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Cardona SM, Dunphy JM, Das AS, Lynch CR, Lynch WP. Astrocyte Infection Is Required for Retrovirus-Induced Spongiform Neurodegeneration Despite Suppressed Viral Protein Expression. Front Neurosci 2019; 13:1166. [PMID: 31736699 PMCID: PMC6828646 DOI: 10.3389/fnins.2019.01166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 10/15/2019] [Indexed: 12/17/2022] Open
Abstract
The ability of retroviruses (RVs) to cause neurodegeneration is critically dependent upon two activities of the envelope protein (Env). First, Env facilitates viral genome delivery to CNS target cells through receptor binding and membrane fusion. Second, Env expression within one or more targets indirectly alters the physiology of certain neurons. Although the major Env expressing CNS cell types have been identified for many neurovirulent RVs, it remains unresolved, which targets play a causal role in neuropathogenesis. Moreover, this issue is complicated by the potential for post-infection virus suppression. To address these questions we explored herein, whether and how cryptic neurotropism differences between ecotropic and amphotropic murine leukemia viruses (MLVs) impacted neurovirulence. Neurotropism was first explored ex vivo using (1) acute primary glial cell cultures and (2) neural progenitor cell (NPC)- neural stem cell (NSC) neural sphere (NPH) chimeras. These experiments indicated that primary astrocytes and NPCs acutely restrict amphotropic but not ecotropic virus entry. CNS tropism was investigated using NSC transplant-based Cre-vector pseudotyping wherein mTmG transgenic fluorescent protein reporter mice revealed both productive and suppressed infection. Cre-pseudotyping with FrCasE, a prototypic neurovirulent ecotropic virus, identified glia and endothelia, but not neurons, as targets. Almost two-thirds (62%) of mGFP+ cells failed to show Env expression, suggesting widespread virus suppression. To circumvent RV superinfection interference confounds, targets were also identified using ecotropic packaging NSCs. These experiments identified known ecotropic targets: microglia, oligodendrocyte progenitor cells (OPCs) and endothelia. Additionally, one third of mGFP+ cells were identified as protoplasmic astrocytes, cells that rarely express virus in vivo. A CNS targeting comparison between isogenic ecotropic (FrCasE) and amphotropic (FrAmE) viruses showed a fourfold higher astrocyte targeting by FrCasE. Since ecotropic Env pseudotyping of amphotropic virus in the CNS dramatically exacerbates neurodegeneration, these results strongly suggest that astrocyte infection is a major disease requirement. Moreover, since viral Env protein expression is largely subdetectable in astrocytes, minimal viral protein expression appears sufficient for affecting neuronal physiology. More broadly, these findings raise the specter that subdetectable astrocyte expression of exogenous or endogenous RVs could play a major role in human and animal neurodegenerative diseases.
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Affiliation(s)
- Sandra M Cardona
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, United States.,Program in Cellular and Molecular Biology, School of Biomedical Sciences, Kent State University, Kent, OH, United States
| | - Jaclyn M Dunphy
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, United States.,Program in Neuroscience, School of Biomedical Sciences, Kent State University, Kent, OH, United States
| | - Alvin S Das
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Connor R Lynch
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, United States
| | - William P Lynch
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, United States.,Program in Cellular and Molecular Biology, School of Biomedical Sciences, Kent State University, Kent, OH, United States.,Program in Neuroscience, School of Biomedical Sciences, Kent State University, Kent, OH, United States.,Brain Health Research Institute, Kent State University, Kent, OH, United States
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Ledoux JM. Hypothesis of interference to superinfection between bovine spastic paresis and bovine spongiform encephalopathy; suggestions for experimentation, theoretical and practical interest. Med Hypotheses 2004; 62:346-53. [PMID: 14975501 DOI: 10.1016/j.mehy.2003.11.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2003] [Accepted: 11/21/2003] [Indexed: 11/16/2022]
Abstract
Sub-acute transmissible spongiform encephalopathies (TSEs) or prion diseases are diseases of little known etiology. The origin of these diseases would appear to be an abnormal protease-resistant prion protein (PrP(res)) which would be infectious by directly inducing its defective conformation to the normal native protein (PrP(C)). This hypothesis does not account for certain aspects of TSEs, such as interference to superinfection: in laboratory animals, inoculation by means of an attenuated strain with a long incubation period protects against later infection by a very virulent strain with a short incubation period. The hypothesis is put forward that there exists a possibility of interference to superinfection between neurodegenerative diseases of unknown origin, thought to be similar to TSEs, and a later infection by a TSE. The study of this interference between bovine spastic paresis (BSP) and bovine spongiform encephalopathy (BSE) could be used as a model for this hypothesis. BSP is a very rare disease among cattle, of unknown etiology; it is curable, in the very early stages, by using tryptophan and especially lithium, potentiated by copper and manganese. An etiology close to that of TSEs has been suggested on several occasions. If interference could be demonstrated between BSP and BSE, interesting data would be provided concerning the etiology, the pathogenesis and possibly the treatment and prevention of these diseases. Notably, such data could lead to the development of a treatment and a prevention with lithium and amino acids precursors of neuromediators (tryptophan, tyrosine, glutamic acid, etc.), as well as the developing of a vaccine to combat TSEs, especially BSE and scrapie.
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Münk C, Prassolov V, Rodenburg M, Kalinin V, Löhler J, Stocking C. 10A1-MuLV but not the related amphotropic 4070A MuLV is highly neurovirulent: importance of sequences upstream of the structural Gag coding region. Virology 2003; 313:44-55. [PMID: 12951020 DOI: 10.1016/s0042-6822(03)00210-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recombinants of Moloney murine leukemia virus (MoMuLV) with either an amphotropic (MoAmphoV) or 10A1-tropic host range (Mo10A1V) induce a spongiform neurodegenerative disease in susceptible mice. To test whether MoMuLV -derived sequences are required for induction of neuropathology, mice were inoculated with either the original 10A1 or the amphotropic (4070A) MuLV isolate. Strikingly, wild-type 10A1 was more neurovirulent than Mo10A1V, inducing severe neurological clinical symptoms with a median latency of 99 days in 100% of infected mice. In contrast, no motor disturbances were detected in any of the 4070A-infected mice, although limited central nervous system lesions were observed. A viral determinant conferring high neurovirulence to 10A1 was mapped to a region encompassing the first 676 bases of the viral genome, including the U5 LTR and encoding the amino-terminus of glycosylated Gag (glycoGag). In contrast to studies with the highly neurovirulent CasFr(KP) virus, an inverse correlation between surface expression levels of glycoGag and neurovirulence was not observed; however, this does not rule out a common underlying mechanism regulating virus pathogenicity.
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Affiliation(s)
- Carsten Münk
- Department of Cell and Virus Genetics, Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie, D-20251 Hamburg, Germany
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Prassolov V, Ivanov D, Hein S, Rutter G, Münk C, Löhler J, Stocking C. The Mus cervicolor MuLV isolate M813 is highly fusogenic and induces a T-cell lymphoma associated with large multinucleated cells. Virology 2001; 290:39-49. [PMID: 11883004 DOI: 10.1006/viro.2001.1145] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
M813 is a type-C murine leukemia virus (MuLV) isolated from the Asian rodent Mus cervicolor. We have recently demonstrated that M813 defines a distinct MuLV receptor interference group. Here we show that M813 rapidly induces fusion of MuLV-expressing fibroblasts from "without," with syncytia being observed within 1 h after exposure to virus. Infection of fibroblasts with MuLV from all tested receptor-interference groups imparts susceptibility to M813-induced fusion, provided the cells also express the M813 receptor. Syncytium induction is also observed in vivo; mice infected with M813 develop a peripheral T-cell lymphoma, which is associated with large multinucleated cells of macrophage origin. A recombinant Moloney MuLV/M813 chimeric virus demonstrated that syncytium induction is a function of the Env SU protein. We postulate that the highly fusogenic property of M813 is attributable to either its unique receptor usage or sequences in the proline-rich domain of the Env protein.
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Affiliation(s)
- V Prassolov
- Heinrich-Pette-Institut für Experimentelle Immunologie und Virologie an der Universität Hamburg, Martinistrasse 52, D-20251 Hamburg, Germany
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Prassolov V, Hein S, Ziegler M, Ivanov D, Münk C, Löhler J, Stocking C. Mus cervicolor murine leukemia virus isolate M813 belongs to a unique receptor interference group. J Virol 2001; 75:4490-8. [PMID: 11312319 PMCID: PMC114202 DOI: 10.1128/jvi.75.10.4490-4498.2001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Murine leukemia virus (MuLV) M813 was originally isolated from the Southeast Asian rodent Mus cervicolor. As with the ecotropic MuLVs derived from Mus musculus, its host range is limited to rodent cells. Earlier studies have mapped its receptor to chromosome 2, but it has not been established whether M813 shares a common receptor with any other MuLVs. In this study, we have performed interference assays with M813 and viruses from four interference groups of MuLV. The infection efficiency of M813 was not compromised in cells expressing any one of the other MuLVs, demonstrating that M813 must use a distinct receptor for cell entry. The entire M813 env coding region was molecularly cloned. Sequence analysis revealed high similarity with other MuLVs but with a unique receptor-binding domain. Substitution of M813 env sequences in Moloney MuLV resulted in a replication-competent virus with a host range and interference profile similar to those of the biological clone M813. M813 thus defines a novel receptor interference group of type C MuLVs.
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MESH Headings
- 3T3 Cells
- Amino Acid Sequence
- Amino Acid Transport Systems, Basic
- Animals
- Base Sequence
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Cells, Cultured
- Cloning, Molecular
- DNA, Viral
- Gene Products, env/classification
- Gene Products, env/genetics
- Genes, Viral
- HeLa Cells
- Humans
- Leukemia Virus, Murine/classification
- Leukemia Virus, Murine/genetics
- Leukemia Virus, Murine/isolation & purification
- Leukemia Virus, Murine/physiology
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mice/virology
- Molecular Sequence Data
- Moloney murine leukemia virus/metabolism
- Muridae/virology
- Mutagenesis
- Rats
- Receptors, Virus/genetics
- Receptors, Virus/metabolism
- Retroviridae Infections/veterinary
- Retroviridae Infections/virology
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Tumor Virus Infections/veterinary
- Tumor Virus Infections/virology
- Viral Interference
- Virus Replication
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Affiliation(s)
- V Prassolov
- Engelhardt Institute of Molecular Biology, Moscow, Russia
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