepted vaccine in use. As resistance to ASFV is known to correlate with a robust IFN response, the virus is predicted to have evolved strategies to inhibit innate immunity by modulating the IFN response. The deletion of virus host evasion gene(s) inhibiting IFN is a logical solution to develop an attenuated virus vaccine. One such candidate, the ASFV ORF I329L gene, is highly conserved in pathogenic and non-pathogenic virus isolates and in this study we confirm and extend the conclusion that it has evolved for the inhibition of innate immunity initiated through Toll-like receptors (TLRs). Specifically, the ASFV I329L extracellular (ECD) and intracellular (ICD) domains inhibit TLR signalling by two entirely different mechanisms. Bioinformatics modelling suggests that the ECD inhibits several TLR signalling pathways through a short sequence homologous to the conserved TLR dimerization domain, here termed the putative dimerization domain (PDD). Remarkably, both full length and PDD constructs of I329L were demonstrated to inhibit activation, not only of TLR3, but also TLR4, TLR5, TLR8 and TLR9. Additionally, the demonstration of a weak association of I329L with TLR3 is consistent with the formation of a non-signalling I329L-TLR3 heterodimer, perhaps mediated through the PDD of I329L. Finally, the ICD associates with TRIF, thereby impacting on both TLR3 and TLR4 signalling. Thus, I329L offers potential as a general inhibitor of TLR responses and is a rational candidate for construction and testing of an I329L deletion mutant vaccine.
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Affiliation(s)
- Sílvia Correia
- Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
- CIISA—Centro de Investigação Interdisciplinar em Sanidade Animal, Faculdade de Medicina Veterinária, Universidade de Lisboa, 1300-477 Lisbon, Portugal
- Laboratório Associado para Ciência Animal e Veterinária (AL4AnimalS), 1300-477 Lisbon, Portugal
| | | | - Sónia Ventura
- Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
| | - Alexandre Leitão
- CIISA—Centro de Investigação Interdisciplinar em Sanidade Animal, Faculdade de Medicina Veterinária, Universidade de Lisboa, 1300-477 Lisbon, Portugal
- Laboratório Associado para Ciência Animal e Veterinária (AL4AnimalS), 1300-477 Lisbon, Portugal
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ÇAKAR B, TOMRUK C, ÇELİK S, UYANIKGİL Y. Rejeneratif tıpta model organizma; Aksolotl (Ambystoma Mexicanum). EGE TIP DERGISI 2022. [DOI: 10.19161/etd.1086385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Wang Y, Cui S, Xin T, Wang X, Yu H, Chen S, Jiang Y, Gao X, Jiang Y, Guo X, Jia H, Zhu H. African Swine Fever Virus MGF360-14L Negatively Regulates Type I Interferon Signaling by Targeting IRF3. Front Cell Infect Microbiol 2022; 11:818969. [PMID: 35096660 PMCID: PMC8790226 DOI: 10.3389/fcimb.2021.818969] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 12/22/2021] [Indexed: 12/16/2022] Open
Abstract
African swine fever (ASF) is a devastating infectious disease caused by African swine fever virus (ASFV). The ASFV genome encodes multiple structural and non-structural proteins that contribute to evasion of host immunity. In this study, we determined that the viral non-structural protein MGF360-14L inhibits interferon-β (IFN-β) promoter activity induced by cGAS-STING signaling. MGF360-14L was also found to downregulate expression of the IRF3 protein and promote its degradation through ubiquitin-meditated proteolysis. Moreover, MGF360-14L was shown to interact with and destabilize IRF3 by facilitating E3 ligase TRIM21-mediated K63-linked ubiquitination of IRF3. Overall, our study revealed that MGF360-14L promotes degradation of IRF3 through TRIM21, thereby inhibiting type I interferon production. These findings provide new insights into the mechanisms underlying ASFV immune evasion.
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Affiliation(s)
- Yang Wang
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Shuai Cui
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Ting Xin
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xixi Wang
- Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing, China
| | - Hainan Yu
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Shiyu Chen
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yajun Jiang
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xintao Gao
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
| | - Yitong Jiang
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiaoyu Guo
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Hong Jia
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Hongfei Zhu
- Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
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Chaivisuthangkura P, Longyant S, Sithigorngul P. Immunological-based assays for specific detection of shrimp viruses. World J Virol 2014; 3:1-10. [PMID: 24567913 PMCID: PMC3926971 DOI: 10.5501/wjv.v3.i1.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 10/25/2013] [Accepted: 11/16/2013] [Indexed: 02/05/2023] Open
Abstract
Among shrimp viral pathogens, white spot syndrome virus (WSSV) and yellow head virus (YHV) are the most lethal agents, causing serious problems for both the whiteleg shrimp, Penaeus (Litopenaeus) vannamei, and the black tiger shrimp, Penaeus (Penaeus) monodon. Another important virus that infects P. vannamei is infectious myonecrosis virus (IMNV), which induces the white discoloration of affected muscle. In the cases of taura syndrome virus and Penaeus stylirostris densovirus (PstDNV; formerly known as infectious hypodermal and hematopoietic necrosis virus), their impacts were greatly diminished after the introduction of tolerant stocks of P. vannamei. Less important viruses are Penaeus monodon densovirus (PmDNV; formerly called hepatopancreatic parvovirus), and Penaeus monodon nucleopolyhedrovirus (PemoNPV; previously called monodon baculovirus). For freshwater prawn, Macrobrachium rosenbergii nodavirus and extra small virus are considered important viral pathogens. Monoclonal antibodies (MAbs) specific to the shrimp viruses described above have been generated and used as an alternative tool in various immunoassays such as enzyme-linked immunosorbent assay, dot blotting, Western blotting and immunohistochemistry. Some of these MAbs were further developed into immunochromatographic strip tests for the detection of WSSV, YHV, IMNV and PemoNPV and into a dual strip test for the simultaneous detection of WSSV/YHV. The strip test has the advantages of speed, as the result can be obtained within 15 min, and simplicity, as laboratory equipment and specialized skills are not required. Therefore, strip tests can be used by shrimp farmers for the pond-side monitoring of viral infection.
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He Y, Zhang X. Comprehensive characterization of viral miRNAs involved in white spot syndrome virus (WSSV) infection. RNA Biol 2012; 9:1019-29. [PMID: 22832246 DOI: 10.4161/rna.20741] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Guided by miRNAs, RNAi plays an important role in virus-host interactions by fine-tuning gene expression. Many viral and cellular miRNAs are involved in virus infection, though no comprehensive general model for miRNAs derived from invertebrate DNA viruses exists for their function in eukaryotic systems, despite extensive research on miRNAs. To address this issue, the miRNAs from shrimp white spot syndrome virus (WSSV), a DNA virus with a 305 kb double-stranded circular DNA genome, were characterized. Based on WSSV miRNA microarray and northern blot analyses, WSSV was shown to possess the capacity to encode 40 distinct viral miRNAs, a miRNA content roughly 360 times greater than that of humans. These findings suggested that the high content of viral miRNAs might greatly contribute to viral variability in response selective pressures in the host environment. Transcription analysis revealed that 80% of WSSV miRNAs were expressed during early stages of viral infection, indicating their importance in initial infective processes. Additionally, biogenesis of viral miRNAs was demonstrated to be dependent on host Drosha and Dicer 1, mediated by Ago 1, and viral miRNAs, including WSSV-miR211 and WSSV-miR212, were required for successful WSSV infection. During WSSV infection, numerous viral genes were likely targeted by WSSV miRNAs. The current study presented the first comprehensive view of viral miRNAs encoded by an invertebrate DNA virus, providing insight into the molecular events of virus-host interactions.
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Affiliation(s)
- Yaodong He
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, Key Laboratory of Animal Virology of Ministry of Agriculture and College of Life Sciences, Zhejiang University, Hangzhou, China
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Abstract
Because viruses of eukaryotic algae are incredibly diverse, sweeping generalizations about their ecology are rare. These obligate parasites infect a range of algae and their diversity can be illustrated by considering that isolates range from small particles with ssRNA genomes to much larger particles with 560 kb dsDNA genomes. Molecular research has also provided clues about the extent of their diversity especially considering that genetic signatures of algal viruses in the environment rarely match cultivated viruses. One general concept in algal virus ecology that has emerged is that algal viruses are very host specific and most infect only certain strains of their hosts; with the exception of viruses of brown algae, evidence for interspecies infectivity is lacking. Although some host-virus systems behave with boom-bust oscillations, complex patterns of intraspecies infectivity can lead to host-virus coexistence obfuscating the role of viruses in host population dynamics. Within the framework of population dynamics, host density dependence is an important phenomenon that influences virus abundances in nature. Variable burst sizes of different viruses also influence their abundances and permit speculations about different life strategies, but as exceptions are common in algal virus ecology, life strategy generalizations may not be broadly applicable. Gaps in knowledge of virus seasonality and persistence are beginning to close and investigations of environmental reservoirs and virus resilience may answer questions about virus inter-annual recurrences. Studies of algal mortality have shown that viruses are often important agents of mortality reinforcing notions about their ecological relevance, while observations of the surprising ways viruses interact with their hosts highlight the immaturity of our understanding. Considering that just two decades ago algal viruses were hardly acknowledged, recent progress affords the optimistic perspective that future studies will provide keys to unlocking our understanding of algal virus ecology specifically, and aquatic ecosystems generally.
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Affiliation(s)
- Steven M Short
- Department of Biology, University of Toronto Mississauga, Mississauga, Canada.
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11
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Abstract
Viruses with genomes greater than 300 kb and up to 1200 kb are being discovered with increasing frequency. These large viruses (often called giruses) can encode up to 900 proteins and also many tRNAs. Consequently, these viruses have more protein-encoding genes than many bacteria, and the concept of small particle/small genome that once defined viruses is no longer valid. Giruses infect bacteria and animals although most of the recently discovered ones infect protists. Thus, genome gigantism is not restricted to a specific host or phylogenetic clade. To date, most of the giruses are associated with aqueous environments. Many of these large viruses (phycodnaviruses and Mimiviruses) probably have a common evolutionary ancestor with the poxviruses, iridoviruses, asfarviruses, ascoviruses, and a recently discovered Marseillevirus. One issue that is perhaps not appreciated by the microbiology community is that large viruses, even ones classified in the same family, can differ significantly in morphology, lifestyle, and genome structure. This review focuses on some of these differences than on extensive details about individual viruses.
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Affiliation(s)
- James L Van Etten
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583, USA.
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