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Jaguva Vasudevan AA, Becker D, Luedde T, Gohlke H, Münk C. Foamy Viruses, Bet, and APOBEC3 Restriction. Viruses 2021; 13:504. [PMID: 33803830 PMCID: PMC8003144 DOI: 10.3390/v13030504] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/10/2021] [Accepted: 03/16/2021] [Indexed: 01/24/2023] Open
Abstract
Non-human primates (NHP) are an important source of viruses that can spillover to humans and, after adaptation, spread through the host population. Whereas HIV-1 and HTLV-1 emerged as retroviral pathogens in humans, a unique class of retroviruses called foamy viruses (FV) with zoonotic potential are occasionally detected in bushmeat hunters or zookeepers. Various FVs are endemic in numerous mammalian natural hosts, such as primates, felines, bovines, and equines, and other animals, but not in humans. They are apathogenic, and significant differences exist between the viral life cycles of FV and other retroviruses. Importantly, FVs replicate in the presence of many well-defined retroviral restriction factors such as TRIM5α, BST2 (Tetherin), MX2, and APOBEC3 (A3). While the interaction of A3s with HIV-1 is well studied, the escape mechanisms of FVs from restriction by A3 is much less explored. Here we review the current knowledge of FV biology, host restriction factors, and FV-host interactions with an emphasis on the consequences of FV regulatory protein Bet binding to A3s and outline crucial open questions for future studies.
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Affiliation(s)
- Ananda Ayyappan Jaguva Vasudevan
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany;
| | - Daniel Becker
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany; (D.B.); (H.G.)
| | - Tom Luedde
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany;
| | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany; (D.B.); (H.G.)
- John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre & Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Carsten Münk
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany;
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2
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Inhibitors of the interferon response increase the replication of gorilla simian foamy viruses. Virology 2019; 541:25-31. [PMID: 31826843 DOI: 10.1016/j.virol.2019.11.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 11/28/2019] [Accepted: 11/29/2019] [Indexed: 12/17/2022]
Abstract
Simian foamy viruses (SFVs) are complex retroviruses that are widespread throughout nonhuman primates. SFVs can also be transmitted to humans, mostly through bites. We previously observed that primary zoonotic gorilla SFV strains grow much more slowly than laboratory-adapted chimpanzee strains. Here, we tested the hypothesis that the growth of SFV is limited by interferon (IFN) using inhibitors of cellular pathways involved in the induction or action of type I IFN. Inhibitors of JAK1/2 (Ruxolitinib) and TBK-1 (BX795) led to a 2- to 4-fold higher percentage of cells infected with zoonotic gorilla SFVs but did not affect the replication of laboratory-adapted chimpanzee SFVs. IKK2 inhibitors (TPCA-1 and BMS345541) had no effect on any of the SFV strains. In conclusion, the addition of molecules that inhibit the type I IFN response to the culture medium can be used as a simple and efficient method to enhance the replication of zoonotic gorilla SFVs.
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Bergez M, Weber J, Riess M, Erdbeer A, Seifried J, Stanke N, Munz C, Hornung V, König R, Lindemann D. Insights into Innate Sensing of Prototype Foamy Viruses in Myeloid Cells. Viruses 2019; 11:v11121095. [PMID: 31779173 PMCID: PMC6950106 DOI: 10.3390/v11121095] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 11/21/2019] [Accepted: 11/22/2019] [Indexed: 01/18/2023] Open
Abstract
Foamy viruses (FVs) belong to the Spumaretrovirinae subfamily of retroviruses and are characterized by unique features in their replication strategy. This includes a reverse transcription (RTr) step of the packaged RNA genome late in replication, resulting in the release of particles with a fraction of them already containing an infectious viral DNA (vDNA) genome. Little is known about the immune responses against FVs in their hosts, which control infection and may be responsible for their apparent apathogenic nature. We studied the interaction of FVs with the innate immune system in myeloid cells, and characterized the viral pathogen-associated molecular patterns (PAMPs) and the cellular pattern recognition receptors and sensing pathways involved. Upon cytoplasmic access, full-length but not minimal vector genome containing FVs with active reverse transcriptase, induced an efficient innate immune response in various myeloid cells. It was dependent on cellular cGAS and STING and largely unaffected by RTr inhibition during viral entry. This suggests that RTr products, which are generated during FV morphogenesis in infected cells, and are therefore already present in FV particles taken up by immune cells, are the main PAMPs of FVs with full-length genomes sensed in a cGAS and STING-dependent manner by the innate immune system in host cells of the myeloid lineage.
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Affiliation(s)
- Maïwenn Bergez
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225 Langen, Germany; (M.B.); (M.R.); (J.S.)
| | - Jakob Weber
- Institute of Virology, Medical Faculty “Carl Gustav Carus”, Technische Universität Dresden, 01307 Dresden, Germany; (J.W.); (A.E.); (N.S.); (C.M.)
- CRTD/DFG-Center for Regenerative Therapies, Technische Universität Dresden, 01307 Dresden, Germany
| | - Maximilian Riess
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225 Langen, Germany; (M.B.); (M.R.); (J.S.)
| | - Alexander Erdbeer
- Institute of Virology, Medical Faculty “Carl Gustav Carus”, Technische Universität Dresden, 01307 Dresden, Germany; (J.W.); (A.E.); (N.S.); (C.M.)
- CRTD/DFG-Center for Regenerative Therapies, Technische Universität Dresden, 01307 Dresden, Germany
| | - Janna Seifried
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225 Langen, Germany; (M.B.); (M.R.); (J.S.)
| | - Nicole Stanke
- Institute of Virology, Medical Faculty “Carl Gustav Carus”, Technische Universität Dresden, 01307 Dresden, Germany; (J.W.); (A.E.); (N.S.); (C.M.)
- CRTD/DFG-Center for Regenerative Therapies, Technische Universität Dresden, 01307 Dresden, Germany
| | - Clara Munz
- Institute of Virology, Medical Faculty “Carl Gustav Carus”, Technische Universität Dresden, 01307 Dresden, Germany; (J.W.); (A.E.); (N.S.); (C.M.)
- CRTD/DFG-Center for Regenerative Therapies, Technische Universität Dresden, 01307 Dresden, Germany
| | - Veit Hornung
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, 81377 München, Germany;
| | - Renate König
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225 Langen, Germany; (M.B.); (M.R.); (J.S.)
- German Center for Infection Research (DZIF), 63225 Langen, Germany
- Immunity and Pathogenesis Program, SBP Medical Discovery Institute, La Jolla, CA 92037, USA
- Correspondence: (R.K.); (D.L.); Tel.: +49-6103-77-4019 (R.K.); +49-351-458-6210 (D.L.)
| | - Dirk Lindemann
- Institute of Virology, Medical Faculty “Carl Gustav Carus”, Technische Universität Dresden, 01307 Dresden, Germany; (J.W.); (A.E.); (N.S.); (C.M.)
- CRTD/DFG-Center for Regenerative Therapies, Technische Universität Dresden, 01307 Dresden, Germany
- Correspondence: (R.K.); (D.L.); Tel.: +49-6103-77-4019 (R.K.); +49-351-458-6210 (D.L.)
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Aiewsakun P, Simmonds P, Katzourakis A. The First Co-Opted Endogenous Foamy Viruses and the Evolutionary History of Reptilian Foamy Viruses. Viruses 2019; 11:v11070641. [PMID: 31336856 PMCID: PMC6669660 DOI: 10.3390/v11070641] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/01/2019] [Accepted: 07/04/2019] [Indexed: 12/17/2022] Open
Abstract
A recent study reported the discovery of an endogenous reptilian foamy virus (FV), termed ERV-Spuma-Spu, found in the genome of tuatara. Here, we report two novel reptilian foamy viruses also identified as endogenous FVs (EFVs) in the genomes of panther gecko (ERV-Spuma-Ppi) and Schlegel’s Japanese gecko (ERV-Spuma-Gja). Their presence indicates that FVs are capable of infecting reptiles in addition to mammals, amphibians, and fish. Numerous copies of full length ERV-Spuma-Spu elements were found in the tuatara genome littered with in-frame stop codons and transposable elements, suggesting that they are indeed endogenous and are not functional. ERV-Spuma-Ppi and ERV-Spuma-Gja, on the other hand, consist solely of a foamy virus-like env gene. Examination of host flanking sequences revealed that they are orthologous, and despite being more than 96 million years old, their env reading frames are fully coding competent with evidence for strong purifying selection to maintain expression and for them likely being transcriptionally active. These make them the oldest EFVs discovered thus far and the first documented EFVs that may have been co-opted for potential cellular functions. Phylogenetic analyses revealed a complex virus–host co-evolutionary history and cross-species transmission routes of ancient FVs.
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Affiliation(s)
- Pakorn Aiewsakun
- Department of Microbiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
| | - Peter Simmonds
- Nuffield Department of Medicine, University of Oxford, South Parks Road, Oxford OX1 3SY, UK
| | - Aris Katzourakis
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3SY, UK.
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Lambert C, Couteaudier M, Gouzil J, Richard L, Montange T, Betsem E, Rua R, Tobaly-Tapiero J, Lindemann D, Njouom R, Mouinga-Ondémé A, Gessain A, Buseyne F. Potent neutralizing antibodies in humans infected with zoonotic simian foamy viruses target conserved epitopes located in the dimorphic domain of the surface envelope protein. PLoS Pathog 2018; 14:e1007293. [PMID: 30296302 PMCID: PMC6193739 DOI: 10.1371/journal.ppat.1007293] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 10/18/2018] [Accepted: 08/23/2018] [Indexed: 12/31/2022] Open
Abstract
Human diseases of zoonotic origin are a major public health problem. Simian foamy viruses (SFVs) are complex retroviruses which are currently spilling over to humans. Replication-competent SFVs persist over the lifetime of their human hosts, without spreading to secondary hosts, suggesting the presence of efficient immune control. Accordingly, we aimed to perform an in-depth characterization of neutralizing antibodies raised by humans infected with a zoonotic SFV. We quantified the neutralizing capacity of plasma samples from 58 SFV-infected hunters against primary zoonotic gorilla and chimpanzee SFV strains, and laboratory-adapted chimpanzee SFV. The genotype of the strain infecting each hunter was identified by direct sequencing of the env gene amplified from the buffy coat with genotype-specific primers. Foamy virus vector particles (FVV) enveloped by wild-type and chimeric gorilla SFV were used to map the envelope region targeted by antibodies. Here, we showed high titers of neutralizing antibodies in the plasma of most SFV-infected individuals. Neutralizing antibodies target the dimorphic portion of the envelope protein surface domain. Epitopes recognized by neutralizing antibodies have been conserved during the cospeciation of SFV with their nonhuman primate host. Greater neutralization breadth in plasma samples of SFV-infected humans was statistically associated with smaller SFV-related hematological changes. The neutralization patterns provide evidence for persistent expression of viral proteins and a high prevalence of coinfection. In conclusion, neutralizing antibodies raised against zoonotic SFV target immunodominant and conserved epitopes located in the receptor binding domain. These properties support their potential role in restricting the spread of SFV in the human population.
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Affiliation(s)
- Caroline Lambert
- Unité d’Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
- UMR CNRS 3569, Institut Pasteur, Paris, France
- Sorbonne Paris Cité, Cellule Pasteur, Université Paris Diderot, Institut Pasteur, Paris, France
| | - Mathilde Couteaudier
- Unité d’Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
- UMR CNRS 3569, Institut Pasteur, Paris, France
| | - Julie Gouzil
- Unité d’Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
- UMR CNRS 3569, Institut Pasteur, Paris, France
| | - Léa Richard
- Unité d’Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
- UMR CNRS 3569, Institut Pasteur, Paris, France
- Sorbonne Paris Cité, Cellule Pasteur, Université Paris Diderot, Institut Pasteur, Paris, France
| | - Thomas Montange
- Unité d’Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
- UMR CNRS 3569, Institut Pasteur, Paris, France
| | - Edouard Betsem
- Unité d’Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
- UMR CNRS 3569, Institut Pasteur, Paris, France
- University of Yaounde I, Yaounde, Cameroon
| | - Réjane Rua
- Unité d’Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
- UMR CNRS 3569, Institut Pasteur, Paris, France
| | - Joelle Tobaly-Tapiero
- CNRS UMR 7212, INSERM U944, Institut Universitaire d’Hématologie, Hôpital Saint-Louis, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Dirk Lindemann
- Institute of Virology, Medical Faculty “Carl Gustav Carus”, Technische Universität Dresden, Dresden, Germany
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | - Richard Njouom
- Laboratoire de Virologie, Centre Pasteur du Cameroun, Yaoundé, Cameroon
| | - Augustin Mouinga-Ondémé
- Unité de Rétrovirologie, Centre International de Recherche Médicale de Franceville, Franceville, Gabon
| | - Antoine Gessain
- Unité d’Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
- UMR CNRS 3569, Institut Pasteur, Paris, France
| | - Florence Buseyne
- Unité d’Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France
- UMR CNRS 3569, Institut Pasteur, Paris, France
- * E-mail:
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Bähr A, Singer A, Hain A, Vasudevan AAJ, Schilling M, Reh J, Riess M, Panitz S, Serrano V, Schweizer M, König R, Chanda S, Häussinger D, Kochs G, Lindemann D, Münk C. Interferon but not MxB inhibits foamy retroviruses. Virology 2016; 488:51-60. [DOI: 10.1016/j.virol.2015.10.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 09/11/2015] [Accepted: 10/31/2015] [Indexed: 11/26/2022]
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Rethwilm A. Specific RNA-protein interactions in the replication of foamy viruses (FVs). Curr Opin Virol 2013; 3:676-83. [PMID: 24119459 DOI: 10.1016/j.coviro.2013.09.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 09/10/2013] [Accepted: 09/10/2013] [Indexed: 11/25/2022]
Abstract
The FV pathway of replication is fundamentally different from what we know about the strategy employed by all known other retroviruses. This unique pathway involves some distinctive RNA-protein interactions, which range from nuclear RNA export to activation of reverse transcription late in the viral replication cycle. Some peculiarities of this replication strategy will be summarized here.
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Affiliation(s)
- Axel Rethwilm
- Universität Würzburg, Institut für Virologie und Immunbiologie, Versbacher Str. 7, 97078 Würzburg, Germany.
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Rethwilm A, Bodem J. Evolution of foamy viruses: the most ancient of all retroviruses. Viruses 2013; 5:2349-74. [PMID: 24072062 PMCID: PMC3814592 DOI: 10.3390/v5102349] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 08/27/2013] [Accepted: 09/18/2013] [Indexed: 12/24/2022] Open
Abstract
Recent evidence indicates that foamy viruses (FVs) are the oldest retroviruses (RVs) that we know and coevolved with their hosts for several hundred million years. This coevolution may have contributed to the non-pathogenicity of FVs, an important factor in development of foamy viral vectors in gene therapy. However, various questions on the molecular evolution of FVs remain still unanswered. The analysis of the spectrum of animal species infected by exogenous FVs or harboring endogenous FV elements in their genome is pivotal. Furthermore, animal studies might reveal important issues, such as the identification of the FV in vivo target cells, which than require a detailed characterization, to resolve the molecular basis of the accuracy with which FVs copy their genome. The issues of the extent of FV viremia and of the nature of the virion genome (RNA vs. DNA) also need to be experimentally addressed.
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Affiliation(s)
- Axel Rethwilm
- Universität Würzburg, Institut für Virologie und Immunbiologie, Versbacher Str.7, Würzburg 97078, Germany.
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Hütter S, Zurnic I, Lindemann D. Foamy virus budding and release. Viruses 2013; 5:1075-98. [PMID: 23575110 PMCID: PMC3705266 DOI: 10.3390/v5041075] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 03/25/2013] [Accepted: 03/29/2013] [Indexed: 12/21/2022] Open
Abstract
Like all other viruses, a successful egress of functional particles from infected cells is a prerequisite for foamy virus (FV) spread within the host. The budding process of FVs involves steps, which are shared by other retroviruses, such as interaction of the capsid protein with components of cellular vacuolar protein sorting (Vps) machinery via late domains identified in some FV capsid proteins. Additionally, there are features of the FV budding strategy quite unique to the spumaretroviruses. This includes secretion of non-infectious subviral particles and a strict dependence on capsid-glycoprotein interaction for release of infectious virions from the cells. Virus-like particle release is not possible since FV capsid proteins lack a membrane-targeting signal. It is noteworthy that in experimental systems, the important capsid-glycoprotein interaction could be bypassed by fusing heterologous membrane-targeting signals to the capsid protein, thus enabling glycoprotein-independent egress. Aside from that, other systems have been developed to enable envelopment of FV capsids by heterologous Env proteins. In this review article, we will summarize the current knowledge on FV budding, the viral components and their domains involved as well as alternative and artificial ways to promote budding of FV particle structures, a feature important for alteration of target tissue tropism of FV-based gene transfer systems.
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Affiliation(s)
- Sylvia Hütter
- Institute of Virology, Medical Faculty "Carl Gustav Carus", Technische Universität Dresden, Fetscherstr. 74, Dresden 01307, Germany; E-Mails: (S.H); (I.Z.)
- DFG-Center for Regenerative Therapies Dresden (CRTD)—Cluster of Excellence, Technische Universität Dresden, Fetscherstr. 105, Dresden 01307, Germany
| | - Irena Zurnic
- Institute of Virology, Medical Faculty "Carl Gustav Carus", Technische Universität Dresden, Fetscherstr. 74, Dresden 01307, Germany; E-Mails: (S.H); (I.Z.)
- DFG-Center for Regenerative Therapies Dresden (CRTD)—Cluster of Excellence, Technische Universität Dresden, Fetscherstr. 105, Dresden 01307, Germany
| | - Dirk Lindemann
- Institute of Virology, Medical Faculty "Carl Gustav Carus", Technische Universität Dresden, Fetscherstr. 74, Dresden 01307, Germany; E-Mails: (S.H); (I.Z.)
- DFG-Center for Regenerative Therapies Dresden (CRTD)—Cluster of Excellence, Technische Universität Dresden, Fetscherstr. 105, Dresden 01307, Germany
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +49-351458-6210; Fax: +49-351-458-6310
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Berka U, Hamann MV, Lindemann D. Early events in foamy virus-host interaction and intracellular trafficking. Viruses 2013; 5:1055-74. [PMID: 23567621 PMCID: PMC3705265 DOI: 10.3390/v5041055] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 03/28/2013] [Accepted: 03/29/2013] [Indexed: 02/08/2023] Open
Abstract
Here we review viral and cellular requirements for entry and intracellular trafficking of foamy viruses (FVs) resulting in integration of viral sequences into the host cell genome. The virus encoded glycoprotein harbors all essential viral determinants, which are involved in absorption to the host membrane and triggering the uptake of virus particles. However, only recently light was shed on some details of FV's interaction with its host cell receptor(s). Latest studies indicate glycosaminoglycans of cellular proteoglycans, particularly heparan sulfate, to be of utmost importance. In a species-specific manner FVs encounter endogenous machineries of the target cell, which are in some cases exploited for fusion and further egress into the cytosol. Mostly triggered by pH-dependent endocytosis, viral and cellular membranes fuse and release naked FV capsids into the cytoplasm. Intact FV capsids are then shuttled along microtubules and are found to accumulate nearby the centrosome where they can remain in a latent state for extended time periods. Depending on the host cell cycle status, FV capsids finally disassemble and, by still poorly characterized mechanisms, the preintegration complex gets access to the host cell chromatin. Host cell mitosis finally allows for viral genome integration, ultimately starting a new round of viral replication.
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Affiliation(s)
- Ursula Berka
- Institute of Virology, Medical Faculty―Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, Dresden 01307, Germany; E-Mails: (U.B.); (M.V.H.)
- DFG-Center for Regenerative Therapies Dresden (CRTD)—Cluster of Excellence, Biotechnology Center, Technische Universität Dresden, Fetscherstr. 105, Dresden 01307, Germany
| | - Martin Volker Hamann
- Institute of Virology, Medical Faculty―Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, Dresden 01307, Germany; E-Mails: (U.B.); (M.V.H.)
- DFG-Center for Regenerative Therapies Dresden (CRTD)—Cluster of Excellence, Biotechnology Center, Technische Universität Dresden, Fetscherstr. 105, Dresden 01307, Germany
| | - Dirk Lindemann
- Institute of Virology, Medical Faculty―Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, Dresden 01307, Germany; E-Mails: (U.B.); (M.V.H.)
- DFG-Center for Regenerative Therapies Dresden (CRTD)—Cluster of Excellence, Biotechnology Center, Technische Universität Dresden, Fetscherstr. 105, Dresden 01307, Germany
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The foamy virus Gag proteins: what makes them different? Viruses 2013; 5:1023-41. [PMID: 23531622 PMCID: PMC3705263 DOI: 10.3390/v5041023] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/15/2013] [Accepted: 03/20/2013] [Indexed: 12/15/2022] Open
Abstract
Gag proteins play an important role in many stages of the retroviral replication cycle. They orchestrate viral assembly, interact with numerous host cell proteins, engage in regulation of viral gene expression, and provide the main driving force for virus intracellular trafficking and budding. Foamy Viruses (FV), also known as spumaviruses, display a number of unique features among retroviruses. Many of these features can be attributed to their Gag proteins. FV Gag proteins lack characteristic orthoretroviral domains like membrane-binding domains (M domains), the major homology region (MHR), and the hallmark Cys-His motifs. In contrast, they contain several distinct domains such as the essential Gag-Env interaction domain and the glycine and arginine rich boxes (GR boxes). Furthermore, FV Gag only undergoes limited maturation and follows an unusual pathway for nuclear translocation. This review summarizes the known FV Gag domains and motifs and their functions. In particular, it provides an overview of the unique structural and functional properties that distinguish FV Gag proteins from orthoretroviral Gag proteins.
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Abstract
The retrovirus family contains several important human and animal pathogens, including the human immunodeficiency virus (HIV), the causative agent of acquired immunodeficiency syndrome (AIDS). Studies with retroviruses were instrumental to our present understanding of the cellular entry of enveloped viruses in general. For instance, studies with alpharetroviruses defined receptor engagement, as opposed to low pH, as a trigger for the envelope protein-driven membrane fusion. The insights into the retroviral entry process allowed the generation of a new class of antivirals, entry inhibitors, and these therapeutics are at present used for treatment of HIV/AIDS. In this chapter, we will summarize key concepts established for entry of avian sarcoma and leukosis virus (ASLV), a widely used model system for retroviral entry. We will then review how foamy virus and HIV, primate- and human retroviruses, enter target cells, and how the interaction of the viral and cellular factors involved in the cellular entry of these viruses impacts viral tropism, pathogenesis and approaches to therapy and vaccine development.
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Abstract
Simian foamy viruses (SFVs) are retroviruses that are widespread among nonhuman primates (NHPs). SFVs actively replicate in their oral cavity and can be transmitted to humans after NHP bites, giving rise to a persistent infection even decades after primary infection. Very few data on the genetic structure of such SFVs found in humans are available. In the framework of ongoing studies searching for SFV-infected humans in south Cameroon rainforest villages, we studied 38 SFV-infected hunters whose times of infection had presumably been determined. By long-term cocultures of peripheral blood mononuclear cells with BHK-21 cells, we isolated five new SFV strains and obtained complete genomes of SFV strains from chimpanzee (Pan troglodytes troglodytes; strains BAD327 and AG15), monkey (Cercopithecus nictitans; strain AG16), and gorilla (Gorilla gorilla; strains BAK74 and BAD468). These zoonotic strains share a very high degree of similarity with their NHP counterparts and have a high degree of conservation of the genetic elements important for viral replication. Interestingly, analysis of FV DNA sequences obtained before cultivation revealed variants with deletions in both the U3 region and tas that may correlate with in vivo chronicity in humans. Genomic changes in bet (a premature stop codon) and gag were also observed. To determine if such changes were specific to zoonotic strains, we studied local SFV-infected chimpanzees and found the same genomic changes. Our study reveals that natural polymorphism of SFV strains does exist at both the intersubspecies level (gag, bet) and the intrasubspecies (U3, tas) levels but does not seem to reflect a viral adaptation specific to zoonotic SFV strains.
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Lindemann D, Rethwilm A. Foamy virus biology and its application for vector development. Viruses 2011; 3:561-85. [PMID: 21994746 PMCID: PMC3185757 DOI: 10.3390/v3050561] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 04/21/2011] [Accepted: 04/23/2011] [Indexed: 01/12/2023] Open
Abstract
Spuma- or foamy viruses (FV), endemic in most non-human primates, cats, cattle and horses, comprise a special type of retrovirus that has developed a replication strategy combining features of both retroviruses and hepadnaviruses. Unique features of FVs include an apparent apathogenicity in natural hosts as well as zoonotically infected humans, a reverse transcription of the packaged viral RNA genome late during viral replication resulting in an infectious DNA genome in released FV particles and a special particle release strategy depending capsid and glycoprotein coexpression and specific interaction between both components. In addition, particular features with respect to the integration profile into the host genomic DNA discriminate FV from orthoretroviruses. It appears that some inherent properties of FV vectors set them favorably apart from orthoretroviral vectors and ask for additional basic research on the viruses as well as on the application in Gene Therapy. This review will summarize the current knowledge of FV biology and the development as a gene transfer system.
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Affiliation(s)
- Dirk Lindemann
- Institut für Virologie, Medizinische Fakultät “Carl Gustav Carus”, Technische Universität Dresden, Fetscherstr. 74, 01307 Dresden, Germany
- DFG-Center for Regenerative Therapies Dresden (CRTD)—Cluster of Excellence, Biotechnology Center, Technische Universität Dresden, Fetscherstr. 74, 01307 Dresden, Germany
| | - Axel Rethwilm
- Institut für Virologie und Immunbiologie, Universität Würzburg, 97078 Würzburg, Germany; E-Mail:
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