1
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Chambers IG, Willoughby MM, Hamza I, Reddi AR. One ring to bring them all and in the darkness bind them: The trafficking of heme without deliverers. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2021; 1868:118881. [PMID: 33022276 PMCID: PMC7756907 DOI: 10.1016/j.bbamcr.2020.118881] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 09/22/2020] [Accepted: 09/25/2020] [Indexed: 02/07/2023]
Abstract
Heme, as a hydrophobic iron-containing organic ring, is lipid soluble and can interact with biological membranes. The very same properties of heme that nature exploits to support life also renders heme potentially cytotoxic. In order to utilize heme, while also mitigating its toxicity, cells are challenged to tightly control the concentration and bioavailability of heme. On the bright side, it is reasonable to envision that, analogous to other transition metals, a combination of membrane-bound transporters, soluble carriers, and chaperones coordinate heme trafficking to subcellular compartments. However, given the dual properties exhibited by heme as a transition metal and lipid, it is compelling to consider the dark side: the potential role of non-proteinaceous biomolecules including lipids and nucleic acids that bind, sequester, and control heme trafficking and bioavailability. The emergence of inter-organellar membrane contact sites, as well as intracellular vesicles derived from various organelles, have raised the prospect that heme can be trafficked through hydrophobic channels. In this review, we aim to focus on heme delivery without deliverers - an alternate paradigm for the regulation of heme homeostasis through chaperone-less pathways for heme trafficking.
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Affiliation(s)
- Ian G Chambers
- Department of Animal and Avian Sciences, Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20740, United States of America
| | - Mathilda M Willoughby
- School of Chemistry and Biochemistry, Parker Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, United States of America
| | - Iqbal Hamza
- Department of Animal and Avian Sciences, Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20740, United States of America.
| | - Amit R Reddi
- School of Chemistry and Biochemistry, Parker Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, United States of America.
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2
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Studer N, Lutz H, Saegerman C, Gönczi E, Meli ML, Boo G, Hartmann K, Hosie MJ, Moestl K, Tasker S, Belák S, Lloret A, Boucraut-Baralon C, Egberink HF, Pennisi MG, Truyen U, Frymus T, Thiry E, Marsilio F, Addie D, Hochleithner M, Tkalec F, Vizi Z, Brunetti A, Georgiev B, Ludwig-Begall LF, Tschuor F, Mooney CT, Eliasson C, Orro J, Johansen H, Juuti K, Krampl I, Kovalenko K, Šengaut J, Sobral C, Borska P, Kovaříková S, Hofmann-Lehmann R. Pan-European Study on the Prevalence of the Feline Leukaemia Virus Infection - Reported by the European Advisory Board on Cat Diseases (ABCD Europe). Viruses 2019; 11:v11110993. [PMID: 31671816 PMCID: PMC6893802 DOI: 10.3390/v11110993] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/26/2019] [Accepted: 10/27/2019] [Indexed: 01/09/2023] Open
Abstract
Feline leukaemia virus (FeLV) is a retrovirus associated with fatal disease in progressively infected cats. While testing/removal and vaccination led to a decreased prevalence of FeLV, recently, this decrease has reportedly stagnated in some countries. This study aimed to prospectively determine the prevalence of FeLV viraemia in cats taken to veterinary facilities in 32 European countries. FeLV viral RNA was semiquantitatively detected in saliva, using RT-qPCR as a measure of viraemia. Risk and protective factors were assessed using an online questionnaire to report geographic, demographic, husbandry, FeLV vaccination, and clinical data. The overall prevalence of FeLV viraemia in cats visiting a veterinary facility, of which 10.4% were shelter and rescue cats, was 2.3% (141/6005; 95% CI: 2.0%–2.8%) with the highest prevalences in Portugal, Hungary, and Italy/Malta (5.7%–8.8%). Using multivariate analysis, seven risk factors (Southern Europe, male intact, 1–6 years of age, indoor and outdoor or outdoor-only living, living in a group of ≥5 cats, illness), and three protective factors (Northern Europe, Western Europe, pedigree cats) were identified. Using classification and regression tree (CART) analysis, the origin of cats in Europe, pedigree, and access to outdoors were important predictors of FeLV status. FeLV-infected sick cats shed more viral RNA than FeLV-infected healthy cats, and they suffered more frequently from anaemia, anorexia, and gingivitis/stomatitis than uninfected sick cats. Most cats had never been FeLV-vaccinated; vaccination rates were indirectly associated with the gross domestic product (GDP) per capita. In conclusion, we identified countries where FeLV was undetectable, demonstrating that the infection can be eradicated and highlighting those regions where awareness and prevention should be increased.
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Affiliation(s)
- Nadine Studer
- Clinical Laboratory, Department of Clinical Diagnostics and Services, and Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland.
| | - Hans Lutz
- Clinical Laboratory, Department of Clinical Diagnostics and Services, and Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland.
| | - Claude Saegerman
- Department of Infectious and Parasitic Diseases, Research Unit of Epidemiology and Risk Analysis Applied to Veterinary, Fundamental and Applied Research for Animal and Health (FARAH) Center, Faculty of Veterinary Medicine, University of Liège, B-4000 Liège, Belgium.
| | - Enikö Gönczi
- Clinical Laboratory, Department of Clinical Diagnostics and Services, and Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland.
| | - Marina L Meli
- Clinical Laboratory, Department of Clinical Diagnostics and Services, and Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland.
| | - Gianluca Boo
- Department of Geography, University of Zurich, 8057 Zurich, Switzerland.
| | - Katrin Hartmann
- Clinic of Small Animal Medicine, Centre for Clinical Veterinary Medicine, LMU Munich, 80539 Munich, Germany.
| | - Margaret J Hosie
- MRC- University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK.
| | - Karin Moestl
- Institute of Virology, Department for Pathobiology, University of Veterinary Medicine, 1210 Vienna, Austria.
| | - Séverine Tasker
- Bristol Veterinary School, University of Bristol, Bristol BS40 5DU, UK & Chief Medical Officer, Linnaeus Group, Shirley, Solihull B90 4BN, UK.
| | - Sándor Belák
- Swedish University of Agricultural Sciences (SLU), Department of Biomedical Sciences and Veterinary Public Health (BVF), 750 07 Uppsala, Sweden.
| | - Albert Lloret
- Fundació Hospital Clínic Veterinari, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
| | | | - Herman F Egberink
- University of Utrecht, Faculty of Veterinary Medicine, Department of Infectious Diseases and Immunology, 3584 CL Utrecht, Netherlands.
| | - Maria-Grazia Pennisi
- Dipartimento di Scienze Veterinarie, Università di Messina, 98168 Messina, Italy.
| | - Uwe Truyen
- Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, 04103 Leipzig, Germany.
| | - Tadeusz Frymus
- Department of Small Animal Diseases with Clinic, Faculty of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, 02-787 Warsaw, Poland.
| | - Etienne Thiry
- Veterinary Virology and Animal Viral Diseases, Department of Infectious and Parasitic Diseases, FARAH Research Centre, Faculty of Veterinary Medicine, Liège University, B-4000 Liège, Belgium.
| | - Fulvio Marsilio
- Faculty of Veterinary Medicine, Università degli Studi di Teramo, 64100 Teramo, Italy.
| | - Diane Addie
- Veterinary Diagnostic Services, School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK.
| | | | - Filip Tkalec
- Veterinarska klinika Kreszinger, 10360 Sesvete, Zagreb, Croatia.
| | - Zsuzsanna Vizi
- University of Veterinary Medicine, 1078 Budapest, Hungary.
| | - Anna Brunetti
- School of Veterinary Medicine, University of Glasgow, Glasgow G61 1QH, UK.
| | - Boyko Georgiev
- Institute of Biology and Immunology of Reproduction, 1113 Sofia, Bulgaria.
| | - Louisa F Ludwig-Begall
- Veterinary Virology and Animal Viral Diseases, Department of Infectious and Parasitic Diseases, FARAH Research Centre, Faculty of Veterinary Medicine, Liège University, B-4000 Liège, Belgium.
| | - Flurin Tschuor
- Kleintierklinik BolligerTschuor AG, Fachtierärzte für Kleintiere, 4665 Oftringen - Zofingen, Switzerland.
| | - Carmel T Mooney
- School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
| | - Catarina Eliasson
- Jamaren - Swedish Veterinary Feline Study Group, 275 71 Lövestad, Sweden.
| | | | | | - Kirsi Juuti
- CatVet Kissaklinikka, 00400 Helsinki, Finland.
| | - Igor Krampl
- Slovak Small Animal Veterinary Association, 821 02 Bratislava, Slovakia.
| | - Kaspars Kovalenko
- Faculty of Veterinary Medicine, Latvia University of Lifesciences and Technologies, LV-3004 Jelgava, Latvia.
| | - Jakov Šengaut
- Jakov Veterinary Centre, Gerosios Vilties g. 1, LT-03147 Vilnius, Lithuania.
| | | | - Petra Borska
- Small Animal Emergency Clinic, 637 00 Brno-Jundrov, Czech Republic.
| | - Simona Kovaříková
- Department of Animal Protection, Welfare and Behavior, Faculty of Veterinary Hygiene and Ecology, University of Veterinary and Pharmaceutical Sciences Brno, 612 42 Brno, Czech Republic.
| | - Regina Hofmann-Lehmann
- Clinical Laboratory, Department of Clinical Diagnostics and Services, and Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland.
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3
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Feline Leukemia Virus (FeLV) Disease Outcomes in a Domestic Cat Breeding Colony: Relationship to Endogenous FeLV and Other Chronic Viral Infections. J Virol 2018; 92:JVI.00649-18. [PMID: 29976676 DOI: 10.1128/jvi.00649-18] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/26/2018] [Indexed: 01/15/2023] Open
Abstract
Exogenous feline leukemia virus (FeLV) is a feline gammaretrovirus that results in a variety of disease outcomes. Endogenous FeLV (enFeLV) is a replication-defective provirus found in species belonging to the Felis genus, which includes the domestic cat (Felis catus). There have been few studies examining interaction between enFeLV genotype and FeLV progression. We examined point-in-time enFeLV and FeLV viral loads, as well as occurrence of FeLV/enFeLV recombinants (FeLV-B), to determine factors relating to clinical disease in a closed breeding colony of cats during a natural infection of FeLV. Coinfections with feline foamy virus (FFV), feline gammaherpesvirus 1 (FcaGHV-1), and feline coronavirus (FCoV) were also documented and analyzed for impact on cat health and FeLV disease. Correlation analysis and structural equation modeling techniques were used to measure interactions among disease parameters. Progressive FeLV disease and FeLV-B presence were associated with higher FeLV proviral and plasma viral loads. Female cats were more likely to have progressive disease and FeLV-B. Conversely, enFeLV copy number was higher in male cats and negatively associated with progressive FeLV disease. Males were more likely to have abortive FeLV disease. FFV proviral load was found to correlate positively with higher FeLV proviral and plasma viral load, detection of FeLV-B, and FCoV status. Male cats were much more likely to be infected with FcaGHV-1 than female cats. This analysis provides insights into the interplay between endogenous and exogenous FeLV during naturally occurring disease and reveals striking variation in the infection patterns among four chronic viral infections of domestic cats.IMPORTANCE Endogenous retroviruses are harbored by many animals, and their interactions with exogenous retroviral infections have not been widely studied. Feline leukemia virus (FeLV) is a relevant model system to examine this question, as endogenous and exogenous forms of the virus exist. In this analysis of a large domestic cat breeding colony naturally infected with FeLV, we documented that enFeLV copy number was higher in males and inversely related to FeLV viral load and associated with better FeLV disease outcomes. Females had lower enFeLV copy numbers and were more likely to have progressive FeLV disease and FeLV-B subtypes. FFV viral load was correlated with FeLV progression. FFV, FcaGHV-1, and FeLV displayed markedly different patterns of infection with respect to host demographics. This investigation revealed complex coinfection outcomes and viral ecology of chronic infections in a closed population.
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4
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Ponka P, Sheftel AD, English AM, Scott Bohle D, Garcia-Santos D. Do Mammalian Cells Really Need to Export and Import Heme? Trends Biochem Sci 2017; 42:395-406. [PMID: 28254242 DOI: 10.1016/j.tibs.2017.01.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/13/2017] [Accepted: 01/26/2017] [Indexed: 01/07/2023]
Abstract
Heme is a cofactor that is essential to almost all forms of life. The production of heme is a balancing act between the generation of the requisite levels of the end-product and protection of the cell and/or organism against any toxic substrates, intermediates and, in this case, end-product. In this review, we provide an overview of our understanding of the formation and regulation of this metallocofactor and discuss new research on the cell biology of heme homeostasis, with a focus on putative transmembrane transporters now proposed to be important regulators of heme distribution. The main text is complemented by a discussion dedicated to the intricate chemistry and biochemistry of heme, which is often overlooked when new pathways of heme transport are conceived.
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Affiliation(s)
- Prem Ponka
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, QC, H3T 1E2, Canada; Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada.
| | - Alex D Sheftel
- Spartan Bioscience Inc., Ottawa, ON, K2H 1B2, Canada; High Impact Editing, Ottawa, ON, K1B 3Y6, Canada
| | - Ann M English
- Department of Chemistry and Biochemistry, Centre for Research in Molecular Modeling and PROTEO, Concordia University, Montréal, QC, H4B 1R, Canada
| | - D Scott Bohle
- Department of Chemistry, McGill University, Montréal, QC, H3A 0B8, Canada
| | - Daniel Garcia-Santos
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, QC, H3T 1E2, Canada; Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada
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5
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Khan AA, Quigley JG. Heme and FLVCR-related transporter families SLC48 and SLC49. Mol Aspects Med 2013; 34:669-82. [PMID: 23506900 DOI: 10.1016/j.mam.2012.07.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 03/14/2012] [Indexed: 12/11/2022]
Abstract
Heme is critical for a variety of cellular processes, but excess intracellular heme may result in oxidative stress and membrane injury. Feline leukemia virus subgroup C receptor (FLVCR1), a member of the SLC49 family of four paralogous genes, is a cell surface heme exporter, essential for erythropoiesis and systemic iron homeostasis. Disruption of FLVCR1 function blocks development of erythroid progenitors, likely due to heme toxicity. Mutations of SLC49A1 encoding FLVCR1 are noted in patients with a rare neurodegenerative disorder: posterior column ataxia with retinitis pigmentosa. FLVCR2 is highly homologous to FLVCR1 and may function as a cellular heme importer. Mutations of SLC49A2 encoding FLVCR2 are observed in Fowler syndrome, a rare proliferative vascular disorder of the brain. The functions of the remaining members of the SLC49 family, MFSD7 and DIRC2 (encoded by the SLC49A3 and SLC49A4 genes), are unknown, although the latter is implicated in hereditary renal carcinomas. SLC48A1 (heme responsive gene-1, HRG-1), the sole member of the SLC48 family, is associated with the endosome and appears to transport heme from the endosome into the cytosol.
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Affiliation(s)
- Anwar A Khan
- Department of Medicine, Section of Hematology/Oncology, University of Illinois at Chicago, Chicago, IL, USA.
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6
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Khan AA, Quigley JG. Control of intracellular heme levels: heme transporters and heme oxygenases. BIOCHIMICA ET BIOPHYSICA ACTA 2011; 1813:668-82. [PMID: 21238504 PMCID: PMC3079059 DOI: 10.1016/j.bbamcr.2011.01.008] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2010] [Revised: 12/31/2010] [Accepted: 01/06/2011] [Indexed: 12/19/2022]
Abstract
Heme serves as a co-factor in proteins involved in fundamental biological processes including oxidative metabolism, oxygen storage and transport, signal transduction and drug metabolism. In addition, heme is important for systemic iron homeostasis in mammals. Heme has important regulatory roles in cell biology, yet excessive levels of intracellular heme are toxic; thus, mechanisms have evolved to control the acquisition, synthesis, catabolism and expulsion of cellular heme. Recently, a number of transporters of heme and heme synthesis intermediates have been described. Here we review aspects of heme metabolism and discuss our current understanding of heme transporters, with emphasis on the function of the cell-surface heme exporter, FLVCR. Knockdown of Flvcr in mice leads to both defective erythropoiesis and disturbed systemic iron homeostasis, underscoring the critical role of heme transporters in mammalian physiology. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.
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Affiliation(s)
- Anwar A. Khan
- Department of Medicine, Section of Hematology/Oncology, University of Illinois College of Medicine, 909 South Wolcott Avenue, Chicago, IL-60612
| | - John G. Quigley
- Department of Medicine, Section of Hematology/Oncology, University of Illinois College of Medicine, 909 South Wolcott Avenue, Chicago, IL-60612
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7
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Doty RT, Sabo KM, Chen J, Miller AD, Abkowitz JL. An all-feline retroviral packaging system for transduction of human cells. Hum Gene Ther 2011; 21:1019-27. [PMID: 20222826 DOI: 10.1089/hum.2010.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract The subgroup C feline leukemia virus (FeLV-C) receptor FLVCR is a widely expressed 12-transmembrane domain transporter that exports cytoplasmic heme and is a promising target for retrovirus-mediated gene delivery. Previous studies demonstrated that FeLV-C pseudotype vectors were more efficient at targeting human hematopoietic stem cells than those pseudotyped with gibbon ape leukemia virus (GALV), and thus we developed an all FeLV-C-based packaging system, termed CatPac. CatPac is helper-virus free and can produce higher titer vectors than existing gammaretroviral packaging systems, including systems mixing Moloney murine leukemia virus (MoMLV) Gag-Pol and FeLV-C Env proteins. The vectors can be readily concentrated (>30-fold), refrozen (three to five times), and held on ice (>2 days) with little loss of titer. Furthermore, we demonstrate that CatPac pseudotype vectors efficiently target early CD34(+)CD38(-) stem/progenitor cells, monocytic and erythroid progenitors, activated T cells, mature macrophages, and cancer cell lines, suggesting utility for human cell and cell line transduction and possibly gene therapy.
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Affiliation(s)
- Raymond T Doty
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
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8
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Abstract
Mutations in FLVCR2, a cell surface protein related by homology and membrane topology to the heme exporter/retroviral receptor FLVCR1, have recently been associated with Fowler syndrome, a vascular disorder of the brain. We previously identified FLVCR2 to function as a receptor for FY981 feline leukemia virus (FeLV). However, the cellular function of FLVCR2 remains unresolved. Here, we report the cellular function of FLVCR2 as an importer of heme, based on the following observations. First, FLVCR2 binds to hemin-conjugated agarose, and binding is competed by free hemin. Second, mammalian cells and Xenopus laevis oocytes expressing FLVCR2 display enhanced heme uptake. Third, heme import is reduced after the expression of FLVCR2-specific small interfering RNA (siRNA) or after the binding of the FY981 FeLV envelope protein to the FLVCR2 receptor. Finally, cells overexpressing FLVCR2 are more sensitive to heme toxicity, a finding most likely attributable to enhanced heme uptake. Tissue expression analysis indicates that FLVCR2 is expressed in a broad range of human tissues, including liver, placenta, brain, and kidney. The identification of a cellular function for FLVCR2 will have important implications in elucidating the pathogenic mechanisms of Fowler syndrome and of phenotypically associated disorders.
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9
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Does a feline leukemia virus infection pave the way for Bartonella henselae infection in cats? J Clin Microbiol 2010; 48:3295-300. [PMID: 20610682 DOI: 10.1128/jcm.00750-10] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Domestic cats serve as the reservoir hosts of Bartonella henselae and may develop mild clinical symptoms or none after experimental infection. In humans, B. henselae infection can result in self-limiting cat scratch disease. However, immunocompromised patients may suffer from more-severe courses of infection or may even develop the potentially lethal disease bacillary angiomatosis. It was reasoned that cats with immunocompromising viral infections may react similarly to B. henselae infection. The aim of our study was to investigate the influence of the most important viruses known to cause immunosuppression in cats-Feline leukemia virus (FeLV), Feline immunodeficiency virus (FIV), and Feline panleukopenia virus (FPV)-on natural B. henselae infection in cats. Accordingly, 142 cats from animal shelters were necropsied and tested for B. henselae and concurrent infections with FeLV, FIV, or FPV by PCR and immunohistochemistry. A significant association was found between B. henselae and FeLV infections (P = 0.00028), but not between B. henselae and FIV (P = 1.0) or FPV (P = 0.756) infection, age (P = 0.392), or gender (P = 0.126). The results suggest that susceptibility to B. henselae infection is higher in cats with concurrent FeLV infections, regardless of whether the infection is latent or progressive. Histopathology and immunohistochemistry for B. henselae failed to identify lesions that could be attributed specifically to B. henselae infection. We conclude that the course of natural B. henselae infection in cats does not seem to be influenced by immunosuppressive viral infections in general but that latent FeLV infection may predispose cats to B. henselae infection or persistence.
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10
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Gleich S, Hartmann K. Hematology and Serum Biochemistry of Feline Immunodeficiency Virus-Infected and Feline Leukemia Virus-Infected Cats. J Vet Intern Med 2009; 23:552-8. [DOI: 10.1111/j.1939-1676.2009.0303.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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11
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Identification of a feline leukemia virus variant that can use THTR1, FLVCR1, and FLVCR2 for infection. J Virol 2009; 83:6706-16. [PMID: 19369334 DOI: 10.1128/jvi.02317-08] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The pathogenic subgroup C feline leukemia virus (FeLV-C) arises in infected cats as a result of mutations in the envelope (Env) of the subgroup A FeLV (FeLV-A). To better understand emergence of FeLV-C and potential FeLV intermediates that may arise, we characterized FeLV Env sequences from the primary FY981 FeLV isolate previously derived from an anemic cat. Here, we report the characterization of the novel FY981 FeLV Env that is highly related to FeLV-A Env but whose variable region A (VRA) receptor recognition sequence partially resembles the VRA sequence from the prototypical FeLV-C/Sarma Env. Pseudotype viruses bearing FY981 Env were capable of infecting feline, human, and guinea pig cells, suggestive of a subgroup C phenotype, but also infected porcine ST-IOWA cells that are normally resistant to FeLV-C and to FeLV-A. Analysis of the host receptor used by FY981 suggests that FY981 can use both the FeLV-C receptor FLVCR1 and the feline FeLV-A receptor THTR1 for infection. However, our results suggest that FY981 infection of ST-IOWA cells is not mediated by the porcine homologue of FLVCR1 and THTR1 but by an alternative receptor, which we have now identified as the FLVCR1-related protein FLVCR2. Together, our results suggest that FY981 FeLV uses FLVCR1, FLVCR2, and THTR1 as receptors. Our findings suggest the possibility that pathogenic FeLV-C arises in FeLV-infected cats through intermediates that are multitropic in their receptor use.
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12
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Keel SB, Doty RT, Yang Z, Quigley JG, Chen J, Knoblaugh S, Kingsley PD, De Domenico I, Vaughn MB, Kaplan J, Palis J, Abkowitz JL. A Heme Export Protein Is Required for Red Blood Cell Differentiation and Iron Homeostasis. Science 2008; 319:825-8. [DOI: 10.1126/science.1151133] [Citation(s) in RCA: 288] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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13
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Brown JK, Fung C, Tailor CS. Comprehensive mapping of receptor-functioning domains in feline leukemia virus subgroup C receptor FLVCR1. J Virol 2006; 80:1742-51. [PMID: 16439531 PMCID: PMC1367145 DOI: 10.1128/jvi.80.4.1742-1751.2006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Infection of cells by the highly anemogenic feline leukemia virus subgroup C (FeLV-C) is mediated by the heme exporter FLVCR1, a cell surface protein containing 12 potential transmembrane segments with six presumptive extracellular loops (ECLs). To identify FLVCR1 residues critical for mediating FeLV-C infection, we first independently isolated a human cDNA encoding the FLVCR2 protein that shares 52% identity to human FLVCR1, and we show that FLVCR2 does not function as a receptor for FeLV-C. Then, by generating specific hybrids between FLVCR1 and FLVCR2 and testing susceptibility of mouse cells expressing these hybrids to beta-galactosidase encoding FeLV-C, we identify FLVCR1 ECLs 1 and 6 as critical for mediating FeLV-C infection. Mouse cells expressing a hybrid protein containing FLVCR2 backbone with the ECL6 sequence from FLVCR1 were highly susceptible to FeLV-C infection. Using site-directed mutagenesis, we show that a single mutation of Asn463 in FLVCR2 ECL6 to an acidic Asp residue (a residue present in the corresponding position 487 in FLVCR1 ECL6) is sufficient to render FLVCR2 functional as an FeLV-C receptor. However, an Asp487Asn mutation in FLVCR1 ECL6 or substitution of the entire FLVCR1 ECL6 sequence for FLVCR2 ECL6 sequence does not disrupt receptor function. Subsequent substitutions show that residues within FLVCR1 ECL1 also contribute to mediating FeLV-C infection. Furthermore, our results suggest that FLVCR1 regions that mediate FeLV-C surface unit binding are distinct from ECL1 and ECL6. Our results are consistent with previous conclusions that infection of cells by gammaretroviruses involves interaction of virus with multiple receptor regions.
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MESH Headings
- Amino Acid Sequence
- Amino Acid Substitution
- Animals
- Cell Line
- DNA/chemistry
- DNA/genetics
- DNA, Complementary/isolation & purification
- Genes, Reporter
- Humans
- Leukemia Virus, Feline/physiology
- Membrane Transport Proteins/chemistry
- Membrane Transport Proteins/genetics
- Membrane Transport Proteins/physiology
- Mice
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation, Missense
- Protein Structure, Tertiary
- Receptors, Virus/chemistry
- Receptors, Virus/genetics
- Receptors, Virus/physiology
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Recombination, Genetic
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- beta-Galactosidase/analysis
- beta-Galactosidase/genetics
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Affiliation(s)
- Jennifer K Brown
- The Hospital for Sick Children, Infection, Immunity, Injury Repair Program, 555 University Avenue, Toronto, ON M5G 1X8, Canada
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14
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Latunde-Dada GO, Simpson RJ, McKie AT. Recent advances in mammalian haem transport. Trends Biochem Sci 2006; 31:182-8. [PMID: 16487711 DOI: 10.1016/j.tibs.2006.01.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Revised: 01/04/2006] [Accepted: 01/30/2006] [Indexed: 12/12/2022]
Abstract
Haem is a structural component of numerous cellular proteins and contributes greatly to iron metabolic processes in mammals. Haem-carrier protein 1 (HCP1) has recently been cloned and characterized as a putative transporter in the apical region of the duodenum, and is responsible for uptake of haem into the gut cells. Its expression is regulated pre- and post-translationally in hypoxic and iron-deficient mice, respectively. The identification of HCP1 has revealed the long-sought mechanism by which haem--an important source of dietary iron--is absorbed from the diet by the gut. Feline leukaemic virus receptor (FLCVR) and ABC transporter ABCG2, characterized in haematopoietic cells, have also recently been shown to export haem, particularly under stress. FLVCR protects developing erythroid cells from haem toxicity during the early stages of differentiation, and ABCG2 averts protoporphyrin accumulation (particularly under hypoxic conditions). These haem-efflux proteins are expressed in other cells and tissues including the intestine where they might function as apical haem exporters to prevent toxicity in the enterocytes.
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Affiliation(s)
- Gladys O Latunde-Dada
- Department of Biochemistry and Nutrition Sciences Research Division, King's College London, Franklin Wilkin's Building, 150 Stamford Street, London SE1 9NH, UK
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15
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Quigley JG, Yang Z, Worthington MT, Phillips JD, Sabo KM, Sabath DE, Berg CL, Sassa S, Wood BL, Abkowitz JL. Identification of a human heme exporter that is essential for erythropoiesis. Cell 2004; 118:757-66. [PMID: 15369674 DOI: 10.1016/j.cell.2004.08.014] [Citation(s) in RCA: 296] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Revised: 07/22/2004] [Accepted: 07/27/2004] [Indexed: 01/11/2023]
Abstract
FLVCR, a member of the major facilitator superfamily of transporter proteins, is the cell surface receptor for feline leukemia virus, subgroup C. Retroviral interference with FLVCR display results in a loss of erythroid progenitors (colony-forming units-erythroid, CFU-E) and severe anemia in cats. In this report, we demonstrate that human FLVCR exports cytoplasmic heme and hypothesize that human FLVCR is required on developing erythroid cells to protect them from heme toxicity. Inhibition of FLVCR in K562 cells decreases heme export, impairs their erythroid maturation and leads to apoptosis. FLVCR is upregulated on CFU-E, indicating that heme export is important in primary cells at this stage. Studies of FLVCR expression in cell lines suggest this exporter also impacts heme trafficking in intestine and liver. To our knowledge, this is the first description of a mammalian heme transporter.
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Affiliation(s)
- John G Quigley
- Department of Medicine/Hematology, University of Washington, Seattle 98195, USA
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16
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Tailor CS, Lavillette D, Marin M, Kabat D. Cell surface receptors for gammaretroviruses. Curr Top Microbiol Immunol 2003; 281:29-106. [PMID: 12932075 DOI: 10.1007/978-3-642-19012-4_2] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Evidence obtained during the last few years has greatly extended our understanding of the cell surface receptors that mediate infections of retroviruses and has provided many surprising insights. In contrast to other cell surface components such as lectins or proteoglycans that influence infections indirectly by enhancing virus adsorption onto specific cells, the true receptors induce conformational changes in the viral envelope glycoproteins that are essential for infection. One surprise is that all of the cell surface receptors for gamma-retroviruses are proteins that have multiple transmembrane (TM) sequences, compatible with their identification in known instances as transporters for important solutes. In striking contrast, almost all other animal viruses use receptors that exclusively have single TM sequences, with the sole proven exception we know of being the coreceptors used by lentiviruses. This evidence strongly suggests that virus genera have been prevented because of their previous evolutionary adaptations from switching their specificities between single-TM and multi-TM receptors. This evidence also implies that gamma-retroviruses formed by divergent evolution from a common origin millions of years ago and that individual viruses have occasionally jumped between species (zoonoses) while retaining their commitment to using the orthologous receptor of the new host. Another surprise is that many gamma-retroviruses use not just one receptor but pairs of closely related receptors as alternatives. This appears to have enhanced viral survival by severely limiting the likelihood of host escape mutations. All of the receptors used by gamma-retroviruses contain hypervariable regions that are often heavily glycosylated and that control the viral host range properties, consistent with the idea that these sequences are battlegrounds of virus-host coevolution. However, in contrast to previous assumptions, we propose that gamma-retroviruses have become adapted to recognize conserved sites that are important for the receptor's natural function and that the hypervariable sequences have been elaborated by the hosts as defense bulwarks that surround the conserved viral attachment sites. Previously, it was believed that binding to receptors directly triggers a series of conformational changes in the viral envelope glycoproteins that culminate in fusion of the viral and cellular membranes. However, new evidence suggests that gamma-retroviral association with receptors triggers an obligatory interaction or cross-talk between envelope glycoproteins on the viral surface. If this intermediate step is prevented, infection fails. Conversely, in several circumstances this cross-talk can be induced in the absence of a cell surface receptor for the virus, in which case infection can proceed efficiently. This new evidence strongly implies that the role of cell surface receptors in infections of gamma-retroviruses (and perhaps of other enveloped animal viruses) is more complex and interesting than was previously imagined. Recently, another gammaretroviral receptor with multiple transmembrane sequences was cloned. See Prassolov, Y., Zhang, D., Ivanov, D., Lohler, J., Ross, S.R., and Stocking, C. Sodium-dependent myo-inositol transporter 1 is a receptor for Mus cervicolor M813 murine leukemia virus.
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Affiliation(s)
- C S Tailor
- Infection, Immunity Injury and Repair Program, Hospital for Sick Children, Toronto, ON M5G 1XB, Canada
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17
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Abstract
OBJECTIVES To examine clinical features, laboratory test results, treatment, and outcome of dogs with pure red cell aplasia (PRCA). DESIGN Retrospective study. ANIMALS 13 dogs with severe nonregenerative anemia and bone marrow erythroid aplasia. PROCEDURES Medical records of dogs determined to have PRCA on the basis of results of blood and bone marrow analysis between 1996 and 2000 were reviewed. Criteria for inclusion in the study were severe nonregenerative anemia (Hct < 20%; reticulocyte count < 1.0%), selective erythroid aplasia in bone marrow, and lack of underlying diseases that may have caused the anemia. RESULTS Median age of dogs was 6.5 years. Females were significantly overrepresented. Median Hct was 10%, and median reticulocyte count was 0.1%. Direct Coombs' test results were negative for all dogs tested, and spherocytosis was evident in 2 dogs. All dogs were treated with prednisolone, and 2 dogs were treated with prednisolone and cyclophosphamide. Responses to treatment were complete, partial, and poor in 10, 1, and 2 dogs, respectively. Median time required to achieve an increase of 5% or more in Hct was 38 days, and median time to complete remission was 118 days. Of 10 dogs for which follow-up information was available, only 1 required long-term immunosuppressive treatment. CONCLUSIONS AND CLINICAL RELEVANCE Dogs with PRCA appear to respond readily to treatment with immunosuppressive drugs; however, hematologic responses may not be observed for weeks to months after initiation of treatment.
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Affiliation(s)
- Douglas J Weiss
- Department of Veterinary PathoBiology, College of Veterinary Medicine, University of Minnesota, St Paul 55108, USA
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18
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Cloning of the cellular receptor for feline leukemia virus subgroup C (FeLV-C), a retrovirus that induces red cell aplasia. Blood 2000. [DOI: 10.1182/blood.v95.3.1093.003k01_1093_1099] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Feline leukemia virus-C (FeLV-C) causes red cell aplasia in cats, likely through its interaction with its cell surface receptor. We identified this receptor by the functional screening of a library of complementary DNAs (cDNA) from feline T cells. The library, which was cloned into a retroviral vector, was introduced into FeLV-C–resistant murine (NIH 3T3) cells. The gene conferring susceptibility to FeLV-C was isolated and reintroduced into the same cell type, as well as into FeLV-C–resistant rat (NRK 52E) cells, to verify its role in viral infection. The receptor cDNA is predicted to encode a protein of 560 amino acids with 12 membrane-spanning domains, termed FLVCR. FLVCR has significant amino acid sequence homology with members of the major facilitator superfamily and especially D-glucarate transporters described in bacteria and in C. elegans. As FeLV-C impairs the in vivo differentiation of burst-forming unit–erythroid to colony-forming unit–erythroid, we hypothesize that this transporter system could have an essential role in early erythropoiesis. In further studies, a 6-kb fragment of the human FLVCR gene was amplified by polymerase chain reaction from genomic DNA, using homologous cDNA sequences identified in the human Expressed Sequence Tags database. By radiation hybrid mapping, the human gene was localized to a 0.5-centiMorgan region on the long arm of chromosome 1 at q31.3.
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19
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Tailor CS, Willett BJ, Kabat D. A putative cell surface receptor for anemia-inducing feline leukemia virus subgroup C is a member of a transporter superfamily. J Virol 1999; 73:6500-5. [PMID: 10400745 PMCID: PMC112732 DOI: 10.1128/jvi.73.8.6500-6505.1999] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Domestic cats infected with the horizontally transmitted feline leukemia virus subgroup A (FeLV-A) often produce mutants (termed FeLV-C) that bind to a distinct cell surface receptor and cause severe aplastic anemia in vivo and erythroblast destruction in bone marrow cultures. The major determinant for FeLV-C-induced anemia has been mapped to a small region of the surface envelope glycoprotein that is responsible for its receptor binding specificity. Thus, erythroblast destruction may directly or indirectly result from FeLV-C binding to its receptor. To address these issues, we functionally cloned a putative cell surface receptor for FeLV-C (FLVCR) by using a human T-lymphocyte cDNA library in a retroviral vector. Expression of the 2.0-kbp FLVCR cDNA in naturally resistant Swiss mouse fibroblasts and Chinese hamster ovary cells caused substantial susceptibility to FeLV-C but no change in susceptibilities to FeLV-B and other retroviruses. The predicted FLVCR protein contains 555 amino acids and 12 hydrophobic potential membrane-spanning sequences. Database searches indicated that FLVCR is a member of the major-facilitator superfamily of transporters and implied that it may transport an organic anion. RNA blot analyses showed that FLVCR mRNA is expressed in multiple hematopoietic lineages rather than specifically in erythroblasts. These results suggest that the targeted destruction of erythroblasts by FeLV-C may derive from their greater sensitivity to this virus rather than from a preferential susceptibility to infection.
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Affiliation(s)
- C S Tailor
- Department of Biochemistry and Molecular Biology, Oregon Health Sciences University, Portland, Oregon 97201-3098, USA.
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20
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Rojko JL, Hartke JR, Cheney CM, Phipps AJ, Neil JC. Cytopathic feline leukemia viruses cause apoptosis in hemolymphatic cells. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1996; 16:13-43. [PMID: 8822790 DOI: 10.1007/978-3-642-79850-4_2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Certain isolates of the oncoretrovirus feline leukemia virus (FeLV) are strongly cytopathic for hemolymphatic cells. A major cytopathicity determinant is encoded by the SU envelope glucoprotein gp70. Isolates with subgroup C SU gp70 genes specifically induce apoptosis in hemolymphatic cells but not fibroblasts. In vitro exposure of feline T-cells to FeLV-C leads first to productive viral replication, next to virus-induced cell agglutination, and lastly to apogenesis. This in vitro phenomenon may explain the severe progressive thymic atrophy and erythroid aplasia which follow viremic FeLV-C infection in vivo. Inappropriate apoptosis induction has also been hypothesized to explain the severe thymico-lymphoid atrophy and progressive immune deterioration associated with isolates of FeLV containing variant envelope genes. The influence of envelope hypervariability (variable regions 1 [Vr1] and 5 [Vr5] on virus tropism, viremia induction, neutralizing antibody development and cytopathicity is discussed. Certain potentially cytopathic elements in FeLV SU gp70 Vr5 may derive from replication-defective, poorly expressed, endogenous FeLVs. Other more highly conserved regions in FeLV TM envelope p15E may also influence apoptosis induction.
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Affiliation(s)
- J L Rojko
- Department of Veterinary Pathobiology, Ohio State University, Columbus 43210, USA
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21
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Linenberger ML, Abkowitz JL. Haematological disorders associated with feline retrovirus infections. BAILLIERE'S CLINICAL HAEMATOLOGY 1995; 8:73-112. [PMID: 7663052 PMCID: PMC7135792 DOI: 10.1016/s0950-3536(05)80233-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Feline oncornavirus and lentivirus infections have provided useful models to characterize the virus and host cell factors involved in a variety of marrow suppressive disorders and haematological malignancies. Exciting recent progress has been made in the characterization of the viral genotypic features involved in FeLV-associated diseases. Molecular studies have clearly defined the causal role of variant FeLV env gene determinants in two disorders: the T-lymphocyte cytopathicity and the clinical acute immunosuppression induced by the FeLV-FAIDS variant and the pure red cell aplasia induced by FeLV-C/Sarma. Variant or enFeLV env sequences also appear to play a role in FeLV-associated lymphomas. Additional studies are required to determine the host cell processes that are perturbed by these variant env gene products. In the case of the FeLV-FAIDS variant, the aberrant env gene products appear to impair superinfection interference, resulting in accumulation of unintegrated viral DNA and cell death. In other cases it is likely that the viral env proteins interact with host products that are important in cell viability and/or proliferation. Understanding of these mechanisms will therefore provide insights to factors involved in normal lymphohaematopoiesis. Similarly, studies of FeLV-induced haematological neoplasms should reveal recombination or rearrangement events involving as yet unidentified host gene sequences that encode products involved in normal cell growth regulation. These sequences may include novel protoncogenes or sequences homologous to genes implicated in human haematological malignancies. The haematological consequences of FIV are quite similar to those associated with HIV. As with HIV, FIV does not appear to directly infect myeloid or erythroid precursors, and the mechanisms of marrow suppression likely involve virus, viral antigen, and/or infected accessory cells in the marrow microenvironment. Studies using in vitro experimental models are required to define the effects of each of these microenvironmental elements on haematopoietic progenitors. As little is known about the molecular mechanisms of FIV pathogenesis, additional studies of disease-inducing FIV strains are needed to identify the genotypic features that correlate with virulent phenotypic features. Finally, experimental FIV infection in cats provides the opportunity to correlate in vivo virological and haematological changes with in vitro observations in a large animal model that closely mimics HIV infection in man.
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MESH Headings
- Animals
- Antibodies, Viral/biosynthesis
- Antibodies, Viral/immunology
- Bone Marrow/pathology
- Bone Marrow/virology
- Cats/virology
- Feline Acquired Immunodeficiency Syndrome/immunology
- Feline Acquired Immunodeficiency Syndrome/transmission
- Genes, Viral
- Immunity, Cellular
- Immunodeficiency Virus, Feline/genetics
- Immunodeficiency Virus, Feline/immunology
- Immunodeficiency Virus, Feline/physiology
- Leukemia Virus, Feline/classification
- Leukemia Virus, Feline/genetics
- Leukemia Virus, Feline/immunology
- Leukemia Virus, Feline/physiology
- Leukemia, Feline/immunology
- Leukemia, Feline/transmission
- Lymphoma/epidemiology
- Lymphoma/veterinary
- Lymphoma/virology
- Myelodysplastic Syndromes/veterinary
- Myelodysplastic Syndromes/virology
- Red-Cell Aplasia, Pure/veterinary
- Red-Cell Aplasia, Pure/virology
- Retroviridae/classification
- Retroviridae Proteins/genetics
- Retroviridae Proteins/physiology
- Spumavirus/pathogenicity
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Affiliation(s)
- M L Linenberger
- Department of Medicine, University of Washington, Seattle 98195, USA
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22
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Brojatsch J, Kristal BS, Viglianti GA, Khiroya R, Hoover EA, Mullins JI. Feline leukemia virus subgroup C phenotype evolves through distinct alterations near the N terminus of the envelope surface glycoprotein. Proc Natl Acad Sci U S A 1992; 89:8457-61. [PMID: 1326757 PMCID: PMC49939 DOI: 10.1073/pnas.89.18.8457] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Feline leukemia viruses (FeLVs) belonging to the C subgroup induce aplastic anemia in domestic cats and have the ability, unique among FeLV strains, to proliferate in guinea pig fibroblasts in tissue culture. Previous studies have shown that the pathogenic and host range specificity of a prototype molecular clone of FeLV-C [FeLV-Sarma-C (FSC)] colocalize to a region encoding the 3' 73 amino acids of the pol gene product and the N-terminal 241 amino acids of the envelope surface glycoprotein named SU. Here, we amplified, via PCR, cloned, and sequenced the SU coding sequence from three additional anemia-inducing subgroup C FeLV isolates. Chimeric viruses were constructed by replacement of fragments of FeLV-C envelope genes into the FeLV-A prototype virus 61E. Using a modified vesicular stomatitis virus-FeLV pseudotype assay, we demonstrated that the subgroup C receptor specificity for each virus was determined by changes within the N-terminal 87-92 amino acids of SU, in which most changes occurred within the 15- to 20-amino-acid first variable region (V1). Determinants for growth in guinea pig cells colocalized to this region. Despite the consistent localization of biological determinants, the only consistent features that distinguished the deduced FeLV-A and FeLV-C proteins was one lysine-to-arginine change and a structural prediction of an alpha-helix in FeLV-A proteins versus random coil in FeLV-C proteins within V1. However, arginine in equilibrium with lysine substitutions were not sufficient to convert the subgroup A virus to the subgroup C phenotype or vice versa. Thus, certain distinct structural changes within the N-terminal region of FeLV SU can result in convergent viral phenotypes.
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Affiliation(s)
- J Brojatsch
- Department of Microbiology and Immunology, Stanford University School of Medicine, CA 94305-5402
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23
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Dean GA, Groshek PM, Mullins JI, Hoover EA. Hematopoietic target cells of anemogenic subgroup C versus nonanemogenic subgroup A feline leukemia virus. J Virol 1992; 66:5561-8. [PMID: 1323710 PMCID: PMC289115 DOI: 10.1128/jvi.66.9.5561-5568.1992] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Feline leukemia viruses (FeLVs) belonging to interference subgroup C induce fatal anemia resembling human pure red cell aplasia (PRCA). Subgroup A FeLVs, although closely related genetically to FeLVs of subgroup C, do not induce PRCA. The determinants for PRCA induction by a molecularly cloned prototype subgroup C virus (FeLV-Sarma-C [FSC]) have been localized to the N-terminal 241 amino acids of the surface glycoprotein (SU) gp70. To investigate whether the anemogenic activity of FSC reflects a unique capacity to infect erythroid progenitor cells, we used correlative immunogold, immunofluorescence, and cytological staining to study prospectively the hemopoietic cell populations infected by either FSC or FeLV-FAIDS-61E-A (F6A), a prototype of subgroup A virus. The results demonstrated that although only FSC-infected animals developed erythrocyte aplasia, the env SU and the major core protein (p27) were expressed in a surprisingly large fraction of the lymphoid, erythroid, and myeloid lineage marrow cells in both FSC- and F6A-infected cats. Between days 8 and 17 postinoculation, gp70 and p27 were detected in 43 to 73% of erythroid, 25 to 75% of lymphoid, and 35 to 50% of myeloid lineage cells, regardless of whether the cats were infected with FSC or F6A. Thus, anemogenic subgroup C and nonanemogenic subgroup A FeLVs have similar hemopoietic cell tropism and infection kinetics, despite their divergent effects on erythroid progenitor cell function. Acute anemia induction by subgroup C FeLV, therefore, does not reflect a unique tropism for marrow erythroid cells but rather indicates a unique cytopathic effect of the SU on erythroid progenitor cells.
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Affiliation(s)
- G A Dean
- Department of Pathology, Colorado State University, Fort Collins 80523
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24
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Abstract
Many agents are associated with bone marrow failure, including toxins, inherited metabolic defects, ionizing radiation, and viral infection. In most cases, the etiologic agent is unknown. Many of these unclassified cases have symptomatic, immunologic, or epidemiologic similarities to viral infections. Viruses from different taxonomic families have been implicated in bone marrow failure syndromes, and they appear to cause hematosuppression by a variety of mechanisms. Some of the viruses involved in relatively well characterized suppressive interactions will be reviewed, including parovovirus B19, dengue, hepatitis viruses, Epstein-Barr virus, cytomegalovirus and the human immunodeficiency virus.
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Affiliation(s)
- S J Rosenfeld
- Biology Section, National Heart, Lung and Blood Institute, Bethesda, Maryland 20892
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25
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Neil JC, Fulton R, Rigby M, Stewart M. Feline leukaemia virus: generation of pathogenic and oncogenic variants. Curr Top Microbiol Immunol 1991; 171:67-93. [PMID: 1667630 DOI: 10.1007/978-3-642-76524-7_4] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
MESH Headings
- Amino Acid Sequence
- Anemia/microbiology
- Anemia/veterinary
- Animals
- Base Sequence
- Cat Diseases/microbiology
- Cats/microbiology
- Feline Acquired Immunodeficiency Syndrome/microbiology
- Gene Expression Regulation, Neoplastic
- Gene Expression Regulation, Viral
- Gene Products, env/genetics
- Gene Products, env/physiology
- Genes, env
- Leukemia Virus, Feline/classification
- Leukemia Virus, Feline/genetics
- Leukemia Virus, Feline/pathogenicity
- Leukemia Virus, Feline/physiology
- Leukemia, Feline/microbiology
- Mink Cell Focus-Inducing Viruses/genetics
- Molecular Sequence Data
- Mutagenesis, Insertional
- Oncogenes
- Proto-Oncogenes
- Recombination, Genetic
- Repetitive Sequences, Nucleic Acid
- Transduction, Genetic
- Virulence
- Virus Integration
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Affiliation(s)
- J C Neil
- Beatson Institute for Cancer Research, Glasgow, UK
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26
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Abstract
Some generalizations can be drawn from a review of virus-associated bone marrow failure. The story of B19 parvovirus illustrates that viral infection may be an occult cause of marrow failure. Although the epidemiology of transient aplastic crisis suggested a viral aetiology, the implication of a single virus was surprising; the sporadic appearance of chronic bone marrow failure in immunosuppressed persons has had none of the features of a viral illness. The incrimination of parvovirus in these cases required development of specific immunological and molecular assays. Human and animal retrovirus studies have shown that small changes in the virus genome can have dramatic effects on the biology of the infectious agent and its pathogenicity in infected hosts. In Epstein-Barr virus infection, the host's immune response may play a more important role in mediating disease than virus cytotoxicity. Finally, the association of aplastic anaemia with hepatitis may be underestimated because of the inability to diagnose virus infection without obvious liver disease. The true spectrum of bone marrow disease due to virus infection is not known.
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