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Li Y, Niu J, Liu Y, Dai Y, Ni H, Wang J, Fang R, Ye C. Genomic Sequencing and Analysis of Enzootic Nasal Tumor Virus Type 2 Provides Evidence for Recombination within the Prevalent Chinese Strains. Vet Sci 2024; 11:248. [PMID: 38921995 PMCID: PMC11209414 DOI: 10.3390/vetsci11060248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 05/22/2024] [Accepted: 05/30/2024] [Indexed: 06/27/2024] Open
Abstract
In recent years, the clinical cases of ENTV-2 infection have increased and become prevalent in several provinces of China. In this study, we reported the occurrence of ENTV-2 in one goat farm in Chongqing, southwest China. The complete genome of an emerged ENTV-2 isolate (designated as CQ2) was sequenced with 7468 bp in length. Phylogenetic analysis revealed that ENTV-2 consisted of two main lineages. Lineage 1 was composed of Chinese strains and could be subdivided into five sublineages. CQ2 and the other six recent isolates from China were clustered in sublineage 1.5; however, CQ2 was significantly different from the other six isolates. Furthermore, recombination analysis suggested that CQ2 might be a recombinant variant derived from sublineage 1.5 and sublineage 1.2 strains, with the recombination region in areas of pro and pol genes. In conclusion, we sequenced and analyzed the complete genome of a potential ENTV-2 recombinant, which may contribute to our understanding of the genetic variation and evolution of ENTV-2 in China.
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Affiliation(s)
- Yixuan Li
- Joint International Research Laboratory of Animal Health and Animal Food Safety, College of Veterinary Medicine, Southwest University, Chongqing 400715, China; (Y.L.); (J.N.); (Y.L.); (Y.D.); (R.F.)
| | - Jingyi Niu
- Joint International Research Laboratory of Animal Health and Animal Food Safety, College of Veterinary Medicine, Southwest University, Chongqing 400715, China; (Y.L.); (J.N.); (Y.L.); (Y.D.); (R.F.)
| | - Yiyu Liu
- Joint International Research Laboratory of Animal Health and Animal Food Safety, College of Veterinary Medicine, Southwest University, Chongqing 400715, China; (Y.L.); (J.N.); (Y.L.); (Y.D.); (R.F.)
| | - Yu Dai
- Joint International Research Laboratory of Animal Health and Animal Food Safety, College of Veterinary Medicine, Southwest University, Chongqing 400715, China; (Y.L.); (J.N.); (Y.L.); (Y.D.); (R.F.)
| | - Hongbo Ni
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China
| | - Jinliang Wang
- Shandong Binzhou Animal Science & Veterinary Medicine Academy, Binzhou 256600, China
| | - Rendong Fang
- Joint International Research Laboratory of Animal Health and Animal Food Safety, College of Veterinary Medicine, Southwest University, Chongqing 400715, China; (Y.L.); (J.N.); (Y.L.); (Y.D.); (R.F.)
| | - Chao Ye
- Joint International Research Laboratory of Animal Health and Animal Food Safety, College of Veterinary Medicine, Southwest University, Chongqing 400715, China; (Y.L.); (J.N.); (Y.L.); (Y.D.); (R.F.)
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Kemeter LM, Birzer A, Heym S, Thoma-Kress AK. Milk Transmission of Mammalian Retroviruses. Microorganisms 2023; 11:1777. [PMID: 37512949 PMCID: PMC10386362 DOI: 10.3390/microorganisms11071777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/02/2023] [Accepted: 07/05/2023] [Indexed: 07/30/2023] Open
Abstract
The transmission of viruses from one host to another typically occurs through horizontal or vertical pathways. The horizontal pathways include transmission amongst individuals, usually through bodily fluids or excretions, while vertical transmission transpires from mother to their offspring, either during pregnancy, childbirth, or breastfeeding. While there are more than 200 human pathogenic viruses to date, only a small number of them are known to be transmitted via breast milk, including cytomegalovirus (CMV), human immunodeficiency virus type 1 (HIV-1), and human T cell lymphotropic virus type 1 (HTLV-1), the latter two belonging to the family Retroviridae. Breast milk transmission is a common characteristic among mammalian retroviruses, but there is a lack of reports summarizing our knowledge regarding this route of transmission of mammalian retroviruses. Here, we provide an overview of the transmission of mammalian exogenous retroviruses with a focus on Orthoretrovirinae, and we highlight whether they have been described or suspected to be transmitted through breast milk, covering various species. We also elaborate on the production and composition of breast milk and discuss potential entry sites of exogenous mammalian retroviruses during oral transmission.
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Affiliation(s)
- Laura M Kemeter
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Alexandra Birzer
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Stefanie Heym
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Andrea K Thoma-Kress
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
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3
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van Vloten JP, Minott JA, McAusland TM, Ingrao JC, Santry LA, McFadden G, Petrik JJ, Bridle BW, Wootton SK. Production and purification of high-titer OrfV for preclinical studies in vaccinology and cancer therapy. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2021; 23:434-447. [PMID: 34786436 PMCID: PMC8579082 DOI: 10.1016/j.omtm.2021.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/03/2021] [Accepted: 08/10/2021] [Indexed: 11/29/2022]
Abstract
Poxviruses have been used extensively as vaccine vectors for human and veterinary medicine and have recently entered the clinical realm as immunotherapies for cancer. We present a comprehensive method for producing high-quality lots of the poxvirus Parapoxvirus ovis (OrfV) for use in preclinical models of vaccinology and cancer therapy. OrfV is produced using a permissive sheep skin-derived cell line and is released from infected cells by repeated freeze-thaw combined with sonication. We present two methods for isolation and purification of bulk virus. Isolated virus is concentrated to high titer using polyethylene glycol to produce the final in vivo-grade product. We also describe methods for quantifying OrfV infectious virions and determining genomic copy number to evaluate virus stocks. The methods herein will provide researchers with the ability to produce high-quality, high-titer OrfV for use in preclinical studies, and support the translation of OrfV-derived technologies into the clinic.
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Affiliation(s)
- Jacob P van Vloten
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Jessica A Minott
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Thomas M McAusland
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Joelle C Ingrao
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Lisa A Santry
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Grant McFadden
- The Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA
| | - James J Petrik
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Byram W Bridle
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Sarah K Wootton
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
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4
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Maeda N, Inoshima Y, De Las Heras M, Maenaka K. Enzootic nasal tumor virus type 2 envelope of goats acts as a retroviral oncogene in cell transformation. Virus Genes 2020; 57:50-59. [PMID: 33151445 DOI: 10.1007/s11262-020-01808-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/30/2020] [Indexed: 11/26/2022]
Abstract
Enzootic nasal tumor virus type 1 (ENTV-1) (ovine nasal tumor virus) and ENTV-2 (caprine nasal tumor virus) are known to be causative agents of enzootic nasal adenocarcinoma (ENA) in sheep and goats, respectively. Although the nucleotide and amino acid sequences of ENTV-1 and ENTV-2 are quite similar, they are recognized as phylogenetically distinct viruses. The envelope protein of ENTV-1 functions as an oncoprotein in the in vitro transformation of epithelial cells and fibroblasts. Thus, it is the primary determinant of in vivo tumorigenesis in ENA. As per our knowledge, no previous studies have reported in detail the role of ENTV-2 in ENA tumorigenesis. Here, in order to investigate the molecular mechanism of caprine ENA oncogenesis by ENTV-2, we have attempted to identify the transforming potential of ENTV-2 envelope, and investigated the activation of cell signaling pathways in oncogenic transformation. Our findings confirmed that ENTV-2 envelope was capable of inducing oncogenic transformation of rat cell lines in vitro. Further, we found that MAPK, Akt, and p38 were constitutively activated in ENTV-2 envelope-transformed clone cells. In addition, inhibitor experiments revealed that MEK-MAPK and PI3K-Akt signaling pathways are involved in the ENTV-2 envelope-induced cell transformation. These data indicate that ENTV-2 envelope could induce oncogenic transformation by signaling pathways that are also utilized by ENTV-1 envelope.
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Affiliation(s)
- Naoyoshi Maeda
- Center for Research and Education on Drug Discovery, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo, 060-0812, Japan.
| | - Yasuo Inoshima
- Laboratory of Food and Environmental Hygiene, Cooperative Department of Veterinary Medicine, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
| | | | - Katsumi Maenaka
- Center for Research and Education on Drug Discovery, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo, 060-0812, Japan
- Laboratory of Biomolecular Science, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo, 060-0812, Japan
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The U3 and Env Proteins of Jaagsiekte Sheep Retrovirus and Enzootic Nasal Tumor Virus Both Contribute to Tissue Tropism. Viruses 2019; 11:v11111061. [PMID: 31739606 PMCID: PMC6893448 DOI: 10.3390/v11111061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/12/2019] [Accepted: 11/12/2019] [Indexed: 12/11/2022] Open
Abstract
Jaagsiekte sheep retrovirus (JSRV) and enzootic nasal tumor virus (ENTV) are small-ruminant betaretroviruses that share high nucleotide and amino acid identity, utilize the same cellular receptor, hyaluronoglucosaminidase 2 (Hyal2) for entry, and transform tissues with their envelope (Env) glycoprotein; yet, they target discrete regions of the respiratory tract—the lung and nose, respectively. This distinct tissue selectivity makes them ideal tools with which to study the pathogenesis of betaretroviruses. To uncover the genetic determinants of tropism, we constructed JSRV–ENTV chimeric viruses and produced lentivectors pseudotyped with the Env proteins from JSRV (Jenv) and ENTV (Eenv). Through the transduction and infection of lung and nasal turbinate tissue slices, we observed that Hyal2 expression levels strongly influence ENTV entry, but that the long terminal repeat (LTR) promoters of these viruses are likely responsible for tissue-specificity. Furthermore, we show evidence of ENTV Env expression in chondrocytes within ENTV-infected nasal turbinate tissue, where Hyal2 is highly expressed. Our work suggests that the unique tissue tropism of JSRV and ENTV stems from the combined effort of the envelope glycoprotein-receptor interactions and the LTR and provides new insight into the pathogenesis of ENTV.
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A Cell Fusion-Based Screening Method Identifies Glycosylphosphatidylinositol-Anchored Protein Ly6e as the Receptor for Mouse Endogenous Retroviral Envelope Syncytin-A. J Virol 2017; 91:JVI.00832-17. [PMID: 28679758 DOI: 10.1128/jvi.00832-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 06/28/2017] [Indexed: 11/20/2022] Open
Abstract
Syncytin genes are envelope genes of retroviral origin that have been exapted for a role in placentation. They are involved in the formation of a syncytial structure (the syncytiotrophoblast) at the fetomaternal interface via their fusogenic activity. The mouse placenta is unique among placental mammals since the fetomaternal interface comprises two syncytiotrophoblast layers (ST-I and ST-II) instead of one, as observed in humans and all other hemochorial placentae. Each layer specifically expresses a distinct mouse syncytin, namely, syncytin-A (SynA) for ST-I and syncytin-B (SynB) for ST-II, which have been shown to be essential to placentogenesis and embryo survival. Their cognate cellular receptors, which are necessary to mediate cell-cell fusion and syncytiotrophoblast formation, are still unknown. By devising a sensitive method that combines a cell-cell fusion assay with the screening of a mouse cDNA library, we succeeded in identifying the glycosylphosphatidylinositol (GPI)-anchored membrane protein lymphocyte antigen 6E (Ly6e) as a candidate receptor for SynA. Transfection of cells with the cloned receptor led to their fusion to cells expressing SynA, with no cross-reactive fusion activity with SynB. Knocking down Ly6e greatly reduced SynA-induced cell fusion, thus suggesting that Ly6e is the sole receptor for SynA in vivo Interaction of SynA with Ly6e was further demonstrated by a competition assay using the soluble ectodomain of Ly6e. Finally, reverse transcription-quantitative PCR (RT-qPCR) analysis of Ly6e expression on a representative panel of mouse tissues shows that it is significantly expressed in the mouse placenta together with SynA.IMPORTANCE Syncytin genes are envelope genes of endogenous retroviruses, co-opted for a physiological function in placentation. Syncytins are fusogenic proteins that mediate cell-cell fusion by interacting with receptors present on the partner cells. Here, by devising a sensitive in vitro fusion assay that enables the high-throughput screening of normalized cDNA libraries, we identified the long-sought receptor for syncytin-A (SynA), a mouse syncytin responsible for syncytiotrophoblast formation at the maternofetal interface of the mouse placenta. This protein, Ly6e (lymphocyte antigen 6E), is a GPI-anchored membrane protein, and small interfering RNA (siRNA) experiments targeting its deletion as well as a decoy assay using a recombinant soluble receptor show that Ly6e is the necessary and sufficient partner of SynA. Its profile of expression is consistent with a role in both ancestral endogenization of a SynA founder retrovirus and present-day placenta formation. This study provides a powerful general method to identify genes involved in cell-cell fusion processes.
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Walsh SR, de Jong JG, van Vloten JP, Gerpe MCR, Santry LA, Wootton SK. Truncation of the enzootic nasal tumor virus envelope protein cytoplasmic tail increases Env-mediated fusion and infectivity. J Gen Virol 2017; 98:108-120. [PMID: 27902399 DOI: 10.1099/jgv.0.000654] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Enzootic nasal tumor virus (ENTV) and Jaagsiekte sheep retrovirus (JSRV) are highly related ovine betaretroviruses that induce nasal and lung tumours in small ruminants, respectively. While the ENTV and JSRV envelope (Env) glycoproteins mediate virus entry using the same cellular receptor, the glycosylphosphatidylinositol-linked protein hyaluronoglucosaminidase, ENTV Env pseudovirions mediate entry into cells from a much more restricted range of species than do JSRV Env pseudovirions. Unlike JSRV Env, ENTV Env does not induce cell fusion at pH 5.0 or above, but rather requires a much lower pH (4.0-4.5) for fusion to occur. The cytoplasmic tail of retroviral envelope proteins is a key modulator of envelope-mediated fusion and pseudotype efficiency, especially in the context of virions composed of heterologous Gag proteins. Here we report that progressive truncation of the ENTV Env cytoplasmic tail improves transduction efficiency of pseudotyped retroviral vectors and that complete truncation of the ENTV Env cytoplasmic tail increases transduction efficiency to wild-type JSRV Env levels by increasing fusogenicity without affecting sensitivity to inhibition by lysosomotropic agents, subcellular localization or efficiency of inclusion into virions. Truncation of the cytoplasmic domain of ENTV Env resulted in a significant advantage in viral entry into all cell types tested, including foetal ovine lung and nasal cells. Taken together, we demonstrate that the cytoplasmic tail modulates the fusion activity of the ENTV Env protein and that truncation of this region enhances Eenv-mediated entry into target cells.
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Affiliation(s)
- Scott R Walsh
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Jondavid G de Jong
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Jacob P van Vloten
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | | | - Lisa A Santry
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Sarah K Wootton
- Present address: McMaster Immunology Research Centre, McMaster University, Hamilton, ON, Canada.,Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
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Youssef G, Wallace WAH, Dagleish MP, Cousens C, Griffiths DJ. Ovine pulmonary adenocarcinoma: a large animal model for human lung cancer. ILAR J 2016; 56:99-115. [PMID: 25991702 DOI: 10.1093/ilar/ilv014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Lung cancer is the leading cause of cancer deaths worldwide. Recent progress in understanding the molecular pathogenesis of this disease has resulted in novel therapeutic strategies targeting specific groups of patients. Further studies are required to provide additional advances in diagnosis and treatment. Animal models are valuable tools for studying oncogenesis in lung cancer, particularly during the early stages of disease where tissues are rarely available from human cases. Mice have traditionally been used for studying lung cancer in vivo, and a variety of spontaneous and transgenic models are available. However, it is recognized that other species may also be informative for studies of cancer. Ovine pulmonary adenocarcinoma (OPA) is a naturally occurring lung cancer of sheep caused by retrovirus infection and has several features in common with adenocarcinoma of humans, including a similar histological appearance and activation of common cell signaling pathways. Additionally, the size and organization of human lungs are much closer to those of sheep lungs than to those of mice, which facilitates experimental approaches in sheep that are not available in mice. Thus OPA presents opportunities for studying lung tumor development that can complement conventional murine models. Here we describe the potential applications of OPA as a model for human lung adenocarcinoma with an emphasis on the various in vivo and in vitro experimental systems available.
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Affiliation(s)
- Gehad Youssef
- Gehad Youssef, BSc, is a research scientist at the Moredun Research Institute, Edinburgh, UK. William A. H. Wallace, MBChB(Hons), PhD, FRCPE, FRCPath, is a consultant pathologist at the Royal Infirmary of Edinburgh and Honorary Reader in Pathology, Edinburgh University, UK; Mark P. Dagleish BVM&S, PhD, MRCVS, FRCPath, is Head of Pathology at the Moredun Research Institute, Edinburgh, UK. Chris Cousens, PhD, is a senior research scientist at the Moredun Research Institute, Edinburgh, UK, and David J. Griffiths, PhD, is a principal research scientist at the Moredun Research Institute, Edinburgh, UK
| | - William A H Wallace
- Gehad Youssef, BSc, is a research scientist at the Moredun Research Institute, Edinburgh, UK. William A. H. Wallace, MBChB(Hons), PhD, FRCPE, FRCPath, is a consultant pathologist at the Royal Infirmary of Edinburgh and Honorary Reader in Pathology, Edinburgh University, UK; Mark P. Dagleish BVM&S, PhD, MRCVS, FRCPath, is Head of Pathology at the Moredun Research Institute, Edinburgh, UK. Chris Cousens, PhD, is a senior research scientist at the Moredun Research Institute, Edinburgh, UK, and David J. Griffiths, PhD, is a principal research scientist at the Moredun Research Institute, Edinburgh, UK
| | - Mark P Dagleish
- Gehad Youssef, BSc, is a research scientist at the Moredun Research Institute, Edinburgh, UK. William A. H. Wallace, MBChB(Hons), PhD, FRCPE, FRCPath, is a consultant pathologist at the Royal Infirmary of Edinburgh and Honorary Reader in Pathology, Edinburgh University, UK; Mark P. Dagleish BVM&S, PhD, MRCVS, FRCPath, is Head of Pathology at the Moredun Research Institute, Edinburgh, UK. Chris Cousens, PhD, is a senior research scientist at the Moredun Research Institute, Edinburgh, UK, and David J. Griffiths, PhD, is a principal research scientist at the Moredun Research Institute, Edinburgh, UK
| | - Chris Cousens
- Gehad Youssef, BSc, is a research scientist at the Moredun Research Institute, Edinburgh, UK. William A. H. Wallace, MBChB(Hons), PhD, FRCPE, FRCPath, is a consultant pathologist at the Royal Infirmary of Edinburgh and Honorary Reader in Pathology, Edinburgh University, UK; Mark P. Dagleish BVM&S, PhD, MRCVS, FRCPath, is Head of Pathology at the Moredun Research Institute, Edinburgh, UK. Chris Cousens, PhD, is a senior research scientist at the Moredun Research Institute, Edinburgh, UK, and David J. Griffiths, PhD, is a principal research scientist at the Moredun Research Institute, Edinburgh, UK
| | - David J Griffiths
- Gehad Youssef, BSc, is a research scientist at the Moredun Research Institute, Edinburgh, UK. William A. H. Wallace, MBChB(Hons), PhD, FRCPE, FRCPath, is a consultant pathologist at the Royal Infirmary of Edinburgh and Honorary Reader in Pathology, Edinburgh University, UK; Mark P. Dagleish BVM&S, PhD, MRCVS, FRCPath, is Head of Pathology at the Moredun Research Institute, Edinburgh, UK. Chris Cousens, PhD, is a senior research scientist at the Moredun Research Institute, Edinburgh, UK, and David J. Griffiths, PhD, is a principal research scientist at the Moredun Research Institute, Edinburgh, UK
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Infectious Entry Pathway Mediated by the Human Endogenous Retrovirus K Envelope Protein. J Virol 2016; 90:3640-9. [PMID: 26792739 DOI: 10.1128/jvi.03136-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 01/12/2016] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Endogenous retroviruses (ERVs), the majority of which exist as degraded remnants of ancient viruses, comprise approximately 8% of the human genome. The youngest human ERVs (HERVs) belong to the HERV-K(HML-2) subgroup and were endogenized within the past 1 million years. The viral envelope protein (ENV) facilitates the earliest events of endogenization (cellular attachment and entry), and here, we characterize the requirements for HERV-K ENV to mediate infectious cell entry. Cell-cell fusion assays indicate that a minimum of two events are required for fusion, proteolytic processing by furin-like proteases and exposure to acidic pH. We generated an infectious autonomously replicating recombinant vesicular stomatitis virus (VSV) in which the glycoprotein was replaced by HERV-K ENV. HERV-K ENV imparts an endocytic entry pathway that requires dynamin-mediated membrane scission and endosomal acidification but is distinct from clathrin-dependent or macropinocytic uptake pathways. The lack of impediments to the replication of the VSV core in eukaryotic cells allowed us to broadly survey the HERV-K ENV-dictated tropism. Unlike extant betaretroviral envelopes, which impart a narrow species tropism, we found that HERV-K ENV mediates broad tropism encompassing cells from multiple mammalian and nonmammalian species. We conclude that HERV-K ENV dictates an evolutionarily conserved entry pathway and that the restriction of HERV-K to primate genomes reflects downstream stages of the viral replication cycle. IMPORTANCE Approximately 8% of the human genome is of retroviral origin. While many of those viral genomes have become inactivated, some copies of the most recently endogenized human retrovirus, HERV-K, can encode individual functional proteins. Here, we characterize the envelope protein (ENV) of the virus to define how it mediates infection of cells. We demonstrate that HERV-K ENV undergoes a proteolytic processing step and triggers membrane fusion in response to acidic pH--a strategy common to many viral fusogens. Our data suggest that the infectious entry pathway mediated by this ENV requires endosomal acidification and the GTPase dynamin but does not require clathrin-dependent uptake. In marked contrast to other betaretroviruses, HERV-K ENV imparts broad species tropism in cultured cells. This work provides new insights into the entry pathway of an extinct human virus and provides a powerful tool to further probe the endocytic route by which HERV-K infects cells.
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12
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Affiliation(s)
- A Dusty Miller
- Fred Hutchinson Cancer Research Center , Seattle, WA 98109
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13
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Monot M, Archer F, Gomes M, Mornex JF, Leroux C. Advances in the study of transmissible respiratory tumours in small ruminants. Vet Microbiol 2015; 181:170-7. [PMID: 26340900 DOI: 10.1016/j.vetmic.2015.08.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Sheep and goats are widely infected by oncogenic retroviruses, namely Jaagsiekte Sheep RetroVirus (JSRV) and Enzootic Nasal Tumour Virus (ENTV). Under field conditions, these viruses induce transformation of differentiated epithelial cells in the lungs for Jaagsiekte Sheep RetroVirus or the nasal cavities for Enzootic Nasal Tumour Virus. As in other vertebrates, a family of endogenous retroviruses named endogenous Jaagsiekte Sheep RetroVirus (enJSRV) and closely related to exogenous Jaagsiekte Sheep RetroVirus is present in domestic and wild small ruminants. Interestingly, Jaagsiekte Sheep RetroVirus and Enzootic Nasal Tumour Virus are able to promote cell transformation, leading to cancer through their envelope glycoproteins. In vitro, it has been demonstrated that the envelope is able to deregulate some of the important signaling pathways that control cell proliferation. The role of the retroviral envelope in cell transformation has attracted considerable attention in the past years, but it appears to be highly dependent of the nature and origin of the cells used. Aside from its health impact in animals, it has been reported for many years that the Jaagsiekte Sheep RetroVirus-induced lung cancer is analogous to a rare, peculiar form of lung adenocarcinoma in humans, namely lepidic pulmonary adenocarcinoma. The implication of a retrovirus related to Jaagsiekte Sheep RetroVirus is still controversial and under investigation, but the identification of an infectious agent associated with the development of lepidic pulmonary adenocarcinomas might help us to understand cancer development. This review explores the mechanisms of induction of respiratory cancers in small ruminants and the possible link between retrovirus and lepidic pulmonary adenocarcinomas in humans.
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Affiliation(s)
- M Monot
- INRA UMR754-Université Lyon 1, Retrovirus and Comparative Pathology, France; Université de Lyon, France
| | - F Archer
- INRA UMR754-Université Lyon 1, Retrovirus and Comparative Pathology, France; Université de Lyon, France
| | - M Gomes
- INRA UMR754-Université Lyon 1, Retrovirus and Comparative Pathology, France; Université de Lyon, France
| | - J-F Mornex
- INRA UMR754-Université Lyon 1, Retrovirus and Comparative Pathology, France; Université de Lyon, France; Hospices Civils de Lyon, France
| | - C Leroux
- INRA UMR754-Université Lyon 1, Retrovirus and Comparative Pathology, France; Université de Lyon, France.
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Role for a Zinc Finger Protein (Zfp111) in Transformation of 208F Rat Fibroblasts by Jaagsiekte Sheep Retrovirus Envelope Protein. J Virol 2015; 89:10453-66. [PMID: 26246563 DOI: 10.1128/jvi.01631-15] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 07/29/2015] [Indexed: 01/15/2023] Open
Abstract
UNLABELLED The native envelope gene (env) of Jaagsiekte sheep retrovirus (JSRV) also acts as an oncogene. To investigate the mechanism of transformation, we performed yeast 2-hybrid screening for cellular proteins that interact with Env. Among several candidates, we identified mouse or rat zinc finger protein 111 (zfp111). The interaction between Env and Zfp111 was confirmed through in vivo coimmunoprecipitation assays. Knockdown of endogenous Zfp111 caused a decrease in cell transformation by JSRV Env, while overexpression of Zfp111 increased overall Env transformation, supporting a role for Zfp111 in Env transformation. Knockdown of Zfp111 had no effect on the growth rate of parental rat 208F cells, while it decreased the proliferation rate of JSRV-transformed 208F cells, suggesting that JSRV-transformed cells became dependent on Zfp111. In addition, Zfp111 preferentially bound to a higher-mobility form of JSRV Env that has not been described previously. The higher-mobility form of Env (P70(env)) was found exclusively in the nuclear fraction, and size of its polypeptide backbone was the same as that of the cytoplasmic Env polyprotein (Pr80(env)). The differences in glycosylation between the two versions of Env were characterized. These results identify a novel cellular protein, Zfp111, that binds to the JSRV Env protein, and this binding plays a role in Env transformation. These results indicate that JSRV transformation also involves proteins and interactions in the nucleus. IMPORTANCE The envelope protein (Env) of Jaagsiekte sheep retrovirus (JSRV) is an oncogene, but its mechanism of cell transformation is still unclear. Here we identified seven candidate cellular proteins that can interact with JSRV Env by yeast two-hybrid screening. This study focused on one of the seven candidates, zinc finger protein 111 (Zfp111). Zfp111 was shown to interact with JSRV Env in cells and to be involved in JSRV transformation. Moreover, coexpression of JSRV Env and Zfp111 led to the identification of a novel nuclear form of the JSRV Env protein that binds Zfp111. Nuclear Env was found to differ by glycosylation from the cytoplasmic Env precursor to the virion envelope proteins. These results suggest that JSRV Env transformation may involve nuclear events such as an alteration in transcription mediated by Env-Zfp111 interactions.
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Eckstrand CD, Castillo D, McDonnel SJ, Hillman CN, Vapniarsky N, Shanthalingam S, de las Heras M, Murphy BG. Genetic variability and in vitro transcriptional permissibility of primary ovine beta-retrovirus promoter isolates. Am J Vet Res 2014; 74:1421-7. [PMID: 24168308 DOI: 10.2460/ajvr.74.11.1421] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To assess genomic sequence conservation and variation in the proviral promoter of enzootic nasal tumor virus (ENTV) and Jaagsiekte sheep retrovirus (JSRV) in tissue samples from 3 sheep with nasal adenocarcinoma associated with ENTV and 3 sheep with pulmonary adenocarcinoma associated with JSRV and to identify a cell culture system that supports transcriptional activity of the ENTV and JSRV viral promoters. ANIMALS 6 adult sheep. PROCEDURES Standard PCR procedures for detection of the ENTV and JSRV long terminal repeat (LTR) promoter region were performed on samples from the 3 nasal adenocarcinomas and 3 pulmonary adenocarcinomas, respectively. The LTRs were cloned into shuttle vectors, amplified, sequenced, and analyzed. The cloned LTR regions were transferred into reporter plasmids and multiple human and ruminant cell lines, and primary cells were transfected with the promoter-reporter plasmids. The viral promoter activity was evaluated by use of an in vitro β-galactosidase reporter assay. RESULTS Each isolate had a unique nucleotide sequence. Single nucleotide polymorphisms were the most common LTR mutation and rarely occurred at transcription factor binding sites. Relative to ENTV, the JSRV promoter isolates had a conserved 66-bp U3 insertion, including the lung-specific transcription factor HNF-3β binding site. Among the cell lines used, human embryonic kidney (293T) and goat synovial membrane cells supported promoter transcription. CONCLUSIONS AND CLINICAL RELEVANCE The LTRs of ENTV and JSRV have extensive blocks of sequence conservation. Human 293T and goat synovial membrane cell lines may be suitable in vitro cell culture systems for further research of viral promoter functions.
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Affiliation(s)
- Christina D Eckstrand
- Department of Pathology, Microbiology & Immunology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616
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Jaagsiekte sheep retrovirus detected in human lung cancer tissue arrays. BMC Res Notes 2014; 7:160. [PMID: 24642139 PMCID: PMC3995318 DOI: 10.1186/1756-0500-7-160] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 03/13/2014] [Indexed: 01/15/2023] Open
Abstract
Background Adenocarcinoma is the most common type of non-small cell lung cancer and is frequently observed in non-smoking patients. Adenocarcinoma in-situ (formerly referred to as bronchioloalveolar carcinoma) is a subset of lung adenocarcinoma characterized by growth along alveolar septae without evidence of stromal, vascular, or pleural invasion, that disproportionately affects never-smokers, women, and Asians. Adenocarcinoma in-situ is morphologically and histologically similar to a contagious lung neoplasm of sheep called ovine pulmonary adenocarcinoma (OPA). OPA is caused by infection with the exogenous betaretrovirus, jaagsiekte sheep retrovirus (JSRV), whose envelope protein (Env) is a potent oncogene. Several studies have reported that a proportion of human lung adenocarcinomas are immunopositive for an antigen related to the Gag protein of JSRV, however other groups have been unable to verify these observations by PCR. Methods Here we examine human lung cancer tissue arrays (TA) for evidence of JSRV Env protein and DNA by immunohistochemical staining and PCR, respectively. Results Our results reveal that a subset of human lung cancers express an antigen that reacts with a JSRV Env-specific monoclonal antibody in immunohistochemistry and that exogenous JSRV-like env and gag sequences can be amplified from TA tumor samples, albeit inefficiently. Conclusions While a causative role has not been established, these data suggest that a JSRV-like virus might infect humans. With next generation sequencing approaches, a JSRV-like virus in human lung cancers may be identified which could have profound implications for prevention, diagnosis and therapy.
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Walsh SR, Linnerth-Petrik NM, Yu DL, Foster RA, Menzies PI, Diaz-Méndez A, Chalmers HJ, Wootton SK. Experimental transmission of enzootic nasal adenocarcinoma in sheep. Vet Res 2013; 44:66. [PMID: 23899161 PMCID: PMC3734154 DOI: 10.1186/1297-9716-44-66] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 07/26/2013] [Indexed: 12/21/2022] Open
Abstract
Enzootic nasal adenocarcinoma (ENA) is a contagious neoplasm of the secretory epithelial cells of the nasal mucosa of sheep and goats. It is associated with the betaretrovirus, enzootic nasal tumor virus (ENTV), but a causative relationship has yet to be demonstrated. In this study, 14-day-old lambs were experimentally infected via nebulization with cell-free tumor filtrates derived from naturally occurring cases of ENA. At 12 weeks post-infection (wpi), one of the five infected lambs developed clinical signs, including continuous nasal discharge and open mouth breathing, and was euthanized. Necropsy revealed the presence of a large bilateral tumor occupying the nasal cavity. At 45 wpi, when the study was terminated, none of the remaining infected sheep showed evidence of tumors either by computed tomography or post-mortem examination. ENTV-1 proviral DNA was detected in the nose, lung, spleen, liver and kidney of the animal with experimentally induced ENA, however there was no evidence of viral protein expression in tissues other than the nose. Density gradient analysis of virus particles purified from the experimentally induced nasal tumor revealed a peak reverse transcriptase (RT) activity at a buoyant density of 1.22 g/mL which was higher than the 1.18 g/mL density of peak RT activity of virus purified from naturally induced ENA. While the 1.22 g/mL fraction contained primarily immature unprocessed virus particles, mature virus particles with a similar morphology to naturally occurring ENA could be identified by electron microscopy. Full-length sequence analysis of the ENTV-1 genome from the experimentally induced tumor revealed very few nucleotide changes relative to the original inoculum with only one conservative amino acid change. Taken together, these results demonstrate that ENTV-1 is associated with transmissible ENA in sheep and that under experimental conditions, lethal tumors are capable of developing in as little as 12 wpi demonstrating the acutely oncogenic nature of this ovine betaretrovirus.
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Hull S, Lim J, Hamil A, Nitta T, Fan H. Analysis of jaagsiekte sheep retrovirus (JSRV) envelope protein domains in transformation. Virus Genes 2012; 45:508-17. [PMID: 22864547 DOI: 10.1007/s11262-012-0793-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 07/18/2012] [Indexed: 12/01/2022]
Abstract
Jaagsiekte sheep retrovirus (JSRV) is the causative agent of a transmissible lung cancer in sheep. A unique feature is that JSRV envelope protein is also the oncogene for this virus. Previous studies have identified the cytoplasmic tail (CT) of the envelope transmembrane (TM) protein as critical for transformation although other regions of Env have also been implicated. In this study, the roles of other Env regions in transformation were investigated. Chimeras between JSRV Env and the Env of a related non-oncogenic endogenous retrovirus (enJSRV, 5F16) were used. A chimera containing the membrane-spanning region (MSR) of enJSRV inserted into JSRV Env showed substantially reduced transformation, indicating that the MSR plays a role in transformation. Transformation by this chimera was highly dependent on both Ras/Raf/MEK/MAPK and PI3K/Akt/mTOR signaling. A chimera containing the two amino acids in the TM ectodomain that distinguish JSRV and enJSRV showed modestly reduced transformation. Chimeras in the SU protein indicated that the amino terminal region of SU contributes to transformation, while the C-terminal part is not important. To test if Env trimerization is important for transformation, we mutated a leucine-rich sequence in the putative trimerization domain in the ectodomain of TM (Tri-M). This mutant could not transform cells and it did not oligomerize. However, Tri-M could complement a non-transforming mutant CT mutant (Y590F) so oligomerization is not necessary for at least some aspects of transformation. These experiments provide new insight into the regions and residues of JSRV Env protein necessary for oncogenic transformation.
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Affiliation(s)
- Stacey Hull
- Cancer Research Institute, Sprague Hall, University of California-Irvine, CA 92697-3900, USA
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Lutringer-Magnin D, Girard N, Cadranel J, Leroux C, Quoix E, Cottin V, Signore CD, Lebitasy MP, Cordier G, Vanhems P, Mornex JF. Professional exposure to goats increases the risk of pneumonic-type lung adenocarcinoma: results of the IFCT-0504-Epidemio study. PLoS One 2012; 7:e37889. [PMID: 22655078 PMCID: PMC3360000 DOI: 10.1371/journal.pone.0037889] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2012] [Accepted: 04/30/2012] [Indexed: 12/14/2022] Open
Abstract
Pneumonic-type lung adenocarcinoma (P-ADC) represents a distinct subset of lung cancer with specific clinical, radiological, and pathological features. Given the weak association with tobacco-smoking and the striking similarities with jaagsiekte sheep retrovirus (JSRV)-induced ovine pulmonary adenocarcinoma, it has been suggested that a zoonotic viral agent infecting pulmonary cells may predispose to P-ADC in humans. Our objective was to explore whether exposure to domestic small ruminants may represent a risk factor for P-ADC. We performed a multicenter case-control study recruiting patients with P-ADC as cases and patients with non-P-ADC non-small cell lung cancer as controls. A dedicated 356-item questionnaire was built to evaluate exposure to livestock. A total of 44 cases and 132 controls were included. At multivariate analysis, P-ADC was significantly more associated with female gender (Odds-ratio (OR) = 3.23, 95% confidence interval (CI): 1.32–7.87, p = 0.010), never- smoker status (OR = 3.57, 95% CI: 1.27–10.00, p = 0.015), personal history of extra-thoracic cancer before P-ADC diagnosis (OR = 3.43, 95% CI: 1.10–10.72, p = 0.034), and professional exposure to goats (OR = 5.09, 95% CI: 1.05–24.69, p = 0.043), as compared to other subtypes of lung cancer. This case-control suggests a link between professional exposure to goats and P-ADC, and prompts for further epidemiological evaluation of potential environmental risk factors for P-ADC.
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Affiliation(s)
- Delphine Lutringer-Magnin
- Hospices Civils de Lyon, Lyon, France
- Université de Lyon, Lyon, France
- Université Claude Bernard Lyon 1, Lyon, France
- UMR 5558 CNRS, Laboratoire de biométrie et biologie évolutive, Lyon, France
| | - Nicolas Girard
- Hospices Civils de Lyon, Lyon, France
- Université de Lyon, Lyon, France
- Université Claude Bernard Lyon 1, Lyon, France
- UMR754 INRA, Rétrovirus et pathologie comparée, Lyon, France
| | | | - Caroline Leroux
- Université de Lyon, Lyon, France
- Université Claude Bernard Lyon 1, Lyon, France
- UMR754 INRA, Rétrovirus et pathologie comparée, Lyon, France
| | - Elisabeth Quoix
- Service de pneumologie, Hôpital Hautepierre, Strasbourg, France
| | - Vincent Cottin
- Hospices Civils de Lyon, Lyon, France
- Université de Lyon, Lyon, France
- Université Claude Bernard Lyon 1, Lyon, France
- UMR754 INRA, Rétrovirus et pathologie comparée, Lyon, France
| | - Corinne Del Signore
- Université de Lyon, Lyon, France
- Université Claude Bernard Lyon 1, Lyon, France
- UMR 5558 CNRS, Laboratoire de biométrie et biologie évolutive, Lyon, France
| | | | - Geneviève Cordier
- Université de Lyon, Lyon, France
- Université Claude Bernard Lyon 1, Lyon, France
- UMR754 INRA, Rétrovirus et pathologie comparée, Lyon, France
| | - Philippe Vanhems
- Hospices Civils de Lyon, Lyon, France
- Université de Lyon, Lyon, France
- Université Claude Bernard Lyon 1, Lyon, France
- UMR 5558 CNRS, Laboratoire de biométrie et biologie évolutive, Lyon, France
| | - Jean-François Mornex
- Hospices Civils de Lyon, Lyon, France
- Université de Lyon, Lyon, France
- Université Claude Bernard Lyon 1, Lyon, France
- UMR754 INRA, Rétrovirus et pathologie comparée, Lyon, France
- * E-mail:
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Côté M, Zheng YM, Li K, Xiang SH, Albritton LM, Liu SL. Critical role of leucine-valine change in distinct low pH requirements for membrane fusion between two related retrovirus envelopes. J Biol Chem 2012; 287:7640-51. [PMID: 22235118 PMCID: PMC3293530 DOI: 10.1074/jbc.m111.334722] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 01/10/2012] [Indexed: 01/03/2023] Open
Abstract
Many viruses use a pH-dependent pathway for fusion with host cell membrane, the mechanism of which is still poorly understood. Here we report that a subtle leucine (Leu)-valine (Val) change at position 501 in the envelope glycoproteins (Envs) of two related retroviruses, jaagsiekte sheep retrovirus (JSRV) and enzootic nasal tumor virus (ENTV), is responsible for their distinct low pH requirements for membrane fusion and infection. The Leu and Val residues are predicted to reside within the C-terminal heptad repeat (HR2) region of JSRV and ENTV Envs, particularly proximal to the hairpin turn of the putative six-helix bundle (6HB). Substitution of the JSRV Leu with a Val blocked the Env-mediated membrane fusion at pH 5.0, whereas replacement of the ENTV Val with a Leu rendered the ENTV Env capable of fusing at pH 5.0. A Leu-Val change has no apparent effect on the stability of native Env, but appears to stabilize an intermediate induced by receptor binding. These results are consistent with the existence of at least two metastable conformations of these viral glycoproteins, the native prefusion conformation and a receptor-induced metastable intermediate. Collectively, this work represents an interesting perhaps unique example whereby a simple Leu-Val change has critical impact on pH-dependent virus fusion and entry.
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Affiliation(s)
- Marceline Côté
- the Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Yi-Min Zheng
- From the Department of Molecular Microbiology and Immunology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - Kun Li
- From the Department of Molecular Microbiology and Immunology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - Shi-Hua Xiang
- the Nebraska Center for Virology, School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68583, and
| | - Lorraine M. Albritton
- the Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Shan-Lu Liu
- From the Department of Molecular Microbiology and Immunology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
- the Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada
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Morrison WB. Inflammation and cancer: a comparative view. J Vet Intern Med 2011; 26:18-31. [PMID: 22151229 DOI: 10.1111/j.1939-1676.2011.00836.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 09/22/2011] [Accepted: 10/05/2011] [Indexed: 12/11/2022] Open
Abstract
Rudolph Virchow first speculated on a relationship between inflammation and cancer more than 150 years ago. Subsequently, chronic inflammation and associated reactive free radical overload and some types of bacterial, viral, and parasite infections that cause inflammation were recognized as important risk factors for cancer development and account for one in four of all human cancers worldwide. Even viruses that do not directly cause inflammation can cause cancer when they act in conjunction with proinflammatory cofactors or when they initiate or promote cancer via the same signaling pathways utilized in inflammation. Whatever its origin, inflammation in the tumor microenvironment has many cancer-promoting effects and aids in the proliferation and survival of malignant cells and promotes angiogenesis and metastasis. Mediators of inflammation such as cytokines, free radicals, prostaglandins, and growth factors can induce DNA damage in tumor suppressor genes and post-translational modifications of proteins involved in essential cellular processes including apoptosis, DNA repair, and cell cycle checkpoints that can lead to initiation and progression of cancer.
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Affiliation(s)
- Wallace B Morrison
- Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, IN, USA.
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22
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Côté M, Zheng YM, Albritton LM, Liu SL. Single residues in the surface subunits of oncogenic sheep retrovirus envelopes distinguish receptor-mediated triggering for fusion at low pH and infection. Virology 2011; 421:173-83. [PMID: 22018783 DOI: 10.1016/j.virol.2011.09.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2011] [Revised: 09/13/2011] [Accepted: 09/24/2011] [Indexed: 11/25/2022]
Abstract
Jaagsiekte sheep retrovirus (JSRV) and enzootic nasal tumor virus (ENTV) are two closely related oncogenic retroviruses that share the same cellular receptor yet exhibit distinct fusogenicity and infectivity. Here, we find that the low fusogenicity of ENTV envelope protein (Env) is not because of receptor binding, but lies in its intrinsic insensitivity to receptor-mediated triggering for fusion at low pH. Distinct from JSRV, shedding of ENTV surface (SU) subunit into culture medium was not enhanced by a soluble form of receptor, Hyal2 (sHyal2), and sHyal2 was unable to effectively inactivate the ENTV pseudovirions. Remarkably, replacing either of the two amino acid residues, N191 or S195, located in the ENTV SU with the corresponding JSRV residues, H191 or G195, markedly increased the Env-mediated membrane fusion activity and infection. Reciprocal amino acid substitutions also partly switched the sensitivities of ENTV and JSRV pseudovirions to sHyal2-mediated SU shedding and inactivation. While N191 is responsible for an extra N-linked glycosylation of ENTV SU relative to that of JSRV, S195 possibly forms a hydrogen bond with a surrounding amino acid residue. Molecular modeling of the pre-fusion structure of JSRV Env predicts that the segment of SU that contains H191 to G195 contacts the fusion peptide and suggests that the H191N and G195S changes seen in ENTV may stabilize its pre-fusion structure against receptor priming and therefore modulate fusion activation by Hyal2. In summary, our study reveals critical determinants in the SU subunits of JSRV and ENTV Env proteins that likely regulate their local structures and thereby differential receptor-mediated fusion activation at low pH, and these findings explain, at least in part, their distinct viral infectivity.
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Affiliation(s)
- Marceline Côté
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada H3A 2B4
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Jaagsiekte sheep retrovirus and enzootic nasal tumor virus promoters drive gene expression in all airway epithelial cells of mice but only induce tumors in the alveolar region of the lungs. J Virol 2011; 85:7535-45. [PMID: 21593165 DOI: 10.1128/jvi.00400-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Jaagsiekte sheep retrovirus (JSRV) induces tumors in the distal airways of sheep and goats, while the closely related enzootic nasal tumor virus type 1 (ENTV-1) and ENTV-2 induce tumors in the nasal epithelium of sheep and goats, respectively. When expressed using a strong Rous sarcoma virus promoter, the envelope proteins of these viruses induce tumors in the respiratory tract of mice, but only in the distal airway. To examine the role of the retroviral long terminal repeat (LTR) promoters in determining tissue tropism, adeno-associated virus (AAV) vectors expressing alkaline phosphatase under the control of the JSRV, ENTV-1, or ENTV-2 LTRs were generated and administered to mice. The JSRV LTR was active in all airway epithelial cells, while the ENTV LTRs were active in the nasal epithelium and alveolar type II cells but poorly active in tracheal and bronchial epithelial cells. When vectors were administered systemically, the ENTV-1 and -2 LTRs were inactive in major organs examined, whereas the JSRV showed high-level activity in the liver. When a putative transcriptional enhancer from the 3' end of the env gene was inserted upstream of the JSRV and ENTV-1 LTRs in the AAV vectors, a dramatic increase in transgene expression was observed. However, intranasal administration of AAV vectors containing any combination of ENTV or JSRV LTRs and Env proteins induced tumors only in the lower airway. Our results indicate that mice do not provide an adequate model for nasal tumor induction by ENTV despite our ability to express genes in the nasal epithelium.
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Jaagsiekte sheep retrovirus biology and oncogenesis. Viruses 2010; 2:2618-48. [PMID: 21994634 PMCID: PMC3185594 DOI: 10.3390/v2122618] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 11/22/2010] [Accepted: 11/23/2010] [Indexed: 11/19/2022] Open
Abstract
Jaagsiekte sheep retrovirus (JSRV) is the causative agent of a lung cancer in sheep known as ovine pulmonary adenocarcinoma (OPA). The disease has been identified around the world in several breeds of sheep and goats, and JSRV infection typically has a serious impact on affected flocks. In addition, studies on OPA are an excellent model for human lung carcinogenesis. A unique feature of JSRV is that its envelope (Env) protein functions as an oncogene. The JSRV Env-induced transformation or oncogenesis has been studied in a variety of cell systems and in animal models. Moreover, JSRV studies have provided insights into retroviral genomic RNA export/expression mechanisms. JSRV encodes a trans-acting factor (Rej) within the env gene necessary for the synthesis of Gag protein from unspliced viral RNA. This review summarizes research pertaining to JSRV-induced pathogenesis, Env transformation, and other aspects of JSRV biology.
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Griffiths D, Martineau H, Cousens C. Pathology and Pathogenesis of Ovine Pulmonary Adenocarcinoma. J Comp Pathol 2010; 142:260-83. [DOI: 10.1016/j.jcpa.2009.12.013] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 11/28/2009] [Accepted: 12/29/2009] [Indexed: 11/30/2022]
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[Receptors for animal retroviruses]. Uirusu 2010; 59:223-42. [PMID: 20218331 DOI: 10.2222/jsv.59.223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Diseases caused by animal retroviruses have been recognized since 19th century in veterinary field. Most livestock and companion animals have own retroviruses. To disclose the receptors for these retroviruses will be useful for understanding retroviral pathogenesis, developments of anti-retroviral drugs and vectors for human and animal gene therapies. Of retroviruses in veterinary field, receptors for the following viruses have been identified; equine infectious anemia virus, feline immunodeficiency virus, feline leukemia virus subgroups A, B, C, and T, Jaagsiekte sheep retrovirus, enzootic nasal tumor virus, avian leukosis virus subgroups A, B, C, D, E, and J, reticuloendotheliosis virus, RD-114 virus (a feline endogenous retrovirus), and porcine endogenous retrovirus subgroup A. Primate lentiviruses require two molecules (CD4 and chemokine receptors such as CXCR4) as receptors. Likewise, feline immunodeficiency virus also requires two molecules, i.e., CD134 (an activation marker of CD4 T cells) and CXCR4 in infection. Gammaretroviruses utilize multi-spanning transmembrane proteins, most of which are transporters of amino acids, vitamins and inorganic ions. Betaretroviruses and alpharetroviruses utilize transmembrane and/or GPI-anchored proteins as receptors. In this review, I overviewed receptors for animal retroviruses in veterinary field.
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The prostate cancer-associated human retrovirus XMRV lacks direct transforming activity but can induce low rates of transformation in cultured cells. J Virol 2009; 84:1874-80. [PMID: 20007266 DOI: 10.1128/jvi.01941-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The human retrovirus XMRV (xenotropic murine leukemia virus-related virus) is associated with prostate cancer, but a causal relationship has not been established. Here, we have used cultured fibroblast and epithelial cell lines to test the hypothesis that XMRV might have direct transforming activity but found only rare transformation events, suggestive of indirect transformation, even when the target cells expressed the human Xpr1 cell entry receptor for XMRV. Characterization of cells from three transformed foci showed that all were infected with and produced XMRV, and one produced a highly active transforming virus, presumably generated by recombination between XMRV and host cell nucleic acids. Given the sequence similarity of XMRV to mink cell focus-forming (MCF) viruses and the enhanced leukemogenic activity of the latter, we tested XMRV for related MCF-like cytopathic activities in cultured mink cells but found none. These results indicate that XMRV has no direct transforming activity but can activate endogenous oncogenes, resulting in cell transformation. As part of these experiments, we show that XMRV can infect and be produced at a high titer from human HT-1080 fibrosarcoma cells that express TRIM5alpha (Ref1), showing that XMRV is resistant to TRIM5alpha restriction. In addition, XMRV poorly infects NIH 3T3 cells expressing human Xpr1 but relatively efficiently infects BALB 3T3 cells expressing human Xpr1, showing that XMRV is a B-tropic virus and that its infectivity is regulated by the Fv1 mouse locus.
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Jaagsiekte sheep retrovirus encodes a regulatory factor, Rej, required for synthesis of Gag protein. J Virol 2009; 83:12483-98. [PMID: 19776124 DOI: 10.1128/jvi.01747-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Retroviruses express Gag and Pol proteins by translation of unspliced genome-length viral RNA. For some retroviruses, transport of unspliced viral RNA to the cytoplasm is mediated by small regulatory proteins such as human immunodeficiency virus Rev, while other retroviruses contain constitutive transport elements in their RNAs that allow transport without splicing. In this study, we found that the betaretrovirus Jaagsiekte sheep retrovirus (JSRV) encodes within the env gene a trans-acting factor (Rej) necessary for the synthesis of Gag protein from unspliced viral RNA. Deletion of env sequences from a JSRV proviral expression plasmid (pTN3) abolished its ability to produce Gag polyprotein in transfected 293T cells, and Gag synthesis could be restored by cotransfection of an env expression plasmid (DeltaGP). Deletion analysis localized the complementing activity (Rej) to the putative Env signal peptide, and a signal peptide expression construct showed Rej activity. Two other betaretroviruses, mouse mammary tumor virus (MMTV) and human endogenous retrovirus type K, encode analogous factors (Rem and Rec, respectively) that are encoded from doubly spliced env mRNAs. Reverse transcriptase-PCR cloning and sequencing identified alternate internal splicing events in the 5' end of JSRV env that could signify analogous doubly spliced Rej mRNAs, and cDNA clones expressing two of them also showed Rej activity. The predicted Rej proteins contain motifs similar to those found in MMTV Rem and other analogous retroviral regulatory proteins. Interestingly, in most cell lines, JSRV expression plasmids with Rej deleted showed normal transport of unspliced JSRV RNA to the cytoplasm; however, in 293T cells Rej modestly enhanced export of unspliced viral RNA (2.8-fold). Metabolic labeling experiments with [(35)S]methionine indicated that JSRV Rej is required for the synthesis of viral Gag polyprotein. Thus, in most cell lines, the predominant function of Rej is to facilitate translation of unspliced viral mRNA.
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Maeda N, Fan H, Yoshikai Y. Oncogenesis by retroviruses: old and new paradigms. Rev Med Virol 2008; 18:387-405. [PMID: 18729235 DOI: 10.1002/rmv.592] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Retroviruses are associated with a variety of diseases including an array of malignancies, immunodeficiencies and neurological disorders. In particular, studies of oncogenic retroviruses established fundamental principles of modern molecular cancer biology. Studies of avian Rous sarcoma virus (RSV) led to the discovery of the viral oncogene src, and this was followed by the discovery of other viral oncogenes in retroviruses of mammals including rodents, cats, monkeys and so forth. Studies of the viral oncogenes in turn led to the discovery of cellular proto-oncogenes in the host genome; cellular oncogenes have been shown to be activated in a variety of human cancers, including those with no viral involvement. Oncogenic animal retroviruses can be divided into two groups based on their mechanisms of tumourigenesis, acute transforming retroviruses and nonacute retroviruses. Acute transforming retroviruses are typically replication defective and they induce tumours rapidly due to expression of their viral oncogenes. Nonacute retroviruses are replication competent and they induce tumours with longer latencies, by activating cellular proto-oncogenes in the tumour cells; this results from insertion of proviral DNA in the vicinity of the activated proto-oncogene. More recently, human T-cell leukaemia virus type I (HTLV-I) was discovered as an etiological agent of human cancer (adult T-cell leukaemia [ATL]); this virus also encodes regulatory genes some of which are important for its oncogenic potential. Most recently, the retroviral structural protein Envelope (Env) has been shown to be directly involved in oncogenic transformation for certain retroviruses. Env-induced transformation is a new paradigm for retroviral oncogenesis. In this review, we will summarise research on retrovirus oncogenic transformation over the past 100 years since the first published report of an oncogenic virus with particular attention to Env-induced transformation.
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Affiliation(s)
- Naoyoshi Maeda
- Division of Host Defense, Research Center for Prevention of Infectious Diseases, Medical Institute of Bioregulation, Kyushu University, Higashi-ku, Fukuoka, Japan.
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Enzootic nasal tumor virus envelope requires a very acidic pH for fusion activation and infection. J Virol 2008; 82:9023-34. [PMID: 18632865 DOI: 10.1128/jvi.00648-08] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Enzootic nasal tumor virus (ENTV) is a close relative of jaagsiekte sheep retrovirus (JSRV), and the two viruses use the same receptor, hyaluronidase 2 (Hyal2), for cell entry. We report here that, unlike the JSRV envelope (Env) protein, the ENTV Env protein does not induce cell fusion at pHs of 5.0 and above but requires a much lower pH (4.0 to 4.5) for fusion to occur. The entry of ENTV Env pseudovirions was substantially inhibited by bafilomycin A1 (BafA1) but was surprisingly enhanced by lysosomotropic agents and lysosomal protease inhibitors following a 4- to 6-h treatment period; of note, prolonged treatment with BafA1 or ammonium chloride completely blocked ENTV entry. Unlike typical pH-dependent viruses, ENTV Env pseudovirions were virtually resistant to inactivation at a low pH (4.5 or 5.0). Using chimeras formed from ENTV and JSRV Env proteins, we demonstrated that the transmembrane (TM) subunit of ENTV Env is primarily responsible for its unusually low pH requirement for fusion but found that the surface (SU) subunit of ENTV Env also critically influences its relatively low and pH-dependent fusion activity. Furthermore, the poor infectivity of ENTV pseudovirions in human cells was significantly improved by either replacing the SU subunit of ENTV Env with that of JSRV Env or overexpressing the functional Hyal2 receptor in target cells, suggesting that ENTV SU-Hyal2 interaction is likely to be the limiting step for viral infectivity. Collectively, our data reveal that the fusogenicity of ENTV Env is intrinsically lower than that of JSRV Env and that ENTV requires a more acidic pH for fusion, which may occur in an intracellular compartment(s) distinct from that used by JSRV.
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Miller AD. Hyaluronidase 2 and its intriguing role as a cell-entry receptor for oncogenic sheep retroviruses. Semin Cancer Biol 2008; 18:296-301. [PMID: 18485731 DOI: 10.1016/j.semcancer.2008.03.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Accepted: 03/19/2008] [Indexed: 10/22/2022]
Abstract
Jaagsiekte sheep retrovirus (JSRV) causes lung adenocarcinoma in sheep and goats, while the closely related enzootic nasal tumor virus (ENTV) causes nasal tumors in the same species. The envelope (Env) protein from either virus can transform fibroblasts and epithelial cells in culture, indicating that the Env proteins are responsible for tumorigenesis. However, the primary function of retroviral Env proteins is to mediate virus entry into cells by interacting with specific cell-surface receptors, suggesting that the virus receptor might be a key player in transformation as well. Thus, identification of Hyaluronidase-2 (Hyal2) as the cell-entry receptor for both JSRV and ENTV suggested a role for Hyal2 in oncogenesis. Furthermore, Hyal2 is located in a key lung cancer tumor suppressor locus on chromosome 3p21.3, suggesting that Hyal2 might have a tumor suppressor activity that was disrupted by Env thereby leading to tumorigenesis. However, recent experiments showing that expression of the JSRV or ENTV Env protein in mouse lung can induce lung tumors, even though the viral Env proteins cannot bind to or utilize mouse Hyal2 as a receptor for virus entry into cells, indicate that Hyal2 plays no role in cancer induction by these retroviruses. Hyal2 remains an enigmatic member of the hyaluronidase family given its very low hyaluronidase activity in purified form or when expressed in cultured cells, suggesting that it may have evolved to perform some other as yet unknown function.
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Affiliation(s)
- A Dusty Miller
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA 98109-1024, USA.
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[New molecular mechanisms of virus-mediated carcinogenesis: oncogenic transformation of cells by retroviral structural protein Envelope]. Uirusu 2008; 57:159-70. [PMID: 18357754 DOI: 10.2222/jsv.57.159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
RNA tumor viruses as classified in Retroviruses have been isolated and identified to induce tumors in a variety of animals including chickens, mice, and rats, or even in human in the last 100 years, since the first one has been reported in 1908. The RNA tumor viruses have been historically classified into two groups, acute transforming RNA tumor viruses and nonacute RNA tumor viruses. Acute transforming RNA tumor viruses are basically replication-defective and rapidly induce tumors by expressing the viral oncogenes captured from cellular genome in host cells. The first oncogene derived from Rous sarcoma virus was the src non-receptor tyrosine kinase, which has been identified to play the significant roles for signal transduction. On the other hand, nonacute RNA tumor viruses, which consist of only gag, pro, pol, and env regions but do not carry oncogenes, are replication-competent and could activate the cellular proto-oncogenes by inserting the viral long terminal repeat close to the proto-oncogenes to induce tumors with a long incubation period, as is termed a promoter insertion. These molecular mechanisms have been thought to induce tumors. However, very recently several reports have described that the retroviral structural protein Envelope could directly induce tumors in vivo and transform cells in vitro. These are very unusual examples of native retroviral structural proteins with transformation potential. In this review we look back over the history of oncogenic retrovirus research and summarize recent progress for our understanding of the molecular mechanisms of oncogenic transformation by retrovirus Envelope proteins.
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Côté M, Zheng YM, Albritton LM, Liu SL. Fusogenicity of Jaagsiekte sheep retrovirus envelope protein is dependent on low pH and is enhanced by cytoplasmic tail truncations. J Virol 2008; 82:2543-54. [PMID: 18094165 PMCID: PMC2258932 DOI: 10.1128/jvi.01852-07] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2007] [Accepted: 12/13/2007] [Indexed: 01/05/2023] Open
Abstract
Jaagsiekte sheep retrovirus (JSRV) envelope (Env) is an active oncogene responsible for neoplastic transformation in animals and cultured cells. In this study, we used syncytium induction and fluorescence-based cell fusion assays to investigate JSRV Env fusion and its modulation by the cytoplasmic tail (CT). We found that JSRV Env induced syncytia in cells overexpressing the receptor for JSRV and that a low pH was required for this process to occur. Fusion kinetics studies revealed that cell-cell fusion by JSRV Env at neutral pH was poor, taking up to a day, in sharp contrast to fusion at low pH, which peaked within 2 min following a low-pH trigger. Deletion of the C-terminal 7 or 16 amino acids of the JSRV Env CT had no or little effect on fusion, yet additional truncation toward the membrane-spanning domain, resulting in mutants retaining as little as 1 amino acid of the CT, led to progressively increased syncytium formation at neutral pH that was further enhanced by low-pH treatment. Notably, the severely truncated mutants showed elevated levels of surface subunits in culture medium, suggesting that the CT truncations resulted in conformational changes in the ectodomain of Env that impaired surface subunit associations. Taken together, this study reveals for the first time that the fusion activity of the JSRV Env protein is dependent on a low pH and is modulated by the CT, whose truncation overcomes, at least partially, the low-pH requirement for fusion and enhances Env fusion activity and kinetics.
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Affiliation(s)
- Marceline Côté
- McGill University, Department of Microbiology and Immunology, 3775 University St., Montreal, QC H3A 2B4, Canada.
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Arnaud F, Caporale M, Varela M, Biek R, Chessa B, Alberti A, Golder M, Mura M, Zhang YP, Yu L, Pereira F, DeMartini JC, Leymaster K, Spencer TE, Palmarini M. A paradigm for virus-host coevolution: sequential counter-adaptations between endogenous and exogenous retroviruses. PLoS Pathog 2008; 3:e170. [PMID: 17997604 PMCID: PMC2065879 DOI: 10.1371/journal.ppat.0030170] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Accepted: 09/26/2007] [Indexed: 11/18/2022] Open
Abstract
Endogenous retroviruses (ERVs) are remnants of ancient retroviral infections of the host germline transmitted vertically from generation to generation. It is hypothesized that some ERVs are used by the host as restriction factors to block the infection of pathogenic retroviruses. Indeed, some ERVs efficiently interfere with the replication of related exogenous retroviruses. However, data suggesting that these mechanisms have influenced the coevolution of endogenous and/or exogenous retroviruses and their hosts have been more difficult to obtain. Sheep are an interesting model system to study retrovirus-host coevolution because of the coexistence in this animal species of two exogenous (i.e., horizontally transmitted) oncogenic retroviruses, Jaagsiekte sheep retrovirus and Enzootic nasal tumor virus, with highly related and biologically active endogenous retroviruses (enJSRVs). Here, we isolated and characterized the evolutionary history and molecular virology of 27 enJSRV proviruses. enJSRVs have been integrating in the host genome for the last 5–7 million y. Two enJSRV proviruses (enJS56A1 and enJSRV-20), which entered the host genome within the last 3 million y (before and during speciation within the genus Ovis), acquired in two temporally distinct events a defective Gag polyprotein resulting in a transdominant phenotype able to block late replication steps of related exogenous retroviruses. Both transdominant proviruses became fixed in the host genome before or around sheep domestication (∼ 9,000 y ago). Interestingly, a provirus escaping the transdominant enJSRVs has emerged very recently, most likely within the last 200 y. Thus, we determined sequentially distinct events during evolution that are indicative of an evolutionary antagonism between endogenous and exogenous retroviruses. This study strongly suggests that endogenization and selection of ERVs acting as restriction factors is a mechanism used by the host to fight retroviral infections. The genome of all vertebrates is heavily colonized by “endogenous” retroviruses (ERVs). ERVs derive from retrovirus infections of the germ cells of the host during evolution, leading to permanent integration of the viral genome into the host DNA. Because ERVs are integrated in the host genome, they are transmitted to subsequent generations like any other host gene. The function of endogenous retroviruses is not completely clear, but some ERVs can block the replication cycle of horizontally transmitted “exogenous” pathogenic retroviruses. These observations lead to the hypothesis that ERVs have protected the host during evolution against incoming pathogenic retroviruses. Here, by characterizing the evolutionary history and molecular virology of a particular group of endogenous betaretroviruses of sheep (enJSRVs) we show a fascinating series of events unveiling the endless struggle between host and retroviruses. In particular, we discovered that: (i) two enJSRV loci that entered the host genome before speciation within the genus Ovis (∼ 3 million y ago) acquired, after their integration, a mutated defective viral protein capable of blocking exogenous related retroviruses; (ii) both these transdominant enJSRV loci became fixed in the host genome before or around sheep domestication (∼ 10,000 y ago); (iii) the invasion of the sheep genome by ERVs of the JSRV/enJSRVs group is still in progress; and (iv) new viruses have recently emerged (less than 200 y ago) that can escape the transdominant enJSRV loci. This study strongly suggests that endogenization and selection of ERVs acting as restriction factors is a mechanism used by the host to fight retroviral infections.
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Affiliation(s)
- Frederick Arnaud
- Institute of Comparative Medicine, University of Glasgow Veterinary School, Glasgow, Scotland
| | - Marco Caporale
- Institute of Comparative Medicine, University of Glasgow Veterinary School, Glasgow, Scotland
| | - Mariana Varela
- Institute of Comparative Medicine, University of Glasgow Veterinary School, Glasgow, Scotland
| | - Roman Biek
- Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, Scotland
| | - Bernardo Chessa
- Sezione di Malattie Infettive del Dipartimento di Patologia e Clinica Veterinaria, University of Sassari, Sassari, Italy
| | - Alberto Alberti
- Sezione di Malattie Infettive del Dipartimento di Patologia e Clinica Veterinaria, University of Sassari, Sassari, Italy
| | - Matthew Golder
- Institute of Comparative Medicine, University of Glasgow Veterinary School, Glasgow, Scotland
| | - Manuela Mura
- Institute of Comparative Medicine, University of Glasgow Veterinary School, Glasgow, Scotland
| | - Ya-ping Zhang
- State Key Laboratory of Genetic Resources, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - Li Yu
- Laboratory for Conservation and Utilization of Bioresources, Yunnan University, Kunming, China
| | - Filipe Pereira
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal
- Faculdade de Ciências, Universidade do Porto, Porto, Portugal
| | - James C DeMartini
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Kreg Leymaster
- United States Meat Animal Research Center, Clay Center, Nebraska, United States of America
| | - Thomas E Spencer
- Center for Animal Biotechnology and Genomics, Department of Animal Science, Texas A&M University, College Station, Texas, United States of America
| | - Massimo Palmarini
- Institute of Comparative Medicine, University of Glasgow Veterinary School, Glasgow, Scotland
- * To whom correspondence should be addressed. E-mail:
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Maeda N, Fan H. Signal transduction pathways utilized by enzootic nasal tumor virus (ENTV-1) envelope protein in transformation of rat epithelial cells resemble those used by jaagsiekte sheep retrovirus. Virus Genes 2008; 36:147-55. [DOI: 10.1007/s11262-007-0193-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Accepted: 12/20/2007] [Indexed: 11/21/2022]
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McGee-Estrada K, Fan H. Comparison of LTR enhancer elements in sheep betaretroviruses: insights into the basis for tissue-specific expression. Virus Genes 2007; 35:303-12. [PMID: 17268841 DOI: 10.1007/s11262-007-0079-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Accepted: 01/10/2007] [Indexed: 11/27/2022]
Abstract
Jaagsiekte sheep retrovirus (JSRV), enzootic nasal tumor virus (ENTV), and endogenous sheep retroviruses (ESRVs) are highly related sheep betaretroviruses that display different expression profiles in vivo. JSRV and ENTV are expressed in lungs and nasal adenocarcinomas, respectively, while ESRVs are primarily expressed in the reproductive tract of ewes. Evidence suggests that the cell tropism of JSRV, ENTV, and ESRVs is due to the transcriptional specificity of the LTRs. We have previously found several enhancer elements in the JSRV LTR that are important for lung-specific expression, including binding sites for the lung-specific transcription factor HNF-3beta, as well as binding sites for the ubiquitously expressed transcription factors C/EBP and NF-I. In this study, we have aligned the U3 regions of JSRV, ENTV, and several ESRVs in order to compare the transcriptional enhancer elements of JSRV that are conserved or absent in ESRV and ENTV. All three JSRV U3 sequences examined contain two conserved HNF-3 binding sites, while the ENTV and ESRV U3 regions are not predicted to bind this transcription factor. In addition, the C/EBP binding site is interrupted in the ESRV LTRs, but conserved in the ENTV LTRs. Some enhancer elements are conserved between JSRV and ENTV, but a reporter vector carrying the ENTV-1 LTR showed less activity than a JSRV LTR-driven reporter vector in a lung epithelial cell line. These studies support the importance of LTR enhancer elements in the respective tissue specificities of these exogenous and endogenous betaretroviruses.
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Leroux C, Girard N, Cottin V, Greenland T, Mornex JF, Archer F. Jaagsiekte Sheep Retrovirus (JSRV): from virus to lung cancer in sheep. Vet Res 2007; 38:211-28. [PMID: 17257570 DOI: 10.1051/vetres:2006060] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Accepted: 11/23/2006] [Indexed: 01/16/2023] Open
Abstract
Jaagsiekte Sheep Retrovirus (JSRV) is a betaretrovirus infecting sheep. This virus is responsible for a pulmonary adenocarcinoma, by transformation of epithelial cells from the bronchioli and alveoli. This animal cancer is similar to human bronchioloalveolar cancer (BAC), a specific form of human lung cancer for which a viral aetiology has not yet been identified. JSRV interacts with target cells through the membrane receptor Hyal2. The JSRV genome is simple and contains no recognised oncogene. It is now well established that the viral envelope protein is oncogenic by itself, via the cytoplasmic domain of the transmembrane glycoprotein and some domains of the surface glycoprotein. Activation of the PI3K/Akt and MAPK pathways participates in the envelope-induced transformation. Tumour development is associated with telomerase activation. This review will focus on the induction of cancer by JSRV.
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Affiliation(s)
- Caroline Leroux
- Université de Lyon 1, INRA, UMR754, Ecole Nationale Vétérinaire de Lyon, IFR 128, F-69007, Lyon, France.
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Miller AD, Vigdorovich V, Strong RK, Fernandes RJ, Lerman MI. Hyal2, where are you? Osteoarthritis Cartilage 2006; 14:1315-7. [PMID: 16990026 DOI: 10.1016/j.joca.2006.08.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Indexed: 02/02/2023]
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Wootton SK, Halbert CL, Miller AD. Envelope proteins of Jaagsiekte sheep retrovirus and enzootic nasal tumor virus induce similar bronchioalveolar tumors in lungs of mice. J Virol 2006; 80:9322-5. [PMID: 16940543 PMCID: PMC1563922 DOI: 10.1128/jvi.00865-06] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Jaagsiekte sheep retrovirus (JSRV) induces bronchioalveolar tumors in sheep and goats. Expression of the JSRV envelope (Env) protein in mouse airway epithelial cells induces similar tumors, indicating that Env expression is sufficient for tissue-specific tumor formation. Enzootic nasal tumor virus (ENTV) is related to JSRV but induces tumors in the nasal epithelium of sheep and goats. Here we found that ENTV Env can also induce tumors in mice but, unexpectedly, with a phenotype identical to that of tumors induced by the JSRV Env, indicating that factors other than Env mediate the tissue specificity of tumor induction by ENTV.
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Affiliation(s)
- Sarah K Wootton
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Room C2-105, Seattle, WA 98109-1024, USA
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Abstract
Retroviruses have played profound roles in our understanding of the genetic and molecular basis of cancer. Jaagsiekte sheep retrovirus (JSRV) is a simple retrovirus that causes contagious lung tumors in sheep, known as ovine pulmonary adenocarcinoma (OPA). Intriguingly, OPA resembles pulmonary adenocarcinoma in humans, and may provide a model for this frequent human cancer. Distinct from the classical mechanisms of retroviral oncogenesis by insertional activation of or virus capture of host oncogenes, the native envelope (Env) structural protein of JSRV is itself the active oncogene. A major pathway for Env transformation involves interaction of the Env cytoplasmic tail with as yet unidentified cellular adaptor(s), leading to the activation of PI3K/Akt and MAPK signaling cascades. Another potential mechanism involves the cell-entry receptor for JSRV, Hyaluronidase 2 (Hyal2), and the RON receptor tyrosine kinase, but the exact roles of these proteins in JSRV Env transformation remain to be better understood. Recently, a mouse model of lung cancer induced by JSRV Env has been developed, and the tumors in mice resemble those seen in sheep infected with JSRV and in humans. In this review, we summarize recent progress in our understanding the molecular mechanisms of oncogenic transformation by JSRV Env protein, and discuss the relevance to human lung cancer.
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Affiliation(s)
- S-L Liu
- Department of Microbiology and Immunology, McGill University, Montreal, Canada.
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De Las Heras M, Ortín A, Benito A, Summers C, Ferrer LM, Sharp JM. In-situ Demonstration of Mitogen-activated Protein Kinase Erk 1/2 Signalling Pathway in Contagious Respiratory Tumours of Sheep and Goats. J Comp Pathol 2006; 135:1-10. [PMID: 16814801 DOI: 10.1016/j.jcpa.2006.02.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Accepted: 02/02/2006] [Indexed: 11/19/2022]
Abstract
Ovine pulmonary adenocarcinoma (OPA) and enzootic nasal adenocarcinoma (ENA) are two contagious neoplastic diseases of secretory epithelial cells in the respiratory system of sheep and goats. Jaagsiekte sheep retrovirus (JSRV) is the aetiological agent of OPA, and enzootic nasal tumour virus (ENTV) is associated with ENA. The genomes of these retroviruses do not contain known oncogenes but products of the env gene are important in the generation of transforming stimuli. However, the cell signalling pathways activated in vivo are not completely understood. This study was based on the use of activation stage antibodies specifically detecting proteins of the extracellular signal regulated kinase Erk 1/2 cell signalling pathway and transcription factors. Tissue sections were collected from four natural cases of OPA, four experimentally induced OPA tumours, four ENA tumours in sheep, four ENA tumours in goats, two normal sheep lungs and two lungs with chronic inflammation. Routine immunohistochemical procedures with phosphorylation stage-specific antibodies were carried out. Representative proteins of the Erk1/2 pathway (Raf-1, Mek1/2 and p44/42MAPK) were activated in natural cases of OPA and ENA in sheep and goats and also in experimentally induced OPA. Transcription factors 90Rsk and Elk-1 were activated in OPA and ENA tumours. However, c-Myc was activated only in OPA tumours. In contagious respiratory neoplasms of sheep and goats the Erk1/2 pathway appears to be important for the in-vivo generation of the transforming stimuli.
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Affiliation(s)
- M De Las Heras
- Departamento de Patología Animal, Facultad de Veterinaria, Universidad de Zaragoza, C/ Miguel Servet 177, 50013 Zaragoza, Spain.
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Duh FM, Dirks C, Lerman MI, Miller AD. Amino acid residues that are important for Hyal2 function as a receptor for jaagsiekte sheep retrovirus. Retrovirology 2005; 2:59. [PMID: 16191204 PMCID: PMC1262777 DOI: 10.1186/1742-4690-2-59] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Accepted: 09/28/2005] [Indexed: 02/06/2023] Open
Abstract
Background Infection by jaagsiekte sheep retrovirus (JSRV) and by enzootic nasal tumor virus (ENTV) depends on cell-surface expression of the virus entry receptor, hyaluronidase 2 (Hyal2). Human Hyal2 binds the envelope (Env) proteins of these viruses and is functional as a receptor, but Hyal2 from mice does not bind Env nor does it mediate entry of either virus. Here we have explored the amino acid determinants that account for the difference in receptor function. Results Analysis of human-mouse Hyal2 chimeric proteins showed that amino acid differences responsible for the difference in Hyal2 receptor activity were localized to the central third of Hyal2. Human Hyal2 mutants containing single or double amino acid replacements with the respective mouse amino acids were generated across this region and were assayed for activity. None of the single or double mutation reduced the receptor activity of human Hyal2 by more than 10-fold, whereas mouse Hyal2 activity is reduced 1,000-fold from that of human Hyal2. While the 3-dimensional structures of mammalian Hyal2 proteins are unknown, bee venom hyaluronidase shows significant amino acid similarity to human and mouse Hyal2 and its structure has been determined. Many mutations having the largest negative effects on human Hyal2 function mapped to a small region of the bee venom hyaluronidase close to but not overlapping the active site of the enzyme, suggesting that this site represents the binding site for Env. Analysis of synonymous and non-synonymous nucleotide substitutions in the coding sequences of multiple mammalian Hyal2 proteins shows that the proteins are undergoing strong selection for amino acid conservation. We found no evidence for positive selection of amino acid changes that might reflect evolution of mammalian hosts to resist JSRV or ENTV infection. Conclusion These results show that the greatly reduced receptor activity of mouse Hyal2 in comparison to that of human Hyal2 is determined by multiple amino acid changes acting in concert. In particular, no one amino acid change blocks infection. However, the most important amino acids map to a small patch on a predicted 3-dimensional Hyal2 structure, which may represent the binding site for Env.
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Affiliation(s)
- Fuh-Mei Duh
- Basic Research Program, SAIC-Frederick, National Cancer Institute at Frederick, Frederick, Maryland 21702, USA
- Laboratory of Immunobiology, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland 21702, USA
| | - Clarissa Dirks
- Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
- Current address: University of Washington, Seattle, Washington 98195, USA
| | - Michael I Lerman
- Laboratory of Immunobiology, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland 21702, USA
| | - A Dusty Miller
- Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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Dunlap KA, Palmarini M, Adelson DL, Spencer TE. Sheep Endogenous Betaretroviruses (enJSRVs) and the Hyaluronidase 2 (HYAL2) Receptor in the Ovine Uterus and Conceptus. Biol Reprod 2005; 73:271-9. [PMID: 15788753 DOI: 10.1095/biolreprod.105.039776] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The ovine genome contains approximately 20 copies of endogenous betaretroviruses (enJSRVs) that are highly related to two exogenous oncogenic viruses, Jaagsiekte sheep retrovirus (JSRV) and Enzootic nasal tumor virus. The cellular receptor for both JSRV and the enJSRVs is hyaluronidase 2 (HYAL2). In this study, we assessed expression of enJSRVs envelope (env) and HYAL2 mRNAs in the ovine uterus and conceptus (embryo/fetus and extraembryonic membranes) throughout gestation. By reverse transcription-polymerase chain reaction analyses, enJSRVs env were found to be expressed beginning in the Day 12 conceptus, whereas HYAL2 was expressed from Day 16. HYAL2 mRNA was detected throughout gestation in the placentome but not in the endometrium, whereas enJSRVs env expression was detected throughout gestation in endometrium and placentomes. The enJSRVs env mRNA was specifically expressed in the endometrial lumenal epithelium (LE) and glandular epithelium (GE) as well as the trophoblast giant binucleate cells (BNC) and multinucleated syncytia of the placenta. HYAL2 mRNA was only detected in the BNC and multinucleated syncytial plaques of the placentome. Partial sequencing of the transcriptionally active enJSRVs from sheep endometrium, placentomes, and placenta revealed expression of many enJSRV loci. Cloning of the expressed enJSRVs env mRNA from ovine uteroplacental tissues found sequences similar to the previously identified enJS5F16 and enJS56A1 gene with an intact open reading frame, although the polypeptides they encode were not studied. Collectively, results provide further support for our hypothesis that the enJSRVs Env have been beneficial to the host and are involved in protection of the uterus from viral infection and regulators of placental morphogenesis and function.
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Affiliation(s)
- Kathrin A Dunlap
- Center for Animal Biotechnology and Genomics, Department of Animal Science, Texas A&M University, College Station, Texas 77843-2471, USA
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Sinn PL, Burnight ER, Shen H, Fan H, McCray PB. Inclusion of Jaagsiekte sheep retrovirus proviral elements markedly increases lentivirus vector pseudotyping efficiency. Mol Ther 2005; 11:460-9. [PMID: 15727943 DOI: 10.1016/j.ymthe.2004.10.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2004] [Revised: 10/11/2004] [Accepted: 10/26/2004] [Indexed: 11/23/2022] Open
Abstract
Retroviral pseudotyping for gene transfer applications endeavors to alter vector tropism and maintain a suitable titer. We investigated the compatibility of the Jaagsiekte sheep retrovirus (JSRV) envelope glycoprotein with the feline immunodeficiency virus (FIV) vector. A construct consisting of the minimal JSRV env coding region expressed from a standard mammalian expression plasmid generated FIV vector titers of approximately 10(4) TU/ml following standard triple transfection, collection of supernatants, and concentration by centrifuge. Interestingly, retention of the native proviral 5' and 3' flanking regions surrounding the JSRV env resulted in exceptional titers of approximately 10(8) TU/ml following the same viral preparation. To discern the regions necessary to achieve this 10,000-fold increase in titer, additional constructs were designed and tested. Our results indicate that the enhanced vector titer correlates with an increase in steady-state levels of envelope RNA that results from a combination of RNA splicing and stability, leading to increased envelope protein production. Expression of four other glycoproteins in an expression plasmid retaining the enhancing elements from the JSRV proviral sequence increased FIV vector titers from 0- to 100-fold. These novel data demonstrate that optimization of the envelope expression construct can profoundly influence titers for lentivirus vectors.
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Affiliation(s)
- Patrick L Sinn
- Department of Pediatrics, Program in Gene Therapy, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
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Maeda N, Fu W, Ortin A, de las Heras M, Fan H. Roles of the Ras-MEK-mitogen-activated protein kinase and phosphatidylinositol 3-kinase-Akt-mTOR pathways in Jaagsiekte sheep retrovirus-induced transformation of rodent fibroblast and epithelial cell lines. J Virol 2005; 79:4440-50. [PMID: 15767444 PMCID: PMC1061532 DOI: 10.1128/jvi.79.7.4440-4450.2005] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Jaagsiekte sheep retrovirus (JSRV) is the causative agent of ovine pulmonary adenocarcinoma (OPA), a transmissible lung cancer of sheep. The virus can induce tumors rapidly, and we previously found that the JSRV envelope protein (Env) functions as an oncogene, because it can transform mammalian and avian fibroblast cell lines. (N. Maeda, Proc. Natl. Acad. Sci. USA 98:4449-4454, 2001). The molecular mechanisms of JSRV Env transformation are of considerable interest. Several reports suggested that the phosphatidylinositol 3-kinase/Akt pathway is important for transformation of mammalian fibroblasts but not for chicken fibroblasts. In this study, we found that Akt/mTOR is involved in JSRV transformation of mouse NIH 3T3 fibroblasts, because treatment with the mTOR inhibitor rapamycin reduced transformation. We also found that H/N-Ras inhibitor FTI-277 and MEK1/2 inhibitors PD98059 and U0126 strongly inhibited JSRV transformation of NIH 3T3 fibroblasts, suggesting that the H/N-Ras-MEK-mitogen-activated protein kinase (MAPK) p44/42 pathway is necessary for the transformation. In RK3E epithelial cells, the MEK1/2 inhibitors also eliminated transformation, but FTI-277 only partially inhibited transformation. It was noteworthy that p38 MAPK inhibitors enhanced JSRV transformation in both fibroblasts and epithelial cells. Treatment of transformed cells with p38 inhibitors both increased levels of phospho-MEK1/2 and phospho-p44/42 and induced rapid enhancement of the transformed phenotype. Immunohistochemical staining of tumor tissues from naturally and experimentally induced OPA and naturally occurring enzootic nasal adenocarcinoma revealed strong activation of MAPK p44/42 in all cases examined. However, p38 activation was not generally observed. These results indicate that signaling through two pathways (in particular, H/N-Ras-MEK-MAPK and, to a lesser extent, Akt-mTOR) is important for JSRV-induced transformation and that p38 MAPK has a negative regulatory effect on transformation, perhaps via MEK1/2 and p44/42.
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Affiliation(s)
- Naoyoshi Maeda
- Cancer Research Institute, University of California, Irvine, Irvine, CA 92697-3900, USA
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Sinn PL, Penisten AK, Burnight ER, Hickey MA, Williams G, McCoy DM, Mallampalli RK, McCray PB. Gene Transfer to Respiratory Epithelia with Lentivirus Pseudotyped with Jaagsiekte Sheep Retrovirus Envelope Glycoprotein. Hum Gene Ther 2005; 16:479-88. [PMID: 15871679 DOI: 10.1089/hum.2005.16.479] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A feline immunodeficiency virus (FIV)-based lentiviral vector was pseudotyped to identify envelope (env) glycoproteins that direct efficient gene transfer to pulmonary epithelia for the treatment or prevention of lung diseases. The envelope glycoprotein from the Jaagsiekte sheep retrovirus (JSRV) is a candidate under investigation. We utilized high titer FIV vector (>10(8) TU/ml) pseudotyped with the JSRV env glycoprotein (JSRVFIV) to study the transduction of polarized primary cultures of human airway epithelia and receptor/vector interactions. The reported receptor for JSRV, hyaluronidase 2 (HYAL2), is a GPI-linked protein. We expressed FLAG-tagged HYAL2 in polarized airway epithelia using an adenoviral vector and documented that the HYAL2 protein sorts predominantly to the apical surface. Of interest, the efficiency of gene transfer with apically applied JSRV-FIV was markedly less than FIV pseudotyped with VSV-G, even in Ad-HYAL2 complemented epithelia. The inefficient gene transfer with JSRV-FIV in HYAL2 complemented cells suggests that factors other than receptor abundance limit apical gene transfer efficiency with this envelope. JSRV-FIV transduced the distal lung epithelia of rabbits in vivo and transduced primary cultures of rabbit type II cells with 100-fold greater efficiency than primary cultures of rabbit tracheal cells. These data indicate that a lentivirus pseudotyped with the JSRV envelope glycoprotein transduces type II cells with greater efficiency than conducting airway epithelia and provides an example of glycoprotein-mediated cell-specific tropism within a tissue with a widely heterogeneous cell population.
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Affiliation(s)
- Patrick L Sinn
- Program in Gene Therapy, Department of Pediatrics, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
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Vigdorovich V, Strong RK, Miller AD. Expression and characterization of a soluble, active form of the jaagsiekte sheep retrovirus receptor, Hyal2. J Virol 2005; 79:79-86. [PMID: 15596803 PMCID: PMC538683 DOI: 10.1128/jvi.79.1.79-86.2005] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Retrovirus entry into cells is mediated by specific interactions between virus envelope glycoproteins and cell surface receptors. Many of these receptors contain multiple membrane-spanning regions, making their purification and study difficult. The jaagsiekte sheep retrovirus (JSRV) receptor, hyaluronidase 2 (Hyal2), is a glycosylphosphatidylinositol (GPI)-anchored molecule containing no peptide transmembrane regions, making it an attractive candidate for study of retrovirus entry. Further, the hyaluronidase activity reported for human Hyal2, combined with its broad expression pattern, may point to a critical function of Hyal2 in the turnover of hyaluronan, a major extracellular matrix component. Here we describe the properties of a soluble form of human Hyal2 (sHyal2) purified from a baculoviral expression system. sHyal2 is a 54-kDa monomer with weak hyaluronidase activity compared to that of the known hyaluronidase Spam1. In contrast to a previous report indicating that Hyal2 cleaved hyaluronan to a limit product of 20 kDa and was active only at acidic pH, we find that sHyal2 is capable of further degradation of hyaluronan and is active over a broad pH range, consistent with Hyal2 being active at the cell surface where it is normally localized. Interaction of sHyal2 with the JSRV envelope glycoprotein was analyzed by viral inhibition assays, showing >90% inhibition of transduction at 28 nM sHyal2, and by surface plasmon resonance, revealing a remarkably tight specific interaction with a dissociation constant (KD) of 32 +/- 1 pM. In contrast to results obtained with avian retroviruses, purified receptor was not capable of promoting transduction of cells that do not express the virus receptor.
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Affiliation(s)
- Vladimir Vigdorovich
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109-1024, USA
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Van Hoeven NS, Miller AD. Improved enzootic nasal tumor virus pseudotype packaging cell lines reveal virus entry requirements in addition to the primary receptor Hyal2. J Virol 2005; 79:87-94. [PMID: 15596804 PMCID: PMC538734 DOI: 10.1128/jvi.79.1.87-94.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2004] [Accepted: 08/26/2004] [Indexed: 11/20/2022] Open
Abstract
Enzootic nasal tumor virus (ENTV) and jaagsiekte sheep retrovirus (JSRV) are closely related retroviruses that cause epithelial cancers of the respiratory tract in sheep and goats. Both viruses use the glycosylphosphatidylinositol (GPI)-anchored cell surface protein hyaluronidase 2 (Hyal2) as a receptor for cell entry, and entry is mediated by the envelope (Env) proteins encoded by these viruses. Retroviral vectors bearing JSRV Env can transduce cells from a wide range of species, with the exception of rodent cells. Because of the low titer of vectors bearing ENTV Env, it has been difficult to determine the tropism of ENTV vectors, which appeared to transduce cells from sheep and humans only. Here we have developed high-titer ENTV packaging cells and confirm that ENTV has a restricted host range compared to that of JSRV. Most cells that are not transduced by JSRV or ENTV vectors can be made susceptible following expression of human Hyal2 on the cells. However, five rat cell lines from different rat strains and different tissues that were engineered to express human Hyal2 were still only poorly infected by ENTV vectors, even though the ENTV Env protein could bind well to human Hyal2 expressed on four of these cell lines. These results indicate the possibility of a coreceptor requirement for these viruses.
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Affiliation(s)
- Neal S Van Hoeven
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109-1024, USA
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Liu SL, Miller AD. Transformation of madin-darby canine kidney epithelial cells by sheep retrovirus envelope proteins. J Virol 2005; 79:927-33. [PMID: 15613321 PMCID: PMC538587 DOI: 10.1128/jvi.79.2.927-933.2005] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2004] [Accepted: 08/26/2004] [Indexed: 11/20/2022] Open
Abstract
Jaagsiekte sheep retrovirus (JSRV) and enzootic nasal tumor virus (ENTV) induce epithelial tumors in the airways of sheep and goats. In both of these simple retroviruses, the envelope (Env) protein is the active oncogene. Furthermore, JSRV Env can transform cultured cells by two distinct mechanisms. In rat and mouse fibroblasts, the cytoplasmic tail of JSRV Env is essential for transformation, which involves activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, and the virus receptor hyaluronidase 2 (Hyal2) is not involved. In contrast, in the BEAS-2B human bronchial epithelial cell line, transformation is mediated by JSRV Env binding to Hyal2 followed by Hyal2 degradation and activation of the receptor tyrosine kinase RON, the activity of which is normally suppressed by Hyal2. Here we show that JSRV and ENTV Env proteins can also transform Madin-Darby canine kidney (MDCK) epithelial cells, but by a mechanism similar to that observed in fibroblast cell lines. In particular, the cytoplasmic tail of Env is required for transformation, the PI3K/Akt pathway is activated, expression of RON (which is not normally expressed in MDCK cells) does not affect transformation, and canine Hyal2 appears uninvolved. These results show that the JSRV and ENTV Env proteins can transform epithelial cells besides BEAS-2B cells and argue against a model for Env transformation involving different pathways that are uniquely active in fibroblasts or epithelial cells.
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Affiliation(s)
- Shan-Lu Liu
- Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N., Room C2-105, Seattle, WA 98109-1024, USA
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