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Patel P, Nandi A, Verma SK, Kaushik N, Suar M, Choi EH, Kaushik NK. Zebrafish-based platform for emerging bio-contaminants and virus inactivation research. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 872:162197. [PMID: 36781138 PMCID: PMC9922160 DOI: 10.1016/j.scitotenv.2023.162197] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/23/2023] [Accepted: 02/08/2023] [Indexed: 05/27/2023]
Abstract
Emerging bio-contaminants such as viruses have affected health and environment settings of every country. Viruses are the minuscule entities resulting in severe contagious diseases like SARS, MERS, Ebola, and avian influenza. Recent epidemic like the SARS-CoV-2, the virus has undergone mutations strengthen them and allowing to escape from the remedies. Comprehensive knowledge of viruses is essential for the development of targeted therapeutic and vaccination treatments. Animal models mimicking human biology like non-human primates, rats, mice, and rabbits offer competitive advantage to assess risk of viral infections, chemical toxins, nanoparticles, and microbes. However, their economic maintenance has always been an issue. Furthermore, the redundancy of experimental results due to aforementioned aspects is also in examine. Hence, exploration for the alternative animal models is crucial for risk assessments. The current review examines zebrafish traits and explores the possibilities to monitor emerging bio-contaminants. Additionally, a comprehensive picture of the bio contaminant and virus particle invasion and abatement mechanisms in zebrafish and human cells is presented. Moreover, a zebrafish model to investigate the emerging viruses such as coronaviridae and poxviridae has been suggested.
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Affiliation(s)
- Paritosh Patel
- Plasma Bioscience Research Center, Department of Electrical and Biological Physics, Kwangwoon University, 01897 Seoul, South Korea
| | - Aditya Nandi
- School of Biotechnology, KIIT University, Bhubaneswar 751024, Odisha, India
| | - Suresh K Verma
- School of Biotechnology, KIIT University, Bhubaneswar 751024, Odisha, India; Condensed Matter Theory Group, Materials Theory Division, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
| | - Neha Kaushik
- Department of Biotechnology, College of Engineering, The University of Suwon, 18323 Hwaseong, Republic of Korea
| | - Mrutyunjay Suar
- School of Biotechnology, KIIT University, Bhubaneswar 751024, Odisha, India
| | - Eun Ha Choi
- Plasma Bioscience Research Center, Department of Electrical and Biological Physics, Kwangwoon University, 01897 Seoul, South Korea.
| | - Nagendra Kumar Kaushik
- Plasma Bioscience Research Center, Department of Electrical and Biological Physics, Kwangwoon University, 01897 Seoul, South Korea.
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Susceptibility and Permissivity of Zebrafish (Danio rerio) Larvae to Cypriniviruses. Viruses 2023; 15:v15030768. [PMID: 36992477 PMCID: PMC10051318 DOI: 10.3390/v15030768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 03/08/2023] [Accepted: 03/10/2023] [Indexed: 03/19/2023] Open
Abstract
The zebrafish (Danio rerio) represents an increasingly important model organism in virology. We evaluated its utility in the study of economically important viruses from the genus Cyprinivirus (anguillid herpesvirus 1, cyprinid herpesvirus 2 and cyprinid herpesvirus 3 (CyHV-3)). This revealed that zebrafish larvae were not susceptible to these viruses after immersion in contaminated water, but that infections could be established using artificial infection models in vitro (zebrafish cell lines) and in vivo (microinjection of larvae). However, infections were transient, with rapid viral clearance associated with apoptosis-like death of infected cells. Transcriptomic analysis of CyHV-3-infected larvae revealed upregulation of interferon-stimulated genes, in particular those encoding nucleic acid sensors, mediators of programmed cell death and related genes. It was notable that uncharacterized non-coding RNA genes and retrotransposons were also among those most upregulated. CRISPR/Cas9 knockout of the zebrafish gene encoding protein kinase R (PKR) and a related gene encoding a protein kinase containing Z-DNA binding domains (PKZ) had no impact on CyHV-3 clearance in larvae. Our study strongly supports the importance of innate immunity-virus interactions in the adaptation of cypriniviruses to their natural hosts. It also highlights the potential of the CyHV-3-zebrafish model, versus the CyHV-3-carp model, for study of these interactions.
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Hogan V, Johnson WE. Unique Structure and Distinctive Properties of the Ancient and Ubiquitous Gamma-Type Envelope Glycoprotein. Viruses 2023; 15:v15020274. [PMID: 36851488 PMCID: PMC9967133 DOI: 10.3390/v15020274] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/13/2023] [Accepted: 01/15/2023] [Indexed: 01/20/2023] Open
Abstract
After the onset of the AIDS pandemic, HIV-1 (genus Lentivirus) became the predominant model for studying retrovirus Env glycoproteins and their role in entry. However, HIV Env is an inadequate model for understanding entry of viruses in the Alpharetrovirus, Gammaretrovirus and Deltaretrovirus genera. For example, oncogenic model system viruses such as Rous sarcoma virus (RSV, Alpharetrovirus), murine leukemia virus (MLV, Gammaretrovirus) and human T-cell leukemia viruses (HTLV-I and HTLV-II, Deltaretrovirus) encode Envs that are structurally and functionally distinct from HIV Env. We refer to these as Gamma-type Envs. Gamma-type Envs are probably the most widespread retroviral Envs in nature. They are found in exogenous and endogenous retroviruses representing a broad spectrum of vertebrate hosts including amphibians, birds, reptiles, mammals and fish. In endogenous form, gamma-type Envs have been evolutionarily coopted numerous times, most notably as placental syncytins (e.g., human SYNC1 and SYNC2). Remarkably, gamma-type Envs are also found outside of the Retroviridae. Gp2 proteins of filoviruses (e.g., Ebolavirus) and snake arenaviruses in the genus Reptarenavirus are gamma-type Env homologs, products of ancient recombination events involving viruses of different Baltimore classes. Distinctive hallmarks of gamma-type Envs include a labile disulfide bond linking the surface and transmembrane subunits, a multi-stage attachment and fusion mechanism, a highly conserved (but poorly understood) "immunosuppressive domain", and activation by the viral protease during virion maturation. Here, we synthesize work from diverse retrovirus model systems to illustrate these distinctive properties and to highlight avenues for further exploration of gamma-type Env structure and function.
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Lee HJ, Hou Y, Maeng JH, Shah NM, Chen Y, Lawson HA, Yang H, Yue F, Wang T. Epigenomic analysis reveals prevalent contribution of transposable elements to cis-regulatory elements, tissue-specific expression, and alternative promoters in zebrafish. Genome Res 2022; 32:1424-1436. [PMID: 35649578 PMCID: PMC9341505 DOI: 10.1101/gr.276052.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Accepted: 05/27/2022] [Indexed: 12/04/2022]
Abstract
Transposable elements (TEs) encode regulatory elements that impact gene expression in multiple species, yet a comprehensive analysis of zebrafish TEs in the context of gene regulation is lacking. Here, we systematically investigate the epigenomic and transcriptomic landscape of TEs across 11 adult zebrafish tissues using multidimensional sequencing data. We find that TEs contribute substantially to a diverse array of regulatory elements in the zebrafish genome and that 37% of TEs are positioned in active regulatory states in adult zebrafish tissues. We identify TE subfamilies enriched in highly specific regulatory elements among different tissues. We use transcript assembly to discover TE-derived transcriptional units expressed across tissues. Finally, we show that novel TE-derived promoters can initiate tissue-specific transcription of alternate gene isoforms. This work provides a comprehensive profile of TE activity across normal zebrafish tissues, shedding light on mechanisms underlying the regulation of gene expression in this widely used model organism.
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Affiliation(s)
- Hyung Joo Lee
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Yiran Hou
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Ju Heon Maeng
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Nakul M Shah
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Yujie Chen
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Heather A Lawson
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Hongbo Yang
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | - Feng Yue
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois 60611, USA
| | - Ting Wang
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri 63108, USA
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Kim S, Vaidya B, Cho SY, Kwon J, Kim D. Human Norovirus-Induced Gene Expression Biomarkers in Zebrafish. J Food Prot 2022; 85:924-929. [PMID: 35333356 DOI: 10.4315/jfp-21-419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 03/16/2022] [Indexed: 11/11/2022]
Abstract
ABSTRACT The challenges associated with development of an animal model system to replicate human norovirus (HuNoV) has hampered the study of the pathogenesis and therapeutic interventions for this virus. In this study, we replicated HuNoV GII.4 and evaluated virus gene expression in infected zebrafish. Three doses of inoculation resulted in successful virus replication. Genes for transmembrane transporters (tfa, cftr, slc26a3, and slc26a6), a heat shock chaperone (hspa8), and immune response cytokines (ifng1 and il1b) were highly expressed in HuNoV-infected zebrafish; however, expression levels of genes were reduced in zebrafish infected with thermally inactivated HuNoV. These results confirm HuNoV replication in juvenile zebrafish and will facilitate the investigation of biomarker gene expression during HuNoV infection. HIGHLIGHTS
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Affiliation(s)
- Songhak Kim
- Department of Food Science and Technology and Foodborne Virus Research Center, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Bipin Vaidya
- Department of Food Science and Technology and Foodborne Virus Research Center, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Se-Young Cho
- Department of Food Science and Technology and Foodborne Virus Research Center, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Joseph Kwon
- Department of BioChemical Analysis, Korea Basic Science Institute, Daejeon 34133, Republic of Korea
| | - Duwoon Kim
- Department of Food Science and Technology and Foodborne Virus Research Center, Chonnam National University, Gwangju 61186, Republic of Korea
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Abstract
Retroviruses are widely distributed in all vertebrates, as are their endogenous forms, endogenous retroviruses (ERV), which serve as "fossil" evidence to trace the ancient origins and history of virus-host interactions over millions of years. The retroviral envelope (Env) plays a significant role in host range determination, but major information on their genetic diversification and evolution in anamniotes is lacking. Here, by incorporating multiple-round in silico similarity search and phylogenomic analysis, more than 30,000 copies of ERV lineages with gamma-type Env (GTE), covalently associated Env, were discovered by searching against all fish and amphibian genomes and transcriptomic assemblies, but no beta-type Env (BTE), noncovalently associated Env, was found. Furthermore, a nine-type classification system of anamniote GTE was proposed by combining phylogenetic and domain/motif analyses. The elastic genomic organization and overall phylogenetic incongruence between anamniotic Env and its neighboring polymerase (Pol) implied that early retroviral diversification in anamniotic vertebrates was facilitated by frequent recombination. At last, host cellular opioid growth factor receptor (OGFr) gene capturing by anamniotic ERVs with GTE was reported for the first time. Overall, our findings overturn traditional Pol genotyping and reveal a complex evolutionary history of anamniotic retroviruses inferred by Env evolution. IMPORTANCE Although the retroviral envelope (Env) protein in amniotes has been well studied, its evolutionary history in anamniotic vertebrates is ambiguous. By analyzing more than 30,000 copies of ERV lineages with gamma-type Env (GTE) in anamniotes, several important evolutionary features were identified. First, GTE was found to be widely distributed among different amphibians and fish. Second, nine types of GTE were discovered and defined, revealing their great genetic diversity. Third, the incongruence between the Env and Pol phylogenies suggested that frequent recombination shaped the early evolution of anamniote retroviruses. Fourth, an ancient horizontal gene transfer event was discovered from anamniotes to ERVs with GTE. These findings reveal a complex evolution pattern for retroviral Env in anamniotes.
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Rutherford HA, Clarke A, Chambers EV, Petts JJ, Carson EG, Isles HM, Duque-Jaramillo A, Renshaw SA, Levraud JP, Hamilton N. A zebrafish reporter line reveals immune and neuronal expression of endogenous retrovirus. Dis Model Mech 2022; 15:dmm048921. [PMID: 35142349 PMCID: PMC9016899 DOI: 10.1242/dmm.048921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 02/01/2022] [Indexed: 01/12/2023] Open
Abstract
Endogenous retroviruses (ERVs) are fossils left in our genome from retrovirus infections of the past. Their sequences are part of every vertebrate genome and their random integrations are thought to have contributed to evolution. Although ERVs are mainly silenced by the host genome, they have been found to be activated in multiple disease states, such as auto-inflammatory disorders and neurological diseases. However, the numerous copies in mammalian genomes and the lack of tools to study them make defining their role in health and diseases challenging. In this study, we identified eight copies of the zebrafish endogenous retrovirus zferv. We created and characterised the first in vivo ERV reporter line in any species. Using a combination of live imaging, flow cytometry and single-cell RNA sequencing, we mapped zferv expression to early T cells and neurons. Thus, this new tool identified tissues expressing ERV in zebrafish, highlighting a potential role of ERV during brain development and strengthening the hypothesis that ERV play a role in immunity and neurological diseases. This transgenic line is therefore a suitable tool to study the function of ERV in health and diseases.
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Affiliation(s)
- Holly A. Rutherford
- The Bateson Centre, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield S10 2TN, UK
| | - Amy Clarke
- The Bateson Centre, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield S10 2TN, UK
| | - Emily V. Chambers
- The Bioinformatics Core, Faculty of Medicine and Dentistry, University of Sheffield, Sheffield S10 2TN, UK
| | - Jessica J. Petts
- The Bateson Centre, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield S10 2TN, UK
| | - Euan G. Carson
- The Bateson Centre, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield S10 2TN, UK
| | - Hannah M. Isles
- The Bateson Centre, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield S10 2TN, UK
| | - Alejandra Duque-Jaramillo
- Institute of Microbiology (IMUL), Lausanne University Hospital and University of Lausanne, Rue du Bugnon 48, 1011 Lausanne, Switzerland
| | - Stephen A. Renshaw
- The Bateson Centre, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield S10 2TN, UK
| | - Jean-Pierre Levraud
- Macrophages et Développement de l'Immunité, Institut Pasteur, CNRS UMR3738, 25 Rue du Docteur Roux, 75015 Paris,France
| | - Noémie Hamilton
- The Bateson Centre, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield S10 2TN, UK
- The Institute of Neuroscience, University of Sheffield, Sheffield S10 2TN, UK
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Li W, Li X, Ma X, Xiao W, Zhang J. Mapping the m1A, m5C, m6A and m7G methylation atlas in zebrafish brain under hypoxic conditions by MeRIP-seq. BMC Genomics 2022; 23:105. [PMID: 35135476 PMCID: PMC8822802 DOI: 10.1186/s12864-022-08350-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 01/31/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The epigenetic modifications play important regulatory roles in tissue development, maintenance of physiological functions and pathological process. RNA methylations, including newly identified m1A, m5C, m6A and m7G, are important epigenetic modifications. However, how these modifications are distributed in the transcriptome of vertebrate brains and whether their abundance is altered under pathological conditions are still poorly understood. In this study, we chose the model animal of zebrafish to conduct a systematic study to investigate the mRNA methylation atlas in the brain. RESULTS By performing unbiased analyses of the m1A, m5C, m6A and m7G methylation of mRNA, we found that within the whole brain transcriptome, with the increase of the gene expression levels, the overall level of each of these four modifications on the related genes was also progressively increased. Further bioinformatics analysis indicated that the zebrafish brain has an abundance of m1A modifications. In the hypoxia-treated zebrafish brains, the proportion of m1A is decreased, affecting the RNA splicing and zebrafish endogenous retroviruses. CONCLUSIONS Our study presents the first comprehensive atlas of m1A, m5C, m6A and m7G in the epitranscriptome of the zebrafish brain and reveals the distribution of these modifications in mRNA under hypoxic conditions. These data provide an invaluable resource for further research on the involvement of m1A, m5C, m6A and m7G in the regulation of miRNA and repeat elements in vertebrates, and provide new thoughts to study the brain hypoxic injury on the aspect of epitranscriptome.
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Affiliation(s)
- Wei Li
- Affiliated Hospital of Guangdong Medical University & Key Laboratory of Zebrafish Model for Development and Disease of Guangdong Medical University, Zhanjiang, 524001, China
| | - Xiaoyu Li
- Affiliated Hospital of Guangdong Medical University & Key Laboratory of Zebrafish Model for Development and Disease of Guangdong Medical University, Zhanjiang, 524001, China
| | - Xunjie Ma
- Affiliated Hospital of Guangdong Medical University & Key Laboratory of Zebrafish Model for Development and Disease of Guangdong Medical University, Zhanjiang, 524001, China
| | - Wei Xiao
- Affiliated Hospital of Guangdong Medical University & Key Laboratory of Zebrafish Model for Development and Disease of Guangdong Medical University, Zhanjiang, 524001, China
| | - Jingjing Zhang
- Affiliated Hospital of Guangdong Medical University & Key Laboratory of Zebrafish Model for Development and Disease of Guangdong Medical University, Zhanjiang, 524001, China.
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Genome-Wide Characterization of Zebrafish Endogenous Retroviruses Reveals Unexpected Diversity in Genetic Organizations and Functional Potentials. Microbiol Spectr 2021; 9:e0225421. [PMID: 34908463 PMCID: PMC8672886 DOI: 10.1128/spectrum.02254-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Endogenous retroviruses (ERVs) occupy a substantial fraction of mammalian genomes. However, whether ERVs extensively exist in ancient vertebrates remains unexplored. Here, we performed a genome-wide characterization of ERVs in a zebrafish (Danio rerio) model. Approximately 3,315 ERV-like elements (DrERVs) were identified as Gypsy, Copia, Bel, and class I−III groups. DrERVs accounted for approximately 2.3% of zebrafish genome and were distributed in all 25 chromosomes, with a remarkable bias on chromosome 4. Gypsy and class I are the two most abundant groups with earlier insertion times. The vast majority of the DrERVs have varied structural defects. A total of 509 gag and 71 env genes with coding potentials were detected. The env-coding elements were well-characterized and classified into four subgroups. A ERV-E4.8.43-DanRer element shows high similarity with HERV9NC-int in humans and analogous sequences were detected in species spanning from fish to mammals. RNA-seq data showed that hundreds of DrERVs were expressed in embryos and tissues under physiological conditions, and most of them exhibited stage and tissue specificity. Additionally, 421 DrERVs showed strong responsiveness to virus infection. A unique group of DrERVs with immune-relevant genes, such as fga, ddx41, ftr35, igl1c3, and tbk1, instead of intrinsic viral genes were identified. These DrERVs are regulated by transcriptional factors binding at the long terminal repeats. This study provided a survey of the composition, phylogeny, and potential functions of ERVs in a fish model, which benefits the understanding of the evolutionary history of ERVs from fish to mammals. IMPORTANCE Endogenous retroviruses (ERVs) are relics of past infection that constitute up to 8% of the human genome. Understanding the genetic evolution of the ERV family and the interplay of ERVs and encoded RNAs and proteins with host function has become a new frontier in biology. Fish, as the most primitive vertebrate host for retroviruses, is an indispensable integral part for such investigations. In the present study, we report the genome-wide characterization of ERVs in zebrafish, an attractive model organism of ancient vertebrates from multiple perspectives, including composition, genomic organization, chromosome distribution, classification, phylogeny, insertion time, characterization of gag and env genes, and expression profiles in embryos and tissues. The result helps uncover the evolutionarily conserved and fish-specific ERVs, as well as the immune-relevant ERVs in response to virus infection. This study demonstrates the previously unrecognized abundance, diversification, and extensive activity of ERVs at the early stage of ERV evolution.
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Yedavalli VRK, Patil A, Parrish J, Kozak CA. A novel class III endogenous retrovirus with a class I envelope gene in African frogs with an intact genome and developmentally regulated transcripts in Xenopus tropicalis. Retrovirology 2021; 18:20. [PMID: 34261506 PMCID: PMC8278194 DOI: 10.1186/s12977-021-00564-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 06/29/2021] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Retroviruses exist as exogenous infectious agents and as endogenous retroviruses (ERVs) integrated into host chromosomes. Such endogenous retroviruses (ERVs) are grouped into three classes roughly corresponding to the seven genera of infectious retroviruses: class I (gamma-, epsilonretroviruses), class II (alpha-, beta-, delta-, lentiretroviruses) and class III (spumaretroviruses). Some ERVs have counterparts among the known infectious retroviruses, while others represent paleovirological relics of extinct or undiscovered retroviruses. RESULTS Here we identify an intact ERV in the Anuran amphibian, Xenopus tropicalis. XtERV-S has open reading frames (ORFs) for gag, pol (polymerase) and env (envelope) genes, with a small additional ORF in pol and a serine tRNA primer binding site. It has unusual features and domain relationships to known retroviruses. Analyses based on phylogeny and functional motifs establish that XtERV-S gag and pol genes are related to the ancient env-less class III ERV-L family but the surface subunit of env is unrelated to known retroviruses while its transmembrane subunit is class I-like. LTR constructs show transcriptional activity, and XtERV-S transcripts are detected in embryos after the maternal to zygotic mid-blastula transition and before the late tailbud stage. Tagged Gag protein shows typical subcellular localization. The presence of ORFs in all three protein-coding regions along with identical 5' and 3' LTRs (long terminal repeats) indicate this is a very recent germline acquisition. There are older, full-length, nonorthologous, defective copies in Xenopus laevis and the distantly related African bullfrog, Pyxicephalus adspersus. Additional older, internally deleted copies in X. tropicalis carry a 300 bp LTR substitution. CONCLUSIONS XtERV-S represents a genera-spanning member of the largely env-less class III ERV that has ancient and modern copies in Anurans. This provirus has an env ORF with a surface subunit unrelated to known retroviruses and a transmembrane subunit related to class I gammaretroviruses in sequence and organization, and is expressed in early embryogenesis. Additional XtERV-S-related but defective copies are present in X. tropicalis and other African frog taxa. XtERV-S is an unusual class III ERV variant, and it may represent an important transitional retroviral form that has been spreading in African frogs for tens of millions of years.
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Affiliation(s)
- Venkat R K Yedavalli
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, MD, 20892, USA
| | - Akash Patil
- Department of Biomedical Engineering, John Hopkins University, Baltimore, MD, 21205, USA
| | - Janay Parrish
- Internal Medicine, Northwell Health, Lenox Hill Hospital, New York, NY, 10075, USA
| | - Christine A Kozak
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, MD, 20892, USA.
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Sullivan C, Soos BL, Millard PJ, Kim CH, King BL. Modeling Virus-Induced Inflammation in Zebrafish: A Balance Between Infection Control and Excessive Inflammation. Front Immunol 2021; 12:636623. [PMID: 34025644 PMCID: PMC8138431 DOI: 10.3389/fimmu.2021.636623] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 04/21/2021] [Indexed: 12/16/2022] Open
Abstract
The inflammatory response to viral infection in humans is a dynamic process with complex cell interactions that are governed by the immune system and influenced by both host and viral factors. Due to this complexity, the relative contributions of the virus and host factors are best studied in vivo using animal models. In this review, we describe how the zebrafish (Danio rerio) has been used as a powerful model to study host-virus interactions and inflammation by combining robust forward and reverse genetic tools with in vivo imaging of transparent embryos and larvae. The innate immune system has an essential role in the initial inflammatory response to viral infection. Focused studies of the innate immune response to viral infection are possible using the zebrafish model as there is a 4-6 week timeframe during development where they have a functional innate immune system dominated by neutrophils and macrophages. During this timeframe, zebrafish lack a functional adaptive immune system, so it is possible to study the innate immune response in isolation. Sequencing of the zebrafish genome has revealed significant genetic conservation with the human genome, and multiple studies have revealed both functional conservation of genes, including those critical to host cell infection and host cell inflammatory response. In addition to studying several fish viruses, zebrafish infection models have been developed for several human viruses, including influenza A, noroviruses, chikungunya, Zika, dengue, herpes simplex virus type 1, Sindbis, and hepatitis C virus. The development of these diverse viral infection models, coupled with the inherent strengths of the zebrafish model, particularly as it relates to our understanding of macrophage and neutrophil biology, offers opportunities for far more intensive studies aimed at understanding conserved host responses to viral infection. In this context, we review aspects relating to the evolution of innate immunity, including the evolution of viral pattern recognition receptors, interferons and interferon receptors, and non-coding RNAs.
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Affiliation(s)
- Con Sullivan
- College of Arts and Sciences, University of Maine at Augusta, Bangor, ME, United States
| | - Brandy-Lee Soos
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, United States
| | - Paul J. Millard
- Department of Environmental and Sustainable Engineering, University at Albany, Albany, NY, United States
| | - Carol H. Kim
- Department of Biomedical Sciences, University at Albany, Albany, NY, United States
- Department of Biological Sciences, University at Albany, Albany, NY, United States
| | - Benjamin L. King
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, United States
- Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME, United States
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Carducci F, Barucca M, Canapa A, Carotti E, Biscotti MA. Mobile Elements in Ray-Finned Fish Genomes. Life (Basel) 2020; 10:E221. [PMID: 32992841 PMCID: PMC7599744 DOI: 10.3390/life10100221] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/18/2020] [Accepted: 09/22/2020] [Indexed: 12/12/2022] Open
Abstract
Ray-finned fishes (Actinopterygii) are a very diverse group of vertebrates, encompassing species adapted to live in freshwater and marine environments, from the deep sea to high mountain streams. Genome sequencing offers a genetic resource for investigating the molecular bases of this phenotypic diversity and these adaptations to various habitats. The wide range of genome sizes observed in fishes is due to the role of transposable elements (TEs), which are powerful drivers of species diversity. Analyses performed to date provide evidence that class II DNA transposons are the most abundant component in most fish genomes and that compared to other vertebrate genomes, many TE superfamilies are present in actinopterygians. Moreover, specific TEs have been reported in ray-finned fishes as a possible result of an intricate relationship between TE evolution and the environment. The data summarized here underline the biological interest in Actinopterygii as a model group to investigate the mechanisms responsible for the high biodiversity observed in this taxon.
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Affiliation(s)
| | | | | | | | - Maria Assunta Biscotti
- Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, 60131 Ancona, Italy; (F.C.); (M.B.); (A.C.); (E.C.)
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13
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Traldi JB, Ziemniczak K, de Fátima Martinez J, Blanco DR, Lui RL, Schemberger MO, Nogaroto V, Moreira-Filho O, Vicari MR. Chromosome Mapping of H1 and H4 Histones in Parodontidae (Actinopterygii: Characiformes): Dispersed and/or Co-Opted Transposable Elements? Cytogenet Genome Res 2019; 158:106-113. [PMID: 31203273 DOI: 10.1159/000500987] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2019] [Indexed: 01/22/2023] Open
Abstract
The karyotypes of the family Parodontidae consist of 2n = 54 chromosomes. The main chromosomal evolutionary changes of its species are attributed to chromosome rearrangements in repetitive DNA regions in their genomes. Physical mapping of the H1 and H4 histones was performed in 7 Parodontidae species to analyze the chromosome rearrangements involved in karyotype diversification in the group. In parallel, the observation of a partial sequence of an endogenous retrovirus (ERV) retrotransposon in the H1 histone sequence was evaluated to verify molecular co-option of the transposable elements (TEs) and to assess paralogous sequence dispersion in the karyotypes. Six of the studied species had an interstitial histone gene cluster in the short arm of the autosomal pair 13. Besides this interstitial cluster, in Apareiodon davisi, a probable further site was detected in the terminal region of the long arm in the same chromosome pair. The H1/H4 clusters in Parodon cf. pongoensis were located in the smallest chromosomes (pair 20). In addition, scattered H1 signals were observed on the chromosomes in all species. The H1 sequence showed an ERV in the open reading frame (ORF), and the scattered H1 signals on the chromosomes were attributed to the ERV's location. The H4 sequence had no similarity to the TEs and displayed no dispersed signals. Furthermore, the degeneration of the inner ERV in the H1 sequence (which overlapped a stretch of the H1 ORF) was discussed regarding the likelihood of molecular co-option of this retroelement in histone gene function in Parodontidae.
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14
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De novo assembly, characterization, functional annotation and expression patterns of the black tiger shrimp (Penaeus monodon) transcriptome. Sci Rep 2018; 8:13553. [PMID: 30202061 PMCID: PMC6131155 DOI: 10.1038/s41598-018-31148-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 08/12/2018] [Indexed: 12/17/2022] Open
Abstract
The black tiger shrimp (Penaeus monodon) remains the second most widely cultured shrimp species globally; however, issues with disease and domestication have seen production levels stagnate over the past two decades. To help identify innovative solutions needed to resolve bottlenecks hampering the culture of this species, it is important to generate genetic and genomic resources. Towards this aim, we have produced the most complete publicly available P. monodon transcriptome database to date based on nine adult tissues and eight early life-history stages (BUSCO - Complete: 98.2% [Duplicated: 51.3%], Fragmented: 0.8%, Missing: 1.0%). The assembly resulted in 236,388 contigs, which were then further segregated into 99,203 adult tissue specific and 58,678 early life-history stage specific clusters. While annotation rates were low (approximately 30%), as is typical for a non-model organisms, annotated transcript clusters were successfully mapped to several hundred functional KEGG pathways. Transcripts were clustered into groups within tissues and early life-history stages, providing initial evidence for their roles in specific tissue functions, or developmental transitions. We expect the transcriptome to provide an essential resource to investigate the molecular basis of commercially relevant-significant traits in P. monodon and other shrimp species.
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15
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Chernyavskaya Y, Mudbhary R, Zhang C, Tokarz D, Jacob V, Gopinath S, Sun X, Wang S, Magnani E, Madakashira BP, Yoder JA, Hoshida Y, Sadler KC. Loss of DNA methylation in zebrafish embryos activates retrotransposons to trigger antiviral signaling. Development 2017; 144:2925-2939. [PMID: 28698226 DOI: 10.1242/dev.147629] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 07/02/2017] [Indexed: 12/19/2022]
Abstract
Complex cytoplasmic nucleotide-sensing mechanisms can recognize foreign DNA based on a lack of methylation and initiate an immune response to clear the infection. Zebrafish embryos with global DNA hypomethylation caused by mutations in the ubiquitin-like with PHD and ring finger domains 1 (uhrf1) or DNA methyltransferase 1 (dnmt1) genes exhibit a robust interferon induction characteristic of the first line of defense against viral infection. We found that this interferon induction occurred in non-immune cells and examined whether intracellular viral sensing pathways in these cells were the trigger. RNA-seq analysis of uhrf1 and dnmt1 mutants revealed widespread induction of Class I retrotransposons and activation of cytoplasmic DNA viral sensors. Attenuating Sting, phosphorylated Tbk1 and, importantly, blocking reverse transcriptase activity suppressed the expression of interferon genes in uhrf1 mutants. Thus, activation of transposons in cells with global DNA hypomethylation mimics a viral infection by activating cytoplasmic DNA sensors. This suggests that antiviral pathways serve as surveillance of cells that have derepressed intragenomic parasites due to DNA hypomethylation.
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Affiliation(s)
- Yelena Chernyavskaya
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Program in Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Raksha Mudbhary
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA
| | - Chi Zhang
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Program in Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Debra Tokarz
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC 27607, USA.,Center for Comparative Medicine and Translational Research, North Carolina State University, Raleigh, NC 27607, USA
| | - Vinitha Jacob
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA
| | - Smita Gopinath
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA
| | - Xiaochen Sun
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Liver Cancer Program, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA
| | - Shuang Wang
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA
| | - Elena Magnani
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Program in Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | | | - Jeffrey A Yoder
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC 27607, USA.,Center for Comparative Medicine and Translational Research, North Carolina State University, Raleigh, NC 27607, USA
| | - Yujin Hoshida
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Program in Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.,Liver Cancer Program, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA
| | - Kirsten C Sadler
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA .,Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA.,Program in Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.,Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, Box 1020, New York, NY 10029, USA
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16
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Dill JA, Williams SM, Leary JH, Ng TFF, Camus AC. Investigation of epizootic papillomatosis in bluegill Lepomis macrochirus (Rafinesque 1810) using next-generation sequencing. JOURNAL OF FISH DISEASES 2017; 40:947-952. [PMID: 27696444 DOI: 10.1111/jfd.12556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 07/29/2016] [Accepted: 08/01/2016] [Indexed: 06/06/2023]
Affiliation(s)
- J A Dill
- Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - S M Williams
- Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
- Poultry Diagnostic and Research Center, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - J H Leary
- Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - T F F Ng
- Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
- Division of Viral Diseases, NCIRD, Centers for Disease Control, Atlanta, GA, USA
| | - A C Camus
- Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
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17
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Sotero-Caio CG, Platt RN, Suh A, Ray DA. Evolution and Diversity of Transposable Elements in Vertebrate Genomes. Genome Biol Evol 2017; 9:161-177. [PMID: 28158585 PMCID: PMC5381603 DOI: 10.1093/gbe/evw264] [Citation(s) in RCA: 159] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2016] [Indexed: 12/21/2022] Open
Abstract
Transposable elements (TEs) are selfish genetic elements that mobilize in genomes via transposition or retrotransposition and often make up large fractions of vertebrate genomes. Here, we review the current understanding of vertebrate TE diversity and evolution in the context of recent advances in genome sequencing and assembly techniques. TEs make up 4-60% of assembled vertebrate genomes, and deeply branching lineages such as ray-finned fishes and amphibians generally exhibit a higher TE diversity than the more recent radiations of birds and mammals. Furthermore, the list of taxa with exceptional TE landscapes is growing. We emphasize that the current bottleneck in genome analyses lies in the proper annotation of TEs and provide examples where superficial analyses led to misleading conclusions about genome evolution. Finally, recent advances in long-read sequencing will soon permit access to TE-rich genomic regions that previously resisted assembly including the gigantic, TE-rich genomes of salamanders and lungfishes.
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Affiliation(s)
| | - Roy N. Platt
- Department of Biological Sciences, Texas Tech University, Lubbock, TX
| | - Alexander Suh
- Department of Evolutionary Biology (EBC), Uppsala University, Uppsala, Sweden
| | - David A. Ray
- Department of Biological Sciences, Texas Tech University, Lubbock, TX
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18
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Naville M, Volff JN. Endogenous Retroviruses in Fish Genomes: From Relics of Past Infections to Evolutionary Innovations? Front Microbiol 2016; 7:1197. [PMID: 27555838 PMCID: PMC4977317 DOI: 10.3389/fmicb.2016.01197] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 07/19/2016] [Indexed: 12/16/2022] Open
Abstract
The increasing availability of fish genome sequences has allowed to gain new insights into the diversity and host distribution of retroviruses in fish and other vertebrates. This distribution can be assessed through the identification and analysis of endogenous retroviruses, which are proviral remnants of past infections integrated in genomes. Retroviral sequences are probably important for evolution through their ability to induce rearrangements and to contribute regulatory and coding sequences; they may also protect their host against new infections. We argue that the current mass of genome sequences will soon strongly improve our understanding of retrovirus diversity and evolution in aquatic animals, with the identification of new/re-emerging elements and host resistance genes that restrict their infectivity.
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Affiliation(s)
- Magali Naville
- Génomique Évolutive des Poissons, Institut de Génomique Fonctionnelle de Lyon, École Normale Supérieure de Lyon, CNRS, Université Lyon 1 Lyon, France
| | - Jean-Nicolas Volff
- Génomique Évolutive des Poissons, Institut de Génomique Fonctionnelle de Lyon, École Normale Supérieure de Lyon, CNRS, Université Lyon 1 Lyon, France
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19
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Collymore C, Crim MJ, Lieggi C. Recommendations for Health Monitoring and Reporting for Zebrafish Research Facilities. Zebrafish 2016; 13 Suppl 1:S138-48. [PMID: 26991393 PMCID: PMC4932782 DOI: 10.1089/zeb.2015.1210] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The presence of subclinical infection or clinical disease in laboratory zebrafish may have a significant impact on research results, animal health and welfare, and transfer of animals between institutions. As use of zebrafish as a model of disease increases, a harmonized method for monitoring and reporting the health status of animals will facilitate the transfer of animals, allow institutions to exclude diseases that may negatively impact their research programs, and improve animal health and welfare. All zebrafish facilities should implement a health monitoring program. In this study, we review important aspects of a health monitoring program, including choice of agents, samples for testing, available testing methodologies, housing and husbandry, cost, test subjects, and a harmonized method for reporting results. Facilities may use these recommendations to implement their own health monitoring program.
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Affiliation(s)
- Chereen Collymore
- Division of Comparative Medicine, University of Toronto, Toronto, Ontario, Canada
| | | | - Christine Lieggi
- Center for Comparative Medicine and Pathology, Weill Cornell Medical College and Memorial Sloan Kettering Cancer Center, New York, New York
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20
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Nam GH, Gim JA, Lee HE, Kim WJ, Jung H, Kim W, Kim HS. Expression and promoter activity of endogenous retroviruses in the Olive flounder (Paralichthys olivaceus). Genes Genomics 2016. [DOI: 10.1007/s13258-016-0404-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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21
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Correa AMS, Ainsworth TD, Rosales SM, Thurber AR, Butler CR, Vega Thurber RL. Viral Outbreak in Corals Associated with an In Situ Bleaching Event: Atypical Herpes-Like Viruses and a New Megavirus Infecting Symbiodinium. Front Microbiol 2016; 7:127. [PMID: 26941712 PMCID: PMC4761846 DOI: 10.3389/fmicb.2016.00127] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 01/25/2016] [Indexed: 12/03/2022] Open
Abstract
Previous studies of coral viruses have employed either microscopy or metagenomics, but few have attempted to comprehensively link the presence of a virus-like particle (VLP) to a genomic sequence. We conducted transmission electron microscopy imaging and virome analysis in tandem to characterize the most conspicuous viral types found within the dominant Pacific reef-building coral genus Acropora. Collections for this study inadvertently captured what we interpret as a natural outbreak of viral infection driven by aerial exposure of the reef flat coincident with heavy rainfall and concomitant mass bleaching. All experimental corals in this study had high titers of viral particles. Three of the dominant VLPs identified were observed in all tissue layers and budding out from the epidermis, including viruses that were ∼70, ∼120, and ∼150 nm in diameter; these VLPs all contained electron dense cores. These morphological traits are reminiscent of retroviruses, herpesviruses, and nucleocytoplasmic large DNA viruses (NCLDVs), respectively. Some 300–500 nm megavirus-like VLPs also were observed within and associated with dinoflagellate algal endosymbiont (Symbiodinium) cells. Abundant sequence similarities to a gammaretrovirus, herpesviruses, and members of the NCLDVs, based on a virome generated from five Acropora aspera colonies, corroborated these morphology-based identifications. Additionally sequence similarities to two diagnostic genes, a MutS and (based on re-annotation of sequences from another study) a DNA polymerase B gene, most closely resembled Pyramimonas orientalis virus, demonstrating the association of a cosmopolitan megavirus with Symbiodinium. We also identified several other virus-like particles in host tissues, along with sequences phylogenetically similar to circoviruses, phages, and filamentous viruses. This study suggests that viral outbreaks may be a common but previously undocumented component of natural bleaching events, particularly following repeated episodes of multiple environmental stressors.
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Affiliation(s)
- Adrienne M S Correa
- Department of Microbiology, Oregon State UniversityCorvallis, OR, USA; BioSciences at Rice, Rice UniversityHouston, TX, USA
| | - Tracy D Ainsworth
- ARC Centre of Excellence for Coral Reef Studies, James Cook University Townsville, QLD, Australia
| | | | - Andrew R Thurber
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University Corvallis, OR, USA
| | - Christopher R Butler
- Department of Microbiology, Oregon State UniversityCorvallis, OR, USA; Department of Viticulture and Enology, University of California at DavisDavis, CA, USA
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22
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Mourier T, Mollerup S, Vinner L, Hansen TA, Kjartansdóttir KR, Guldberg Frøslev T, Snogdal Boutrup T, Nielsen LP, Willerslev E, Hansen AJ. Characterizing novel endogenous retroviruses from genetic variation inferred from short sequence reads. Sci Rep 2015; 5:15644. [PMID: 26493184 PMCID: PMC4616055 DOI: 10.1038/srep15644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 09/21/2015] [Indexed: 02/06/2023] Open
Abstract
From Illumina sequencing of DNA from brain and liver tissue from the lion, Panthera leo, and tumor samples from the pike-perch, Sander lucioperca, we obtained two assembled sequence contigs with similarity to known retroviruses. Phylogenetic analyses suggest that the pike-perch retrovirus belongs to the epsilonretroviruses, and the lion retrovirus to the gammaretroviruses. To determine if these novel retroviral sequences originate from an endogenous retrovirus or from a recently integrated exogenous retrovirus, we assessed the genetic diversity of the parental sequences from which the short Illumina reads are derived. First, we showed by simulations that we can robustly infer the level of genetic diversity from short sequence reads. Second, we find that the measures of nucleotide diversity inferred from our retroviral sequences significantly exceed the level observed from Human Immunodeficiency Virus infections, prompting us to conclude that the novel retroviruses are both of endogenous origin. Through further simulations, we rule out the possibility that the observed elevated levels of nucleotide diversity are the result of co-infection with two closely related exogenous retroviruses.
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Affiliation(s)
- Tobias Mourier
- Centre for GeoGenetics, Museum of Natural History of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - Sarah Mollerup
- Centre for GeoGenetics, Museum of Natural History of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - Lasse Vinner
- Centre for GeoGenetics, Museum of Natural History of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Arn Hansen
- Centre for GeoGenetics, Museum of Natural History of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - Kristín Rós Kjartansdóttir
- Centre for GeoGenetics, Museum of Natural History of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - Tobias Guldberg Frøslev
- Centre for GeoGenetics, Museum of Natural History of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - Torsten Snogdal Boutrup
- Section for Virology, National Veterinary Institute, Technical University of Denmark, Frederiksberg, Denmark
| | - Lars Peter Nielsen
- Department for Autoimmunology and Biomarkers, Statens Serum Institut, Copenhagen, Denmark
| | - Eske Willerslev
- Centre for GeoGenetics, Museum of Natural History of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - Anders J Hansen
- Centre for GeoGenetics, Museum of Natural History of Denmark, University of Copenhagen, Copenhagen, Denmark
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23
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Shi J, Zhang H, Gong R, Xiao G. Characterization of the fusion core in zebrafish endogenous retroviral envelope protein. Biochem Biophys Res Commun 2015; 460:633-8. [PMID: 25804638 PMCID: PMC7092836 DOI: 10.1016/j.bbrc.2015.03.081] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 03/14/2015] [Indexed: 10/26/2022]
Abstract
Zebrafish endogenous retrovirus (ZFERV) is the unique endogenous retrovirus in zebrafish, as yet, containing intact open reading frames of its envelope protein gene in zebrafish genome. Similarly, several envelope proteins of endogenous retroviruses in human and other mammalian animal genomes (such as syncytin-1 and 2 in human, syncytin-A and B in mouse) were identified and shown to be functional in induction of cell-cell fusion involved in placental development. ZFERV envelope protein (Env) gene appears to be also functional in vivo because it is expressible. After sequence alignment, we found ZFERV Env shares similar structural profiles with syncytin and other type I viral envelopes, especially in the regions of N- and C-terminal heptad repeats (NHR and CHR) which were crucial for membrane fusion. We expressed the regions of N + C protein in the ZFERV Env (residues 459-567, including predicted NHR and CHR) to characterize the fusion core structure. We found N + C protein could form a stable coiled-coil trimer that consists of three helical NHR regions forming a central trimeric core, and three helical CHR regions packing into the grooves on the surface of the central core. The structural characterization of the fusion core revealed the possible mechanism of fusion mediated by ZFERV Env. These results gave comprehensive explanation of how the ancient virus infects the zebrafish and integrates into the genome million years ago, and showed a rational clue for discovery of physiological significance (e.g., medicate cell-cell fusion).
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Affiliation(s)
- Jian Shi
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, China; State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Huaidong Zhang
- CAS Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Rui Gong
- CAS Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China.
| | - Gengfu Xiao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, China; State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China.
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24
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Henriet S, Sumic S, Doufoundou-Guilengui C, Jensen MF, Grandmougin C, Fal K, Thompson E, Volff JN, Chourrout D. Embryonic expression of endogenous retroviral RNAs in somatic tissues adjacent to the Oikopleura germline. Nucleic Acids Res 2015; 43:3701-11. [PMID: 25779047 PMCID: PMC4402516 DOI: 10.1093/nar/gkv169] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 02/20/2015] [Indexed: 11/19/2022] Open
Abstract
Selective pressure to maintain small genome size implies control of transposable elements, and most old classes of retrotransposons are indeed absent from the very compact genome of the tunicate Oikopleura dioica. Nonetheless, two families of retrotransposons are present, including the Tor elements. The gene organization within Tor elements is similar to that of LTR retrotransposons and retroviruses. In addition to gag and pol, many Tor elements carry a third gene encoding viral envelope-like proteins (Env) that may mediate infection. We show that the Tor family contains distinct classes of elements. In some classes, env mRNA is transcribed from the 5′LTR as in retroviruses. In others, env is transcribed from an additional promoter located downstream of the 5′LTR. Tor Env proteins are membrane-associated glycoproteins which exhibit some features of viral membrane fusion proteins. Whereas some elements are expressed in the adult testis, many others are specifically expressed in embryonic somatic cells adjacent to primordial germ cells. Such embryonic expression depends on determinants present in the Tor elements and not on their surrounding genomic environment. Our study shows that unusual modes of transcription and expression close to the germline may contribute to the proliferation of Tor elements.
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Affiliation(s)
- Simon Henriet
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway
| | - Sara Sumic
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway
| | | | - Marit Flo Jensen
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway
| | - Camille Grandmougin
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway
| | - Kateryna Fal
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway
| | - Eric Thompson
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway Department of Biology, University of Bergen, Bergen, N-5020, Norway
| | - Jean-Nicolas Volff
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon - CNRS UMR 5242 - INRA USC 1370, Lyon, 69364 Lyon cedex 07, France
| | - Daniel Chourrout
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway
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25
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Multiple groups of endogenous epsilon-like retroviruses conserved across primates. J Virol 2014; 88:12464-71. [PMID: 25142585 DOI: 10.1128/jvi.00966-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Several types of cancer in fish are caused by retroviruses, including those responsible for major outbreaks of disease, such as walleye dermal sarcoma virus and salmon swim bladder sarcoma virus. These viruses form a phylogenetic group often described as the epsilonretrovirus genus. Epsilon-like retroviruses have become endogenous retroviruses (ERVs) on several occasions, integrating into germ line cells to become part of the host genome, and sections of fish and amphibian genomes are derived from epsilon-like retroviruses. However, epsilon-like ERVs have been identified in very few mammals. We have developed a pipeline to screen full genomes for ERVs, and using this pipeline, we have located over 800 endogenous epsilon-like ERV fragments in primate genomes. Genomes from 32 species of mammals and birds were screened, and epsilon-like ERV fragments were found in all primate and tree shrew genomes but no others. These viruses appear to have entered the genome of a common ancestor of Old and New World monkeys between 42 million and 65 million years ago. Based on these results, there is an ancient evolutionary relationship between epsilon-like retroviruses and primates. Clearly, these viruses had the potential to infect the ancestors of primates and were at some point a common pathogen in these hosts. Therefore, this result raises questions about the potential of epsilonretroviruses to infect humans and other primates and about the evolutionary history of these retroviruses. IMPORTANCE Epsilonretroviruses are a group of retroviruses that cause several important diseases in fish. Retroviruses have the ability to become a permanent part of the DNA of their host by entering the germ line as endogenous retroviruses (ERVs), where they lose their infectivity over time but can be recognized as retroviruses for millions of years. Very few mammals are known to have epsilon-like ERVs; however, we have identified over 800 fragments of endogenous epsilon-like ERVs in the genomes of all major groups of primates, including humans. These viruses seem to have circulated and infected primate ancestors 42 to 65 million years ago. We are now interested in how these viruses have evolved and whether they have the potential to infect modern humans or other primates.
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Grau JH, Poustka AJ, Meixner M, Plötner J. LTR retroelements are intrinsic components of transcriptional networks in frogs. BMC Genomics 2014; 15:626. [PMID: 25056159 PMCID: PMC4131045 DOI: 10.1186/1471-2164-15-626] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 07/15/2014] [Indexed: 12/16/2022] Open
Abstract
Background LTR retroelements (LTR REs) constitute a major group of transposable elements widely distributed in eukaryotic genomes. Through their own mechanism of retrotranscription LTR REs enrich the genomic landscape by providing genetic variability, thus contributing to genome structure and organization. Nonetheless, transcriptomic activity of LTR REs still remains an obscure domain within cell, developmental, and organism biology. Results Here we present a first comparative analysis of LTR REs for anuran amphibians based on a full depth coverage transcriptome of the European pool frog, Pelophylax lessonae, the genome of the African clawed frog, Silurana tropicalis (release v7.1), and additional transcriptomes of S. tropicalis and Cyclorana alboguttata. We identified over 1000 copies of LTR REs from all four families (Bel/Pao, Ty1/Copia, Ty3/Gypsy, Retroviridae) in the genome of S. tropicalis and discovered transcripts of several of these elements in all RNA-seq datasets analyzed. Elements of the Ty3/Gypsy family were most active, especially Amn-san elements, which accounted for approximately 0.27% of the genome in Silurana. Some elements exhibited tissue specific expression patterns, for example Hydra1.1 and MuERV-like elements in Pelophylax. In S. tropicalis considerable transcription of LTR REs was observed during embryogenesis as soon as the embryonic genome became activated, i.e. at midblastula transition. In the course of embryonic development the spectrum of transcribed LTR REs changed; during gastrulation and neurulation MuERV-like and SnRV like retroviruses were abundantly transcribed while during organogenesis transcripts of the XEN1 retroviruses became much more active. Conclusions The differential expression of LTR REs during embryogenesis in concert with their tissue-specificity and the protein domains they encode are evidence for the functional roles these elements play as integrative parts of complex regulatory networks. Our results support the meanwhile widely accepted concept that retroelements are not simple “junk DNA” or “harmful genomic parasites” but essential components of the transcriptomic machinery in vertebrates. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-626) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- José Horacio Grau
- Dahlem Center for Genome Research and Medical Systems Biology, Fabeckstraße 60-62, 14195 Berlin, Germany.
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Levraud JP, Palha N, Langevin C, Boudinot P. Through the looking glass: witnessing host-virus interplay in zebrafish. Trends Microbiol 2014; 22:490-7. [PMID: 24865811 DOI: 10.1016/j.tim.2014.04.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 04/27/2014] [Accepted: 04/30/2014] [Indexed: 12/21/2022]
Abstract
Host-pathogen interactions can be very complex at all scales; understanding organ- or organism-level events require in vivo approaches. Besides traditional host models such as mice, the zebrafish offers an attractive cocktail of optical accessibility and genetic tractability, blended with a vertebrate-type immunity, where innate responses can easily be separated from adaptive ones. Applied to viral infections, this model has revealed unexpected idiosyncrasies among organs, which we believe may apply to the human situation. We also argue that the dynamic analysis of virus spread and immune response in zebrafish make this model particularly well suited to the exploration of the concept of infection tolerance and resistance in relation to viral diseases.
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Affiliation(s)
- Jean-Pierre Levraud
- Institut Pasteur, Macrophages et Développement de l'Immunité, Paris, France; Centre National de la Recherche Scientifique (CNRS), URA 2578, Paris, France.
| | - Nuno Palha
- Institut Pasteur, Macrophages et Développement de l'Immunité, Paris, France; Centre National de la Recherche Scientifique (CNRS), URA 2578, Paris, France
| | - Christelle Langevin
- Institut National de la Recherche Agronomique (INRA), Virologie et Immunologie Moléculaire, Jouy-en-Josas, France
| | - Pierre Boudinot
- Institut National de la Recherche Agronomique (INRA), Virologie et Immunologie Moléculaire, Jouy-en-Josas, France
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28
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Abstract
Naturally occurring viral infections have the potential to introduce confounding variability that leads to invalid and misinterpreted data. Whereas the viral diseases of research rodents are well characterized and closely monitored, no naturally occurring viral infections have been characterized for the laboratory zebrafish (Danio rerio), an increasingly important biomedical research model. Despite the ignorance about naturally occurring zebrafish viruses, zebrafish models are rapidly expanding in areas of biomedical research where the confounding effects of unknown infectious agents present a serious concern. In addition, many zebrafish research colonies remain linked to the ornamental (pet) zebrafish trade, which can contribute to the introduction of new pathogens into research colonies, whereas mice used for research are purpose bred, with no introduction of new mice from the pet industry. Identification, characterization, and monitoring of naturally occurring viruses in zebrafish are crucial to the improvement of zebrafish health, the reduction of unwanted variability, and the continued development of the zebrafish as a model organism. This article addresses the importance of identifying and characterizing the viral diseases of zebrafish as the scope of zebrafish models expands into new research areas and also briefly addresses zebrafish susceptibility to experimental viral infection and the utility of the zebrafish as an infection and immunology model.
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Affiliation(s)
- Marcus J Crim
- Comparative Medicine Program, University of Missouri, Columbia, MO 65201, USA.
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Paquette CE, Kent ML, Buchner C, Tanguay RL, Guillemin K, Mason TJ, Peterson TS. A retrospective study of the prevalence and classification of intestinal neoplasia in zebrafish (Danio rerio). Zebrafish 2013; 10:228-36. [PMID: 23544991 DOI: 10.1089/zeb.2012.0828] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
For over a decade, spontaneous intestinal neoplasia has been observed in zebrafish (Danio rerio) submitted to the ZIRC (Zebrafish International Resource Center) diagnostic service. In addition, zebrafish displayed preneoplastic intestinal changes including hyperplasia, dysplasia, and enteritis. A total of 195 zebrafish, representing 2% of the total fish submitted to the service, were diagnosed with these lesions. Neoplastic changes were classified either as adenocarcinoma or small cell carcinoma, with a few exceptions (carcinoma not otherwise specified, tubular adenoma, and tubulovillous adenoma). Tumor prevalence appeared similarly distributed between sexes and generally occurred in zebrafish greater than 1 year of age, although neoplastic changes were observed in fish 6 months of age. Eleven lines displayed these preneoplastic and neoplastic changes, including wild-types and mutants. Affected zebrafish originated from 18 facilities, but the majority of fish were from a single zebrafish research facility (hereafter referred to as the primary facility) that has submitted numerous samples to the ZIRC diagnostic service. Zebrafish from the primary facility submitted as normal sentinel fish demonstrate that these lesions are most often subclinical. Fish fed the diet from the primary facility and held at another location did not develop intestinal lesions, indicating that diet is not the etiologic agent.
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Affiliation(s)
- Colleen E Paquette
- Department of Microbiology, Oregon State University, Corvallis, OR 97331-3804, USA
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30
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Martinez-Lopez A, Chinchilla B, Encinas P, Gomez-Casado E, Estepa A, Coll JM. Replacement of the human cytomegalovirus promoter with fish enhancer and core elements to control the expression of the G gene of viral haemorrhagic septicemia virus (VHSV). J Biotechnol 2012; 164:171-8. [PMID: 22954890 DOI: 10.1016/j.jbiotec.2012.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 08/17/2012] [Accepted: 08/21/2012] [Indexed: 11/16/2022]
Abstract
This work explores some of the possibilities to replace human cytomegalovirus (CMV) core and/or enhancer promoter control elements to create new expression vectors for use with fish. The work is relevant to fish vaccination, since DNA vaccines use eukaryotic expression plasmids controlled by the human cytomegalovirus (CMV) promoter to be effective against novirhabdoviruses, such as viral haemorrhagic septicemia virus (VHSV), one of the most devastating fish viral European diseases. To reduce possible homologous recombination with fish genome, core and enhancer sequences from fish origin, such as trout interferon-inducible myxovirus protein (Mx), zebrafish retrovirus long terminal repeat (LTR) and carp β-actin (AE6), were combined with those of CMV to design alternative hybrid promoters. The substitution of CMV core and/or enhancer with the corresponding elements of Mx or the LTR core maintained a similar in vitro protein G expression level than that obtained by using the CMV promoter. Vectors using the dsRNA-inducible Mx enhancer followed either by the LTR or the AE6 cores showed the highest in vitro protein G expression levels. Furthermore, synthetic constructs using the Mx enhancer maintained their polyI:C induction capabilities despite the core used. Some of these hybrid promoters might contribute to the development of all-fish-vectors for DNA vaccines while others might be useful for more basic studies.
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31
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Genomic amplification of an endogenous retrovirus in zebrafish T-cell malignancies. Adv Hematol 2012; 2012:627920. [PMID: 22745640 PMCID: PMC3382231 DOI: 10.1155/2012/627920] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 04/17/2012] [Indexed: 02/02/2023] Open
Abstract
Genomic instability plays a crucial role in oncogenesis. Somatically acquired mutations can disable some genes and inappropriately activate others. In addition, chromosomal rearrangements can amplify, delete, or even fuse genes, altering their functions and contributing to malignant phenotypes. Using array comparative genomic hybridization (aCGH), a technique to detect numeric variations between different DNA samples, we examined genomes from zebrafish (Danio rerio) T-cell leukemias of three cancer-prone lines. In all malignancies tested, we identified recurring amplifications of a zebrafish endogenous retrovirus. This retrovirus, ZFERV, was first identified due to high expression of proviral transcripts in thymic tissue from larval and adult fish. We confirmed ZFERV amplifications by quantitative PCR analyses of DNA from wild-type fish tissue and normal and malignant D. rerio T cells. We also quantified ZFERV RNA expression and found that normal and neoplastic T cells both produce retrovirally encoded transcripts, but most cancers show dramatically increased transcription. In aggregate, these data imply that ZFERV amplification and transcription may be related to T-cell leukemogenesis. Based on these data and ZFERV's phylogenetic relation to viruses of the murine-leukemia-related virus class of gammaretroviridae, we posit that ZFERV may be oncogenic via an insertional mutagenesis mechanism.
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32
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Goldstone HMH, Tokunaga S, Schlezinger JJ, Goldstone JV, Stegeman JJ. EZR1: a novel family of highly expressed retroelements induced by TCDD and regulated by a NF-κB-like factor in embryos of zebrafish (Danio rerio). Zebrafish 2012; 9:15-25. [PMID: 22356696 DOI: 10.1089/zeb.2011.0722] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Transcript profiling using a zebrafish heart cDNA library previously revealed abundant expressed sequence tags (ESTs) upregulated in zebrafish embryos treated with the aryl hydrocarbon receptor (AHR) agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Here, we identify those ESTs as LTR-containing retroelements termed EZR1 (Expressed-Zebrafish-Retroelement group 1). EZR1 is highly redundant in the genome and includes canonical long terminal repeats (LTRs) flanking an integrase-like open reading frame and a region similar to retroviral envelope protein genes. EZR1 sequences lack reverse transcriptase, RNase H, or protease, indicating retrotransposition would be nonautonomous. No AHR binding motifs were found in the EZR1 promoter region. A putative NF-κB-binding site was found, and TCDD-treated zebrafish embryos had significantly increased levels of nuclear protein(s) binding to this sequence. Protein-EZR1 DNA complex formation was partially competed by a mammalian consensus κB sequence, consistent with NF-κB-like activation contributing to increased protein binding to this site. Mobility of the TCDD-induced protein-EZR1 complex differed from that of authentic NF-κB protein bound to the consensus κB site. The results suggest that EZR1 is regulated by interaction with NF-κB or NF-κB-like protein(s) different from the NF-κB protein binding to the consensus κB site. The nature of the NF-κB-like protein and the relationship between EZR1 induction and cardiovascular toxicity caused by TCDD warrant further investigation.
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Affiliation(s)
- Heather M H Goldstone
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
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33
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Characterization of a Xenopus tropicalis endogenous retrovirus with developmental and stress-dependent expression. J Virol 2010; 85:2167-79. [PMID: 21159866 DOI: 10.1128/jvi.01979-10] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report on the identification and characterization of XTERV1, a full-length endogenous retrovirus (ERV) within the genome of the western clawed frog (Xenopus tropicalis). XTERV1 contains all the basic genetic elements common to ERVs, including the classical 5'-long terminal repeat (LTR)-gag-pol-env-3'-LTR architecture, as well as conserved functional motifs inherent to each retroviral protein. Using phylogenetic analysis, we show that XTERV1 is related to the Epsilonretrovirus genus. The X. tropicalis genome harbors a single full-length copy with intact gag and pol open reading frames that localizes to the centromeric region of chromosome 5. About 10 full-length defective copies of XTERV1 are found interspersed in the genome, and 2 of them could be assigned to chromosomes 1 and 3. We find that XTERV1 genes are zygotically transcribed in a regulated spatiotemporal manner during frog development, including metamorphosis. Moreover, XTERV1 transcription is upregulated under certain cellular stress conditions, including cytotoxic and metabolic stresses. Interestingly, XTERV1 Env is found to be homologous to FR47, a protein upregulated following cold exposure in the freeze-tolerant wood frog (Rana sylvatica). In addition, we find that R. sylvatica FR47 mRNA originated from a retroviral element. We discuss the potential role(s) of ERVs in physiological processes in vertebrates.
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34
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Villarreal LP. The source of self: genetic parasites and the origin of adaptive immunity. Ann N Y Acad Sci 2009; 1178:194-232. [PMID: 19845639 DOI: 10.1111/j.1749-6632.2009.05020.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Stable colonization of the host by viruses (genetic parasites) can alter the systems of host identity and provide immunity against related viruses. To attain the needed stability, some viruses of prokaryotes (P1 phage) use a strategy called an addiction module. The linked protective and destructive gene functions of an addiction module insures both virus persistence but will also destroy cells that interrupt this module and thereby prevent infection by competitors. Previously, I have generalized this concept to also include persistent and lytic states of virus infection, which can be considered as a virus addiction module. Such states often involve defective viruses. In this report, I examine the origin of the adaptive immune system from the perspective of a virus addiction module. The likely role of both endogenous and exogenous retroviruses, DNA viruses, and their defective elements is considered in the origin of all the basal components of adaptive immunity (T-cell receptor, RAG-mediated gene rearrangement, clonal lymphocyte proliferation, antigen surface presentation, apoptosis, and education of immune cells). It is concluded that colonization by viruses and their defectives provides a more coherent explanation for the origin of adaptive immunity.
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Affiliation(s)
- Luis P Villarreal
- Center for Virus Research, Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, USA.
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35
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Carré-Eusèbe D, Coudouel N, Magre S. OVEX1, a novel chicken endogenous retrovirus with sex-specific and left-right asymmetrical expression in gonads. Retrovirology 2009; 6:59. [PMID: 19534790 PMCID: PMC2717909 DOI: 10.1186/1742-4690-6-59] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Accepted: 06/17/2009] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND In chickens, as in most birds, female gonad morphogenesis is asymmetrical. Gonads appear first rather similarly, but only the left one undergoes full differentiation and gives rise to a functional ovary. The right gonad, in which the cortex does not develop, remains restricted to the medulla and finally regresses. Opportunity was taken of this left-right asymmetry to perform a suppression subtractive hybridization screening to select for transcripts preferentially expressed in the developing left ovary as compared to the right one, and thus identify genes that are potentially involved in the process of ovarian differentiation. RESULTS One of these transcripts, named Ovex1 according to its expression profile, corresponds to an endogenous retrovirus that has not been previously characterized. It is transcribed as full-length and singly spliced mRNAs and contains three uninterrupted open reading frames coding potentially for proteins with homology to Gag and Pro-Pol retroviral polyproteins and a third protein showing only a weak similarity with Env glycoproteins. Ovex1 is severely degenerated; it is devoid of typical long terminal repeats and displays some evidence of recombination. An orthologous Ovex1 locus was identified in the genome of zebra finch, a member of a different bird order, and similar sequences were detected in turkey, guinea fowl, and duck DNA. The relationship between these sequences follows the bird phylogeny, suggesting vertical transmission of the endogenous retrovirus for more than 100 million years. Ovex1 is transcribed in chicken gonads with a sex-dependent and left-right asymmetrical pattern. It is first expressed in the cortex of the left indifferent gonads of both sexes. Expression is transient in the left testis and absent in the right one. In developing ovaries, Ovex1 transcription increases sharply in the left cortex and is weakly detected in the medulla. After folliculogenesis, Ovex1-expressing cells constitute the follicular granulosa cell layer. Ovex1 expression highlights a striking desquamation process that leads to profound cortical remodeling associated with follicle morphogenesis. CONCLUSION Evidence for a selection pressure at the protein level suggests that this endogenous retrovirus, expressed in the ovarian supporting cell lineage, might play an active role in bird ovarian physiology.
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Affiliation(s)
- Danièle Carré-Eusèbe
- Endocrinologie et Génétique de la Reproduction et du Développement, INSERM, U782, 32 rue des Carnets, F-92140, Clamart – France
- Univ. Paris-Sud, UMR-S0782, Clamart, F-92140
| | - Noëlline Coudouel
- Physiologie de l'Axe Gonadotrope, Unité de Biologie Fonctionnelle et Adaptative (BFA), Univ. PARIS 7 – CNRS, 4 rue MA Lagroua Weill-Hallé, 75205 Paris CEDEX 13 – France
| | - Solange Magre
- Physiologie de l'Axe Gonadotrope, Unité de Biologie Fonctionnelle et Adaptative (BFA), Univ. PARIS 7 – CNRS, 4 rue MA Lagroua Weill-Hallé, 75205 Paris CEDEX 13 – France
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36
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Ruiz S, Tafalla C, Cuesta A, Estepa A, Coll JM. In vitro search for alternative promoters to the human immediate early cytomegalovirus (IE-cMV) to express the G gene of viral haemorrhagic septicemia virus (VHSV) in fish epithelial cells. Vaccine 2009; 26:6620-9. [PMID: 18840493 DOI: 10.1016/j.vaccine.2008.09.048] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 09/06/2008] [Accepted: 09/15/2008] [Indexed: 11/18/2022]
Abstract
Present DNA vaccines against fish rhabdoviruses require intramuscular injection (fish-to-fish vaccination) of their G-protein gene under the control of the human immediate early cytomegalovirus (IE-CMV) promoter, while immersion delivery (mass DNA vaccination), for instance, by using fish epithelial-specific promoters, would be more practical for aquaculture. To find fish epithelial-specific promoters alternative to the IE-CMV, a comparative study of the effectiveness of different fish promoters constitutively expressing the G gene of the viral haemorrhagic septicemia virus (VHSV) in the epithelial papulosum cyprini (EPC) cell line was performed. The study included MCV1.4 (an alternative IE-CMV promoter version), AE6 (a version of the carp beta-actin promoter), long terminal repeats (LTR) of zebrafish or walleye retroviruses, trout Mx1, carp myosin-heavy-chain and flatfish pleurocidin promoters and salmonid sleeping beauty (SB)/medaka Tol2 transposon repeats. The G-protein expression in transfected EPC cells was studied by estimating the number of cells expressing the G-protein in their membrane and the average expression level per cell. In addition, in an attempt to reduce their sizes, some regions of the MCV1.4 and AE6 promoters were deleted and expression levels compared to those observed for full-length promoters. Since both zebrafish LTR and carp AE6 promoters were the most effective regulatory sequences for expressing the VHSV G-protein in EPC cells, these sequences might be candidates for new DNA vaccine vectors for fish epithelial tissues avoiding the IE-CMV promoter. Furthermore, known transcription factor binding sites (TFBS) common to most of the fish G-expressing promoters, might enable the future design of fully synthetic or hybrid promoters with improved efficacy of VHSV G-protein expression in epithelial fish cells.
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Affiliation(s)
- S Ruiz
- INIA, SGIT, Dept Biotecnología, Crt. Coruña Km 7, Madrid, Spain
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37
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Petit V, Vartanian JP, Wain-Hobson S. Powerful mutators lurking in the genome. Philos Trans R Soc Lond B Biol Sci 2009; 364:705-15. [PMID: 19042181 PMCID: PMC2660927 DOI: 10.1098/rstb.2008.0272] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The human genome encodes numerous enzymes capable of deaminating polynucleotides. While they are capable of exquisite specificity, occasionally they result in hypermutation where up to 90 per cent of cytidine or adenosine residues may be edited. As such, they constitute a formidable anti-viral barrier, for no virus can survive such a high mutation rate. As the APOBEC3 group of cytidine deaminases edit single-stranded viral DNA, the crucial question is can they hyperedit chromosomal DNA? Everything points to a positive answer. Nonetheless, hypermutants per se have not yet been described, probably being countered by highly efficient mismatch repair. For the APOBEC3 genes, not only is their physiological function unknown, but also their role in the induction of cancer remains to be determined. Yet given the pace of research, all this is certain to change in the next few years.
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Affiliation(s)
| | | | - Simon Wain-Hobson
- Molecular Retrovirology Unit, CNRS URA 3015, Institut Pasteur28 rue du Docteur Roux, 75724 Paris cedex 15, France
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38
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Transposable elements as drivers of genomic and biological diversity in vertebrates. Chromosome Res 2008; 16:203-15. [DOI: 10.1007/s10577-007-1202-6] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Paul TA, Quackenbush SL, Sutton C, Casey RN, Bowser PR, Casey JW. Identification and characterization of an exogenous retrovirus from atlantic salmon swim bladder sarcomas. J Virol 2006; 80:2941-8. [PMID: 16501103 PMCID: PMC1395439 DOI: 10.1128/jvi.80.6.2941-2948.2006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel piscine retrovirus has been identified in association with an outbreak of leiomyosarcoma in the swim bladders of Atlantic salmon. The complete nucleotide sequence of the Atlantic salmon swim bladder sarcoma virus (SSSV) provirus is 10.9 kb in length and shares a structure and transcriptional profile similar to those of murine leukemia virus-like simple retroviruses. SSSV appears unique to simple retroviruses by not harboring sequences in the Atlantic salmon genome. Additionally, SSSV differs from other retroviruses in potentially utilizing a methionine tRNA primer binding site. SSSV-associated tumors contain high proviral copy numbers (greater than 30 per cell) and a polyclonal integration pattern. Phylogenetic analysis based on reverse transcriptase places SSSV with zebrafish endogenous retrovirus (ZFERV) between the Gammaretrovirus and Epsilonretrovirus genera. Large regions of continuous homology between SSSV and ZFERV Gag, Pol, and Env suggest that these viruses represent a new group of related piscine retroviruses.
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Affiliation(s)
- Thomas A Paul
- Department of Microbiology and Immunology, C4137 VMC, Cornell University, Ithaca, New York 14853, USA
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40
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Tafalla C, Estepa A, Coll JM. Fish transposons and their potential use in aquaculture. J Biotechnol 2006; 123:397-412. [PMID: 16442657 DOI: 10.1016/j.jbiotec.2005.12.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Revised: 11/02/2005] [Accepted: 12/15/2005] [Indexed: 01/30/2023]
Abstract
A large part of repetitive DNA of vertebrate genomes have been identified as transposon elements (TEs) or mobile sequences. Although TEs detected to date in most vertebrates are inactivated, active TEs have been found in fish and a salmonid TE has been successfully reactivated by molecular genetic manipulation from inactive genomic copies (Sleeping Beauty, SB). Progress in the understanding of the dynamics, control and evolution of fish TEs will allow the insertion of selected sequences into the fish genomes of germ cells to obtain transgenics or to identify genes important for growth and/or of somatic cells to improve DNA vaccination. Expectations are high for new possible applications to fish of this well developed technology for mammals. Here, we review the present state of knowledge of inactive and active fish TEs and briefly discuss how their possible future applications might be used to improve fish production in aquaculture.
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Affiliation(s)
- C Tafalla
- CISA, Sanidad Animal, INIA, Valdeolmos, 28130 Madrid, Spain
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Blaise S, de Parseval N, Heidmann T. Functional characterization of two newly identified Human Endogenous Retrovirus coding envelope genes. Retrovirology 2005; 2:19. [PMID: 15766379 PMCID: PMC555746 DOI: 10.1186/1742-4690-2-19] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2005] [Accepted: 03/14/2005] [Indexed: 11/24/2022] Open
Abstract
A recent in silico search for coding sequences of retroviral origin present in the human genome has unraveled two new envelope genes that add to the 16 genes previously identified. A systematic search among the latter for a fusogenic activity had led to the identification of two bona fide genes, named syncytin-1 and syncytin-2, most probably co-opted by primate genomes for a placental function related to the formation of the syncytiotrophoblast by cell-cell fusion. Here, we show that one of the newly identified envelope gene, named envP(b), is fusogenic in an ex vivo assay, but that its expression – as quantified by real-time RT-PCR on a large panel of human tissues – is ubiquitous, albeit with a rather low value in most tissues. Conversely, the second envelope gene, named envV, discloses a placenta-specific expression, but is not fusogenic in any of the cells tested. Altogether, these results suggest that at least one of these env genes may play a role in placentation, but most probably through a process different from that of the two previously identified syncytins.
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Affiliation(s)
- Sandra Blaise
- Unité de Biologie des Rétrovirus, Département de Virologie, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris cedex 15, France
| | - Nathalie de Parseval
- Unité des Rétrovirus Endogènes et Eléments Rétroïdes des Eucaryotes Supérieurs, UMR 8122 CNRS, Institut Gustave Roussy, 39 rue Camille Desmoulins, 94805 Villejuif Cedex, France
| | - Thierry Heidmann
- Unité des Rétrovirus Endogènes et Eléments Rétroïdes des Eucaryotes Supérieurs, UMR 8122 CNRS, Institut Gustave Roussy, 39 rue Camille Desmoulins, 94805 Villejuif Cedex, France
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Villesen P, Aagaard L, Wiuf C, Pedersen FS. Identification of endogenous retroviral reading frames in the human genome. Retrovirology 2004; 1:32. [PMID: 15476554 PMCID: PMC524368 DOI: 10.1186/1742-4690-1-32] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2004] [Accepted: 10/11/2004] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Human endogenous retroviruses (HERVs) comprise a large class of repetitive retroelements. Most HERVs are ancient and invaded our genome at least 25 million years ago, except for the evolutionary young HERV-K group. The far majority of the encoded genes are degenerate due to mutational decay and only a few non-HERV-K loci are known to retain intact reading frames. Additional intact HERV genes may exist, since retroviral reading frames have not been systematically annotated on a genome-wide scale. RESULTS By clustering of hits from multiple BLAST searches using known retroviral sequences we have mapped 1.1% of the human genome as retrovirus related. The coding potential of all identified HERV regions were analyzed by annotating viral open reading frames (vORFs) and we report 7836 loci as verified by protein homology criteria. Among 59 intact or almost-intact viral polyproteins scattered around the human genome we have found 29 envelope genes including two novel gammaretroviral types. One encodes a protein similar to a recently discovered zebrafish retrovirus (ZFERV) while another shows partial, C-terminal, homology to Syncytin (HERV-W/FRD). CONCLUSIONS This compilation of HERV sequences and their coding potential provide a useful tool for pursuing functional analysis such as RNA expression profiling and effects of viral proteins, which may, in turn, reveal a role for HERVs in human health and disease. All data are publicly available through a database at http://www.retrosearch.dk.
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Affiliation(s)
- Palle Villesen
- Bioinformatics Research Center, University of Aarhus, Høegh-Guldbergs Gade 10, Bldg. 090, DK-8000 Aarhus, Denmark
| | - Lars Aagaard
- Bioinformatics Research Center, University of Aarhus, Høegh-Guldbergs Gade 10, Bldg. 090, DK-8000 Aarhus, Denmark
| | - Carsten Wiuf
- Bioinformatics Research Center, University of Aarhus, Høegh-Guldbergs Gade 10, Bldg. 090, DK-8000 Aarhus, Denmark
| | - Finn Skou Pedersen
- Department of Molecular Biology, University of Aarhus, C. F. Møllers Allé, Bldg. 130, DK-8000 Aarhus, Denmark
- Department of Medical Microbiology and Immunology, University of Aarhus, DK-8000 Aarhus, Denmark
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