1
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Tarlinton R, Greenwood AD. Koala retrovirus and neoplasia: correlation and underlying mechanisms. Curr Opin Virol 2024; 67:101427. [PMID: 39047314 DOI: 10.1016/j.coviro.2024.101427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 07/03/2024] [Accepted: 07/05/2024] [Indexed: 07/27/2024]
Abstract
The koala retrovirus, KoRV, is one of the few models for understanding the health consequences of retroviral colonization of the germline. Such colonization events transition exogenous infectious retroviruses to Mendelian traits or endogenous retroviruses (ERVs). KoRV is currently in a transitional state from exogenous retrovirus to ERV, which in koalas (Phascolarctos cinereus) has been associated with strongly elevated levels of neoplasia. In this review, we describe what is currently known about the associations and underlying mechanisms of KoRV-induced neoplasia.
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Affiliation(s)
- Rachael Tarlinton
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, UK
| | - Alex D Greenwood
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany; School of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
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2
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Hayward JA, Tian S, Tachedjian G. GALV-KoRV-related retroviruses in diverse Australian and African rodent species. Virus Evol 2024; 10:veae061. [PMID: 39175839 PMCID: PMC11341202 DOI: 10.1093/ve/veae061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 06/12/2024] [Accepted: 07/26/2024] [Indexed: 08/24/2024] Open
Abstract
The enigmatic origins and transmission events of the gibbon ape leukemia virus (GALV) and its close relative the koala retrovirus (KoRV) have been a source of enduring debate. Bats and rodents are each proposed as major reservoirs of interspecies transmission, with ongoing efforts to identify additional animal hosts of GALV-KoRV-related retroviruses. In this study, we identified nine rodent species as novel hosts of GALV-KoRV-related retroviruses. Included among these hosts are two African rodents, revealing the first appearance of this clade beyond the Australian and Southeast Asian region. One of these African rodents, Mastomys natalensis, carries an endogenous GALV-KoRV-related retrovirus that is fully intact and potentially still infectious. Our findings support the hypothesis that rodents are the major carriers of GALV-KoRV-related retroviruses.
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Affiliation(s)
- Joshua A Hayward
- Life Sciences Discipline, Burnet Institute, 85 Commercial Rd, Melbourne, VIC 3004, Australia
- Department of Microbiology, Monash University, Wellington Rd, Clayton, VIC 3168, Australia
| | - Shuoshuo Tian
- Life Sciences Discipline, Burnet Institute, 85 Commercial Rd, Melbourne, VIC 3004, Australia
| | - Gilda Tachedjian
- Life Sciences Discipline, Burnet Institute, 85 Commercial Rd, Melbourne, VIC 3004, Australia
- Department of Microbiology, Monash University, Wellington Rd, Clayton, VIC 3168, Australia
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, 792 Elizabeth St, Melbourne, VIC 3000, Australia
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3
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Mottaghinia S, Stenzel S, Tsangaras K, Nikolaidis N, Laue M, Müller K, Hölscher H, Löber U, McEwen GK, Donnellan SC, Rowe KC, Aplin KP, Goffinet C, Greenwood AD. A recent gibbon ape leukemia virus germline integration in a rodent from New Guinea. Proc Natl Acad Sci U S A 2024; 121:e2220392121. [PMID: 38305758 PMCID: PMC10861895 DOI: 10.1073/pnas.2220392121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 11/30/2023] [Indexed: 02/03/2024] Open
Abstract
Germline colonization by retroviruses results in the formation of endogenous retroviruses (ERVs). Most colonization's occurred millions of years ago. However, in the Australo-Papuan region (Australia and New Guinea), several recent germline colonization events have been discovered. The Wallace Line separates much of Southeast Asia from the Australo-Papuan region restricting faunal and pathogen dispersion. West of the Wallace Line, gibbon ape leukemia viruses (GALVs) have been isolated from captive gibbons. Two microbat species from China appear to have been infected naturally. East of Wallace's Line, the woolly monkey virus (a GALV) and the closely related koala retrovirus (KoRV) have been detected in eutherians and marsupials in the Australo-Papuan region, often vertically transmitted. The detected vertically transmitted GALV-like viruses in Australo-Papuan fauna compared to sporadic horizontal transmission in Southeast Asia and China suggest the GALV-KoRV clade originates in the former region and further models of early-stage genome colonization may be found. We screened 278 samples, seven bat and one rodent family endemic to the Australo-Papuan region and bat and rodent species found on both sides of the Wallace Line. We identified two rodents (Melomys) from Australia and Papua New Guinea and no bat species harboring GALV-like retroviruses. Melomys leucogaster from New Guinea harbored a genomically complete replication-competent retrovirus with a shared integration site among individuals. The integration was only present in some individuals of the species indicating this retrovirus is at the earliest stages of germline colonization of the Melomys genome, providing a new small wild mammal model of early-stage genome colonization.
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Affiliation(s)
- Saba Mottaghinia
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin10315, Germany
- Centre International de Recherche en Infectiologie, Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, École Nationale Supérieure de Lyon, LyonF-69007, France
| | - Saskia Stenzel
- Institute of Virology Charité–Universitätsmedizin Berlin, BerlinD-10117, Germany
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
| | - Kyriakos Tsangaras
- Department of Life and Health Sciences, University of Nicosia, NicosiaCY-2417, Cyprus
| | - Nikolas Nikolaidis
- Department of Biological Science, Center for Applied Biotechnology Studies, and Center for Computational and Applied Mathematics, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA92834-6850
| | - Michael Laue
- Advanced Light and Electron Microscopy (ZBS 4), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, BerlinD-13353, Germany
| | - Karin Müller
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin10315, Germany
| | - Henriette Hölscher
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin10315, Germany
| | - Ulrike Löber
- Max-Delbrük Center for Molecular Medicine Helmholtz Association, Berlin13125, Germany
| | - Gayle K. McEwen
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin10315, Germany
| | | | - Kevin C. Rowe
- Sciences Department, Museums Victoria, Melbourne, VIC3001, Australia
| | - Ken P. Aplin
- South Australian Museum, North Terrace, Adelaide SA5000, Australia
| | - Christine Goffinet
- Institute of Virology Charité–Universitätsmedizin Berlin, BerlinD-10117, Germany
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, LiverpoolL3 5QA, United Kingdom
| | - Alex D. Greenwood
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin10315, Germany
- School of Veterinary Medicine, Freie Universität Berlin, Berlin14163, Germany
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4
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Jern P, Greenwood AD. Wildlife endogenous retroviruses: colonization, consequences, and cooption. Trends Genet 2024; 40:149-159. [PMID: 37985317 DOI: 10.1016/j.tig.2023.10.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/24/2023] [Accepted: 10/31/2023] [Indexed: 11/22/2023]
Abstract
Endogenous retroviruses (ERVs) are inherited genomic remains of past germline retroviral infections. Research on human ERVs has focused on medical implications of their dysregulation on various diseases. However, recent studies incorporating wildlife are yielding remarkable perspectives on long-term retrovirus-host interactions. These initial forays into broader taxonomic analysis, including sequencing of multiple individuals per species, show the incredible plasticity and variation of ERVs within and among wildlife species. This demonstrates that stochastic processes govern much of the vertebrate genome. In this review, we elaborate on discoveries pertaining to wildlife ERV origins and evolution, genome colonization, and consequences for host biology.
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Affiliation(s)
- Patric Jern
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
| | - Alex D Greenwood
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany; School of Veterinary Medicine, Freie Unversität Berlin, Berlin, Germany.
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5
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Denner J. Vaccination against the Koala Retrovirus (KoRV): Problems and Strategies. Animals (Basel) 2021; 11:ani11123555. [PMID: 34944329 PMCID: PMC8697897 DOI: 10.3390/ani11123555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 12/03/2021] [Accepted: 12/09/2021] [Indexed: 02/07/2023] Open
Abstract
The koala retrovirus (KoRV) is spreading in the koala population from the north to the south of Australia and is also in the process of endogenization into the koala genome. Virus infection is associated with tumorigenesis and immunodeficiency and is contributing to the decline of the animal population. Antibody production is an excellent marker of retrovirus infection; however, animals carrying endogenous KoRV are tolerant. Therefore, the therapeutic immunization of animals carrying endogenous KoRV seems to be ineffective. Using the recombinant transmembrane (TM) envelope protein of the KoRV, we immunized goats, rats and mice, obtaining in all cases neutralizing antibodies which recognize epitopes in the fusion peptide proximal region (FPPR), and in the membrane-proximal external region (MPER). Immunizing several animal species with the corresponding TM envelope protein of the closely related porcine endogenous retrovirus (PERV), as well as the feline leukemia virus (FeLV), we also induced neutralizing antibodies with similar epitopes. Immunizing with the TM envelope protein in addition to the surface envelope proteins of all three viruses resulted in higher titers of neutralizing antibodies. Immunizing KoRV-negative koalas with our vaccine (which is composed of both envelope proteins) may protect these animals from infection, and these may be the starting points of a virus-free population.
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Affiliation(s)
- Joachim Denner
- Institute of Virology, Free University Berlin, Robert von Ostertag-Str. 7-13, 14163 Berlin, Germany
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Abstract
Bats are infamous reservoirs of deadly human viruses. While retroviruses, such as the human immunodeficiency virus (HIV), are among the most significant of virus families that have jumped from animals into humans, whether bat retroviruses have the potential to infect and cause disease in humans remains unknown. Recent reports of retroviruses circulating in bat populations builds on two decades of research describing the fossil records of retroviral sequences in bat genomes and of viral metagenomes extracted from bat samples. The impact of the global COVID-19 pandemic demands that we pay closer attention to viruses hosted by bats and their potential as a zoonotic threat. Here we review current knowledge of bat retroviruses and explore the question of whether they represent a threat to humans.
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Affiliation(s)
- Joshua A. Hayward
- Health Security Program, Life Sciences Discipline, Burnet Institute, Melbourne, VIC, Australia
- Department of Microbiology, Monash University, Clayton, VIC, Australia
| | - Gilda Tachedjian
- Health Security Program, Life Sciences Discipline, Burnet Institute, Melbourne, VIC, Australia
- Department of Microbiology, Monash University, Clayton, VIC, Australia
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC, Australia
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7
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Kayesh MEH, Hashem MA, Tsukiyama-Kohara K. Toll-Like Receptor and Cytokine Responses to Infection with Endogenous and Exogenous Koala Retrovirus, and Vaccination as a Control Strategy. Curr Issues Mol Biol 2021; 43:52-64. [PMID: 33946297 PMCID: PMC8928999 DOI: 10.3390/cimb43010005] [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: 03/29/2021] [Revised: 04/28/2021] [Accepted: 04/28/2021] [Indexed: 02/07/2023] Open
Abstract
Koala populations are currently declining and under threat from koala retrovirus (KoRV) infection both in the wild and in captivity. KoRV is assumed to cause immunosuppression and neoplastic diseases, favoring chlamydiosis in koalas. Currently, 10 KoRV subtypes have been identified, including an endogenous subtype (KoRV-A) and nine exogenous subtypes (KoRV-B to KoRV-J). The host’s immune response acts as a safeguard against pathogens. Therefore, a proper understanding of the immune response mechanisms against infection is of great importance for the host’s survival, as well as for the development of therapeutic and prophylactic interventions. A vaccine is an important protective as well as being a therapeutic tool against infectious disease, and several studies have shown promise for the development of an effective vaccine against KoRV. Moreover, CRISPR/Cas9-based genome editing has opened a new window for gene therapy, and it appears to be a potential therapeutic tool in many viral infections, which could also be investigated for the treatment of KoRV infection. Here, we discuss the recent advances made in the understanding of the immune response in KoRV infection, as well as the progress towards vaccine development against KoRV infection in koalas.
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Affiliation(s)
- Mohammad Enamul Hoque Kayesh
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan; (M.E.H.K.); (M.A.H.)
- Department of Microbiology and Public Health, Faculty of Animal Science and Veterinary Medicine, Patuakhali Science and Technology University, Barishal 8210, Bangladesh
| | - Md Abul Hashem
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan; (M.E.H.K.); (M.A.H.)
- Department of Health, Chattogram City Corporation, Chattogram 4000, Bangladesh
- Laboratory of Animal Hygiene, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan
| | - Kyoko Tsukiyama-Kohara
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan; (M.E.H.K.); (M.A.H.)
- Laboratory of Animal Hygiene, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan
- Correspondence: ; Tel.: +81-99-285-3589
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8
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Hashem MA, Kayesh MEH, Maetani F, Eiei T, Mochizuki K, Ochiai S, Ito A, Ito N, Sakurai H, Asai T, Tsukiyama-Kohara K. Koala retrovirus (KoRV) subtypes and their impact on captive koala (Phascolarctos cinereus) health. Arch Virol 2021; 166:1893-1901. [PMID: 33900468 DOI: 10.1007/s00705-021-05078-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Accepted: 03/07/2021] [Indexed: 01/20/2023]
Abstract
Koala retrovirus (KoRV), a major pathogen of koalas, exists in both endogenous (KoRV-A) and exogenous forms (KoRV-B to J). However, the impact of infection with multiple subtypes is not well understood. Accordingly, in this study, we surveyed a representative sample from a Japanese zoo population to determine the infection status for three KoRV subtypes (KoRV-A, B, and C) and to investigate the proviral and RNA load profiles in animals with single- and multiple-subtype infections, using peripheral blood mononuclear cells (PBMCs) and plasma. Six koalas were evaluated in the study; all were infected with KoRV-A, and two koalas were coinfected with non-A subtypes (KoRV-B and/or KoRV-C). The highest KoRV total RNA and viral loads in PBMCs and plasma were found in a koala infected with multiple subtypes (KoRV-A, -B and -C). The other koala infected with multiple subtypes (KoRV-A and B) showed the highest proviral PBMC load but the lowest RNA copy number in PBMC and plasma. PBMCs from this animal were cultured for further investigation, and KoRV RNA was detected in the cells and culture supernatant after 7 and/or 14 days. The koalas harboring multiple subtypes had a higher white blood cell count than those harboring only KoRV-A and were judged to be leukemic, and they subsequently died due to lymphoma. Accordingly, we conclude that coinfection with multiple KoRV subtypes may be linked to more-severe disease. In a sequence alignment, the detected KoRV-A env gene showed 100% sequence identity to the reference gene, whereas the KoRV-B and -C env genes varied from their reference sequences.
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Affiliation(s)
- Md Abul Hashem
- Transboundary Animal Diseases Center, Laboratory of Animal Hygiene, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan.,Laboratory of Animal Hygiene, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan.,Department of Health, Chattogram City Corporation, Chattogram, 4000, Bangladesh
| | - Mohammad Enamul Hoque Kayesh
- Transboundary Animal Diseases Center, Laboratory of Animal Hygiene, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan.,Laboratory of Animal Hygiene, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan.,Department of Microbiology and Public Health, Patuakhali Science and Technology University, Babugonj, Barishal, 8210, Bangladesh
| | - Fumie Maetani
- Hirakawa Zoological Park, Kagoshima, 891-0133, Japan
| | - Taiki Eiei
- Hirakawa Zoological Park, Kagoshima, 891-0133, Japan
| | | | | | - Ayaka Ito
- Hirakawa Zoological Park, Kagoshima, 891-0133, Japan
| | - Nanao Ito
- Hirakawa Zoological Park, Kagoshima, 891-0133, Japan
| | | | - Takayuki Asai
- Hirakawa Zoological Park, Kagoshima, 891-0133, Japan
| | - Kyoko Tsukiyama-Kohara
- Transboundary Animal Diseases Center, Laboratory of Animal Hygiene, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan. .,Laboratory of Animal Hygiene, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan.
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9
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Quigley BL, Wedrowicz F, Hogan F, Timms P. Phylogenetic and geographical analysis of a retrovirus during the early stages of endogenous adaptation and exogenous spread in a new host. Mol Ecol 2020; 30:2626-2640. [PMID: 33219558 PMCID: PMC8246579 DOI: 10.1111/mec.15735] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 10/14/2020] [Accepted: 11/06/2020] [Indexed: 12/26/2022]
Abstract
Most retroviral endogenization and host adaptation happened in the distant past, with the opportunity to study these processes as they occurred lost to time. An exception exists with the discovery that koala retrovirus (KoRV) has recently begun its endogenization into the koala (Phascolarctos cinereus) genome. What makes this opportunity remarkable is the fact that Northern Australian koalas appear to be undergoing endogenization with one KoRV subtype (KoRV‐A), while all subtypes (KoRV‐A‐I) coexist exogenously, and Southern Australian koalas appear to carry all KoRV subtypes as an exogenous virus. To understand the distribution and relationship of all KoRV variants in koalas, the proviral KoRV envelope gene receptor binding domain was assessed across the koala's natural range. Examination of KoRV subtype‐specific proviral copy numbers per cell found that KoRV‐A proviral integration levels were consistent with endogenous incorporation in Northern Australia (southeast Queensland and northeast New South Wales) while revealing lower levels of KoRV‐A proviral integration (suggestive of exogenous incorporation) in southern regions (southeast New South Wales and Victoria). Phylogeographical analysis indicated that several major KoRV‐A variants were distributed uniformly across the country, while non‐KoRV‐A variants appeared to have undergone lineage diversification in geographically distinct regions. Further analysis of the major KoRV‐A variants revealed a distinct shift in variant proportions in southeast New South Wales, suggesting this as the geographical region where KoRV‐A transitions from being predominantly endogenous to exogenous in Australian koalas. Collectively, these findings advance both our understanding of KoRV in koalas and of retroviral endogenization and diversification in general. see also the Perspective by Elliott S. Chiu and Roderick B. Gagne.
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Affiliation(s)
- Bonnie L Quigley
- Genecology Research Centre, University of the Sunshine Coast, Sippy Downs, QLD, Australia
| | - Faye Wedrowicz
- School of Science, Psychology and Sport, Federation University Australia, Churchill, Vic., Australia
| | - Fiona Hogan
- School of Science, Psychology and Sport, Federation University Australia, Churchill, Vic., Australia
| | - Peter Timms
- Genecology Research Centre, University of the Sunshine Coast, Sippy Downs, QLD, Australia
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10
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Kayesh MEH, Hashem MA, Maetani F, Eiei T, Mochizuki K, Ochiai S, Ito A, Ito N, Sakurai H, Asai T, Tsukiyama-Kohara K. CD4, CD8b, and Cytokines Expression Profiles in Peripheral Blood Mononuclear Cells Infected with Different Subtypes of KoRV from Koalas ( Phascolarctos cinereus) in a Japanese Zoo. Viruses 2020; 12:v12121415. [PMID: 33316950 PMCID: PMC7764738 DOI: 10.3390/v12121415] [Citation(s) in RCA: 6] [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: 11/19/2020] [Revised: 12/06/2020] [Accepted: 12/07/2020] [Indexed: 12/13/2022] Open
Abstract
Koala retrovirus (KoRV) poses a major threat to koala health and conservation, and currently has 10 identified subtypes: an endogenous subtype (KoRV-A) and nine exogenous subtypes (KoRV-B to KoRV-J). However, subtype-related variations in koala immune response to KoRV are uncharacterized. In this study, we investigated KoRV-related immunophenotypic changes in a captive koala population (Hirakawa zoo, Japan) with a range of subtype infection profiles (KoRV-A only vs. KoRV-A with KoRV-B and/or -C), based on qPCR measurements of CD4, CD8b, IL-6, IL-10 and IL-17A mRNA expression in unstimulated and concanavalin (Con)-A-stimulated peripheral blood mononuclear cells (PBMCs). Although CD4, CD8b, and IL-17A expression did not differ between KoRV subtype infection profiles, IL-6 expression was higher in koalas with exogenous infections (both KoRV-B and KoRV-C) than those with the endogenous subtype only. IL-10 expression did not significantly differ between subtype infection profiles but did show a marked increase—accompanying decreased CD4:CD8b ratio—in a koala with lymphoma and co-infected with KoRV-A and -B, thus suggesting immunosuppression. Taken together, the findings of this study provide insights into koala immune response to multiple KoRV subtypes, which can be exploited for the development of prophylactic and therapeutic interventions for this iconic marsupial species.
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Affiliation(s)
- Mohammad Enamul Hoque Kayesh
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan; (M.E.H.K.); (M.A.H.)
- Department of Microbiology and Public Health, Faculty of Animal Science and Veterinary Medicine, Patuakhali Science and Technology University, Barishal 8210, Bangladesh
| | - Md Abul Hashem
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan; (M.E.H.K.); (M.A.H.)
- Department of Health, Chattogram City Corporation, Chattogram 4000, Bangladesh
| | - Fumie Maetani
- Hirakawa Zoological Park, Kagoshima 891-0133, Japan; (F.M.); (T.E.); (K.M.); (S.O.); (A.I.); (N.I.); (H.S.); (T.A.)
| | - Taiki Eiei
- Hirakawa Zoological Park, Kagoshima 891-0133, Japan; (F.M.); (T.E.); (K.M.); (S.O.); (A.I.); (N.I.); (H.S.); (T.A.)
| | - Kyoya Mochizuki
- Hirakawa Zoological Park, Kagoshima 891-0133, Japan; (F.M.); (T.E.); (K.M.); (S.O.); (A.I.); (N.I.); (H.S.); (T.A.)
| | - Shinsaku Ochiai
- Hirakawa Zoological Park, Kagoshima 891-0133, Japan; (F.M.); (T.E.); (K.M.); (S.O.); (A.I.); (N.I.); (H.S.); (T.A.)
| | - Ayaka Ito
- Hirakawa Zoological Park, Kagoshima 891-0133, Japan; (F.M.); (T.E.); (K.M.); (S.O.); (A.I.); (N.I.); (H.S.); (T.A.)
| | - Nanao Ito
- Hirakawa Zoological Park, Kagoshima 891-0133, Japan; (F.M.); (T.E.); (K.M.); (S.O.); (A.I.); (N.I.); (H.S.); (T.A.)
| | - Hiroko Sakurai
- Hirakawa Zoological Park, Kagoshima 891-0133, Japan; (F.M.); (T.E.); (K.M.); (S.O.); (A.I.); (N.I.); (H.S.); (T.A.)
| | - Takayuki Asai
- Hirakawa Zoological Park, Kagoshima 891-0133, Japan; (F.M.); (T.E.); (K.M.); (S.O.); (A.I.); (N.I.); (H.S.); (T.A.)
| | - Kyoko Tsukiyama-Kohara
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan; (M.E.H.K.); (M.A.H.)
- Correspondence: ; Tel.: +81-99-285-3589
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11
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Kayesh MEH, Hashem MA, Tsukiyama-Kohara K. Koala retrovirus epidemiology, transmission mode, pathogenesis, and host immune response in koalas (Phascolarctos cinereus): a review. Arch Virol 2020; 165:2409-2417. [PMID: 32770481 PMCID: PMC7413838 DOI: 10.1007/s00705-020-04770-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 07/07/2020] [Indexed: 12/21/2022]
Abstract
Koala retrovirus (KoRV) is a major threat to koala health and conservation. It also represents a series of challenges across the fields of virology, immunology, and epidemiology that are of great potential interest to any researcher in the field of retroviral diseases. KoRV is a gammaretrovirus that is present in both endogenous and exogenous forms in koala populations, with a still-active endogenization process. KoRV may induce immunosuppression and neoplastic conditions such as lymphoma and leukemia and play a role in chlamydiosis and other diseases in koalas. KoRV transmission modes, pathogenesis, and host immune response still remain unclear, and a clear understanding of these areas is critical for devising effective preventative and therapeutic strategies. Research on KoRV is clearly critical for koala conservation. In this review, we provide an overview of the current understanding and future challenges related to KoRV epidemiology, transmission mode, pathogenesis, and host immune response and discuss prospects for therapeutic and preventive vaccines.
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Affiliation(s)
- Mohammad Enamul Hoque Kayesh
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan
- Department of Microbiology and Public Health, Faculty of Animal Science and Veterinary Medicine, Patuakhali Science and Technology University, Barishal, 8210, Bangladesh
| | - Md Abul Hashem
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan
- Department of Health, Chattogram City Corporation, Chattogram, 4000, Bangladesh
| | - Kyoko Tsukiyama-Kohara
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan.
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12
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Zheng H, Pan Y, Tang S, Pye GW, Stadler CK, Vogelnest L, Herrin KV, Rideout BA, Switzer WM. Koala retrovirus diversity, transmissibility, and disease associations. Retrovirology 2020; 17:34. [PMID: 33008414 PMCID: PMC7530975 DOI: 10.1186/s12977-020-00541-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 09/21/2020] [Indexed: 11/12/2022] Open
Abstract
Background Koalas are infected with the koala retrovirus (KoRV) that exists as exogenous or endogenous viruses. KoRV is genetically diverse with co-infection with up to ten envelope subtypes (A-J) possible; KoRV-A is the prototype endogenous form. KoRV-B, first found in a small number of koalas with an increased leukemia prevalence at one US zoo, has been associated with other cancers and increased chlamydial disease. To better understand the molecular epidemiology of KoRV variants and the effect of increased viral loads (VLs) on transmissibility and pathogenicity we developed subtype-specific quantitative PCR (qPCR) assays and tested blood and tissue samples from koalas at US zoos (n = 78), two Australian zoos (n = 27) and wild-caught (n = 21) in Australia. We analyzed PCR results with available clinical, demographic, and pedigree data. Results All koalas were KoRV-A-infected. A small number of koalas (10.3%) at one US zoo were also infected with non-A subtypes, while a higher non-A subtype prevalence (59.3%) was found in koalas at Australian zoos. Wild koalas from one location were only infected with KoRV-A. We observed a significant association of infection and plasma VLs of non-A subtypes in koalas that died of leukemia/lymphoma and other neoplasias and report cancer diagnoses in KoRV-A-positive animals. Infection and VLs of non-A subtypes was not associated with age or sex. Transmission of non-A subtypes occurred from dam-to-offspring and likely following adult-to-adult contact, but associations with contact type were not evaluated. Brief antiretroviral treatment of one leukemic koala infected with high plasma levels of KoRV-A, -B, and -F did not affect VL or disease progression. Conclusions Our results show a significant association of non-A KoRV infection and plasma VLs with leukemia and other cancers. Although we confirm dam-to-offspring transmission of these variants, we also show other routes are possible. Our validated qPCR assays will be useful to further understand KoRV epidemiology and its zoonotic transmission potential for humans exposed to koalas because KoRV can infect human cells.
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Affiliation(s)
- HaoQiang Zheng
- Laboratory Branch, Division of HIV/AIDS Prevention, Center for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, MS G4530329, USA
| | - Yi Pan
- Quantitative Sciences and Data Management Branch, Division of HIV/AIDS Prevention, Center for Disease Control and Prevention, Atlanta, GA, 30329, USA
| | - Shaohua Tang
- Laboratory Branch, Division of HIV/AIDS Prevention, Center for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, MS G4530329, USA
| | - Geoffrey W Pye
- San Diego Zoo Global, San Diego, CA, 92112, USA.,Disney's Animals, Science, and Environment, Bay Lake, FL, 32830, USA
| | | | - Larry Vogelnest
- Taronga Conservation Society Australia, Taronga Zoo, Mosman, NSW, 2088, Australia
| | | | | | - William M Switzer
- Laboratory Branch, Division of HIV/AIDS Prevention, Center for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, MS G4530329, USA.
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13
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Quigley BL, Timms P. Helping koalas battle disease - Recent advances in Chlamydia and koala retrovirus (KoRV) disease understanding and treatment in koalas. FEMS Microbiol Rev 2020; 44:583-605. [PMID: 32556174 PMCID: PMC8600735 DOI: 10.1093/femsre/fuaa024] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/14/2020] [Indexed: 12/31/2022] Open
Abstract
The iconic Australian marsupial, the koala (Phascolarctos cinereus), has suffered dramatic population declines as a result of habitat loss and fragmentation, disease, vehicle collision mortality, dog attacks, bushfires and climate change. In 2012, koalas were officially declared vulnerable by the Australian government and listed as a threatened species. In response, research into diseases affecting koalas has expanded rapidly. The two major pathogens affecting koalas are Chlamydia pecorum, leading to chlamydial disease and koala retrovirus (KoRV). In the last eight years, these pathogens and their diseases have received focused study regarding their sources, genetics, prevalence, disease presentation and transmission. This has led to vast improvements in pathogen detection and treatment, including the ongoing development of vaccines for each as a management and control strategy. This review will summarize and highlight the important advances made in understanding and combating C. pecorum and KoRV in koalas, since they were declared a threatened species. With complementary advances having also been made from the koala genome sequence and in our understanding of the koala immune system, we are primed to make a significant positive impact on koala health into the future.
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Affiliation(s)
- Bonnie L Quigley
- Genecology Research Centre, University of the Sunshine Coast,
90 Sippy Downs Drive, Sippy Downs, Queensland, 4556, Australia
| | - Peter Timms
- Genecology Research Centre, University of the Sunshine Coast,
90 Sippy Downs Drive, Sippy Downs, Queensland, 4556, Australia
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14
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Yap MW, Young GR, Varnaite R, Morand S, Stoye JP. Duplication and divergence of the retrovirus restriction gene Fv1 in Mus caroli allows protection from multiple retroviruses. PLoS Genet 2020; 16:e1008471. [PMID: 32525879 PMCID: PMC7313476 DOI: 10.1371/journal.pgen.1008471] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 06/23/2020] [Accepted: 05/13/2020] [Indexed: 12/29/2022] Open
Abstract
Viruses and their hosts are locked in an evolutionary race where resistance to infection is acquired by the hosts while viruses develop strategies to circumvent these host defenses. Forming one arm of the host defense armory are cell autonomous restriction factors like Fv1. Originally described as protecting laboratory mice from infection by murine leukemia virus (MLV), Fv1s from some wild mice have also been found to restrict non-MLV retroviruses, suggesting an important role in the protection against viruses in nature. We surveyed the Fv1 genes of wild mice trapped in Thailand and characterized their restriction activities against a panel of retroviruses. An extra copy of the Fv1 gene, named Fv7, was found on chromosome 6 of three closely related Asian species of mice: Mus caroli, M. cervicolor, and M. cookii. The presence of flanking repeats suggested it arose by LINE-mediated retroduplication within their most recent common ancestor. A high degree of natural variation was observed in both Fv1 and Fv7 and, on top of positive selection at certain residues, insertions and deletions were present that changed the length of the reading frames. These genes exhibited a range of restriction phenotypes, with activities directed against gamma-, spuma-, and lentiviruses. It seems likely, at least in the case of M. caroli, that the observed gene duplication may expand the breadth of restriction beyond the capacity of Fv1 alone and that one or more such viruses have recently driven or continue to drive the evolution of the Fv1 and Fv7 genes.
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Affiliation(s)
| | | | | | - Serge Morand
- Centre National de la Recherche Scientifique-Centre de coopération
Internationale en Recherche Agronomique pour le Développement Animal et Gestion
Intégrée des Risques, Faculty of Veterinary Technology, Kasetsart University,
Bangkok, Thailand
| | - Jonathan P. Stoye
- The Francis Crick Institute, London, United Kingdom
- Faculty of Medicine, Imperial College London, London, United
Kingdom
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15
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Abstract
Bats are reservoirs of emerging viruses that are highly pathogenic to other mammals, including humans. Despite the diversity and abundance of bat viruses, to date they have not been shown to harbor exogenous retroviruses. Here we report the discovery and characterization of a group of koala retrovirus-related (KoRV-related) gammaretroviruses in Australian and Asian bats. These include the Hervey pteropid gammaretrovirus (HPG), identified in the scat of the Australian black flying fox (Pteropus alecto), which is the first reproduction-competent retrovirus found in bats. HPG is a close relative of KoRV and the gibbon ape leukemia virus (GALV), with virion morphology and Mn2+-dependent virion-associated reverse transcriptase activity typical of a gammaretrovirus. In vitro, HPG is capable of infecting bat and human cells, but not mouse cells, and displays a similar pattern of cell tropism as KoRV-A and GALV. Population studies reveal the presence of HPG and KoRV-related sequences in several locations across northeast Australia, as well as serologic evidence for HPG in multiple pteropid bat species, while phylogenetic analysis places these bat viruses as the basal group within the KoRV-related retroviruses. Taken together, these results reveal bats to be important reservoirs of exogenous KoRV-related gammaretroviruses.
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16
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Sarker N, Fabijan J, Seddon J, Tarlinton R, Owen H, Simmons G, Thia J, Blanchard AM, Speight N, Kaler J, Emes RD, Woolford L, Trott D, Hemmatzadeh F, Meers J. Genetic diversity of Koala retrovirus env gene subtypes: insights into northern and southern koala populations. J Gen Virol 2019; 100:1328-1339. [PMID: 31329088 DOI: 10.1099/jgv.0.001304] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Koala retrovirus (KoRV) is a recently endogenized retrovirus associated with neoplasia and immunosuppression in koala populations. The virus is known to display sequence variability and to be present at varying prevalence in different populations, with animals in southern Australia displaying lower prevalence and viral loads than northern animals. This study used a PCR and next-generation sequencing strategy to examine the diversity of the KoRV env gene in both proviral DNA and viral RNA forms in two distinct populations representative of the 'northern' and 'southern' koala genotypes. The current study demonstrated that the full range of KoRV subtypes is present across both populations, and in both healthy and sick animals. KoRV-A was the predominant proviral subtype in both populations, but there was marked diversity of DNA and RNA subtypes within individuals. Many of the northern animals displayed a higher RNA viral diversity than evident in their proviral DNA, indicating relatively higher replication efficiency of non-KoRV-A subtypes. The southern animals displayed a lower absolute copy number of KoRV than the northern animals as reported previously and a higher preponderance of KoRV-A in individual animals. These discrepancies in viral replication and diversity remain unexplained but may indicate relative protection of the southern population from KoRV replication due to either viral or host factors and may represent an important protective effect for the host in KoRV's ongoing entry into the koala genome.
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Affiliation(s)
- Nishat Sarker
- Laboratory Sciences & Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh.,School of Veterinary Science, The University of Queensland, Queensland, Australia
| | - Jessica Fabijan
- School of Animal and Veterinary Sciences, The University of Adelaide, Adelaide, Australia
| | - Jennifer Seddon
- School of Veterinary Science, The University of Queensland, Queensland, Australia
| | - Rachael Tarlinton
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, UK
| | - Helen Owen
- School of Veterinary Science, The University of Queensland, Queensland, Australia
| | - Greg Simmons
- School of Veterinary Science, The University of Queensland, Queensland, Australia
| | - Joshua Thia
- School of Biological Sciences, The University of Queensland, Queensland, Australia
| | - Adam Mark Blanchard
- School of Animal, Rural and. Environmental Sciences, Nottingham Trent University, Nottingham NG1 4FQ, UK
| | - Natasha Speight
- School of Animal and Veterinary Sciences, The University of Adelaide, Adelaide, Australia
| | - Jasmeet Kaler
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, UK
| | - Richard David Emes
- Advanced Data Analysis Centre (ADAC), University of Nottingham, Nottingham, UK.,School of Veterinary Medicine and Science, University of Nottingham, Nottingham, UK
| | - Lucy Woolford
- School of Animal and Veterinary Sciences, The University of Adelaide, Adelaide, Australia
| | - Darren Trott
- School of Animal and Veterinary Sciences, The University of Adelaide, Adelaide, Australia
| | - Farhid Hemmatzadeh
- School of Animal and Veterinary Sciences, The University of Adelaide, Adelaide, Australia
| | - Joanne Meers
- School of Veterinary Science, The University of Queensland, Queensland, Australia
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17
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Fabijan J, Miller D, Olagoke O, Woolford L, Boardman W, Timms P, Polkinghorne A, Simmons G, Hemmatzadeh F, Trott DJ, Speight KN. Prevalence and clinical significance of koala retrovirus in two South Australian koala (Phascolarctos cinereus) populations. J Med Microbiol 2019; 68:1072-1080. [PMID: 31162024 DOI: 10.1099/jmm.0.001009] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PURPOSE Koala retrovirus (KoRV-A) is 100 % prevalent in northern Australian (Queensland and New South Wales) koala populations, where KoRV-B has been associated with Chlamydia pecorum disease and the development of lymphosarcoma. In southern populations (Victoria and South Australia), KoRV-A is less prevalent and KoRV-B has not been detected in Victoria, while the current prevalence in South Australian populations is unknown but is thought to be low. This study aimed to determine (i) the prevalence of KoRV in the two largest South Australian koala populations [Kangaroo Island (KI) and Mount Lofty Ranges (MLR)], (ii) KoRV subtype and (iii) if an association between KoRV and C. pecorum exists. METHODOLOGY Wild koalas were sampled in KI ( n =170) between 2014 and 2017 and in MLR ( n =75) in 2016. Clinical examinations were performed, with blood collected for KoRV detection and typing by PCR. RESULTS KoRV prevalence was 42.4 % [72/170, 95 % confidence interval (CI): 34.9-49.8 %] in KI and 65.3 % (49/75, 95 % CI: 54.6-76.1 %) in MLR. Only KoRV-A, and not KoRV-B, was detected in both populations. In MLR, there was no statistical association between KoRV and C. pecorum infection (P =0.740), or KoRV and C. pecorum disease status ( P=0.274), although KoRV-infected koalas were more likely to present with overt C. pecorum disease than subclinical infection (odds ratio: 3.15, 95 % CI: 0.91-5.39). CONCLUSION KoRV-A is a prevalent pathogen in wild South Australian koala populations. Future studies should continue to investigate KoRV and C. pecorum associations, as the relationship is likely to be complex and to differ between the northern and southern populations.
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Affiliation(s)
- Jessica Fabijan
- School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia
| | - Darren Miller
- School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia
| | - Olusola Olagoke
- University of the Sunshine Coast, Sippy Downs, Queensland, Australia
| | - Lucy Woolford
- School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia
| | - Wayne Boardman
- School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia
| | - Peter Timms
- University of the Sunshine Coast, Sippy Downs, Queensland, Australia
| | - Adam Polkinghorne
- University of the Sunshine Coast, Sippy Downs, Queensland, Australia
| | - Greg Simmons
- School of Veterinary Sciences, The University of Queensland, Gatton, Queensland, Australia
| | - Farhid Hemmatzadeh
- School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia
| | - Darren J Trott
- School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia
| | - K Natasha Speight
- School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia
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18
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McMichael L, Smith C, Gordon A, Agnihotri K, Meers J, Oakey J. A novel Australian flying-fox retrovirus shares an evolutionary ancestor with Koala, Gibbon and Melomys gamma-retroviruses. Virus Genes 2019; 55:421-424. [PMID: 30877415 DOI: 10.1007/s11262-019-01653-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 03/04/2019] [Indexed: 01/19/2023]
Abstract
A novel gamma-retroviral sequence (7912 bp), inclusive of both partial 5' and 3' long terminal repeat regions, was identified from the brain of a black flying-fox (Pteropus alecto), Queensland, Australia. The sequence was distinct from other retroviral sequences identified in bats and showed greater identity to Koala, Gibbon ape leukaemia, Melomys burtoni and Woolly monkey retroviruses, forming their own phylogenetic clade. This finding suggests that these retroviruses may have an unknown common ancestor and that further investigation into the diversity of gamma-retroviruses in Australian Pteropus species may elucidate their evolutionary origins.
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Affiliation(s)
- L McMichael
- School of Veterinary Science, University of Queensland, Gatton Campus, Gatton, QLD, 4343, Australia.
| | - C Smith
- Department of Agriculture and Fisheries, Health and Food Science Precinct, Biosecurity Sciences Laboratory, Biosecurity Queensland, 39 Kessels Road, Coopers Plains, QLD, 4108, Australia
| | - A Gordon
- Department of Agriculture and Fisheries, Health and Food Science Precinct, Biosecurity Sciences Laboratory, Biosecurity Queensland, 39 Kessels Road, Coopers Plains, QLD, 4108, Australia
| | - K Agnihotri
- Department of Agriculture and Fisheries, Health and Food Science Precinct, Biosecurity Sciences Laboratory, Biosecurity Queensland, 39 Kessels Road, Coopers Plains, QLD, 4108, Australia
| | - J Meers
- School of Veterinary Science, University of Queensland, Gatton Campus, Gatton, QLD, 4343, Australia
| | - J Oakey
- Department of Agriculture and Fisheries, Health and Food Science Precinct, Biosecurity Sciences Laboratory, Biosecurity Queensland, 39 Kessels Road, Coopers Plains, QLD, 4108, Australia
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19
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Johnson RN, O'Meally D, Chen Z, Etherington GJ, Ho SYW, Nash WJ, Grueber CE, Cheng Y, Whittington CM, Dennison S, Peel E, Haerty W, O'Neill RJ, Colgan D, Russell TL, Alquezar-Planas DE, Attenbrow V, Bragg JG, Brandies PA, Chong AYY, Deakin JE, Di Palma F, Duda Z, Eldridge MDB, Ewart KM, Hogg CJ, Frankham GJ, Georges A, Gillett AK, Govendir M, Greenwood AD, Hayakawa T, Helgen KM, Hobbs M, Holleley CE, Heider TN, Jones EA, King A, Madden D, Graves JAM, Morris KM, Neaves LE, Patel HR, Polkinghorne A, Renfree MB, Robin C, Salinas R, Tsangaras K, Waters PD, Waters SA, Wright B, Wilkins MR, Timms P, Belov K. Adaptation and conservation insights from the koala genome. Nat Genet 2018; 50:1102-1111. [PMID: 29967444 PMCID: PMC6197426 DOI: 10.1038/s41588-018-0153-5] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 04/30/2018] [Indexed: 11/16/2022]
Abstract
The koala, the only extant species of the marsupial family Phascolarctidae, is classified as 'vulnerable' due to habitat loss and widespread disease. We sequenced the koala genome, producing a complete and contiguous marsupial reference genome, including centromeres. We reveal that the koala's ability to detoxify eucalypt foliage may be due to expansions within a cytochrome P450 gene family, and its ability to smell, taste and moderate ingestion of plant secondary metabolites may be due to expansions in the vomeronasal and taste receptors. We characterized novel lactation proteins that protect young in the pouch and annotated immune genes important for response to chlamydial disease. Historical demography showed a substantial population crash coincident with the decline of Australian megafauna, while contemporary populations had biogeographic boundaries and increased inbreeding in populations affected by historic translocations. We identified genetically diverse populations that require habitat corridors and instituting of translocation programs to aid the koala's survival in the wild.
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Affiliation(s)
- Rebecca N Johnson
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia.
- School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia.
| | - Denis O'Meally
- School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia
- Animal Research Centre, Faculty of Science, Health, Education & Engineering, University of the Sunshine Coast, Maroochydore, Queensland, Australia
| | - Zhiliang Chen
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | | | - Simon Y W Ho
- School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia
| | - Will J Nash
- Earlham Institute, Norwich Research Park, Norwich, UK
| | - Catherine E Grueber
- School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia
- San Diego Zoo Global, San Diego, CA, USA
| | - Yuanyuan Cheng
- School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia
- UQ Genomics Initiative, University of Queensland, St Lucia, Queensland, Australia
| | - Camilla M Whittington
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia
| | - Siobhan Dennison
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
| | - Emma Peel
- School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia
| | | | - Rachel J O'Neill
- Department of Molecular and Cell Biology and Institute for Systems Genomics, University of Connecticut, Storrs, CT, USA
| | - Don Colgan
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
| | - Tonia L Russell
- Ramaciotti Centre for Genomics, University of New South Wales, Kensington, New South Wales, Australia
| | | | - Val Attenbrow
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
| | - Jason G Bragg
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
- National Herbarium of New South Wales, Royal Botanic Gardens & Domain Trust, Sydney, New South Wales, Australia
| | - Parice A Brandies
- School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia
| | - Amanda Yoon-Yee Chong
- Earlham Institute, Norwich Research Park, Norwich, UK
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Janine E Deakin
- Institute for Applied Ecology, University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Federica Di Palma
- Earlham Institute, Norwich Research Park, Norwich, UK
- Department of Biological Sciences, University of East Anglia, Norwich, UK
| | - Zachary Duda
- Department of Molecular and Cell Biology and Institute for Systems Genomics, University of Connecticut, Storrs, CT, USA
| | - Mark D B Eldridge
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
| | - Kyle M Ewart
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
| | - Carolyn J Hogg
- School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia
| | - Greta J Frankham
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
| | - Arthur Georges
- Institute for Applied Ecology, University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Amber K Gillett
- Australia Zoo Wildlife Hospital, Beerwah, Queensland, Australia
| | - Merran Govendir
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia
| | - Alex D Greenwood
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
- Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Takashi Hayakawa
- Department of Wildlife Science (Nagoya Railroad Co., Ltd.), Primate Research Institute, Kyoto University, Inuyama, Japan
- Japan Monkey Centre, Inuyama, Japan
| | - Kristofer M Helgen
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
- School of Biological Sciences, Environment Institute, Centre for Applied Conservation Science, and ARC Centre of Excellence for Australian Biodiversity and Heritage, University of Adelaide, Adelaide, South Australia, Australia
| | - Matthew Hobbs
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
| | - Clare E Holleley
- Australian National Wildlife Collection, National Research Collections Australia, CSIRO, Canberra, Australian Capital Territory, Australia
| | - Thomas N Heider
- Department of Molecular and Cell Biology and Institute for Systems Genomics, University of Connecticut, Storrs, CT, USA
| | - Elizabeth A Jones
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia
| | - Andrew King
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
| | - Danielle Madden
- Animal Research Centre, Faculty of Science, Health, Education & Engineering, University of the Sunshine Coast, Maroochydore, Queensland, Australia
| | - Jennifer A Marshall Graves
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
- Institute for Applied Ecology, University of Canberra, Bruce, Australian Capital Territory, Australia
- School of Life Sciences, La Trobe University, Bundoora, Victoria, Australia
| | - Katrina M Morris
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian, UK
| | - Linda E Neaves
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
- Royal Botanic Garden Edinburgh, Edinburgh, UK
| | - Hardip R Patel
- John Curtin School of Medical Research, Australian National University, Acton, Australian Capital Territory, Australia
| | - Adam Polkinghorne
- Animal Research Centre, Faculty of Science, Health, Education & Engineering, University of the Sunshine Coast, Maroochydore, Queensland, Australia
| | - Marilyn B Renfree
- School of BioSciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Charles Robin
- School of BioSciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Ryan Salinas
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Kyriakos Tsangaras
- Department of Translational Genetics, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Paul D Waters
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Shafagh A Waters
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Belinda Wright
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
- School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia
| | - Marc R Wilkins
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, New South Wales, Australia
- Ramaciotti Centre for Genomics, University of New South Wales, Kensington, New South Wales, Australia
| | - Peter Timms
- Faculty of Science, Health, Education & Engineering, University of the Sunshine Coast, Maroochydore, Queensland, Australia
| | - Katherine Belov
- School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, New South Wales, Australia
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20
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Simmons GS, Habarugira G. The Origins of Gibbon Ape Leukaemia Virus. Primates 2018. [DOI: 10.5772/intechopen.71694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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21
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Greenwood AD, Ishida Y, O'Brien SP, Roca AL, Eiden MV. Transmission, Evolution, and Endogenization: Lessons Learned from Recent Retroviral Invasions. Microbiol Mol Biol Rev 2018; 82:e00044-17. [PMID: 29237726 PMCID: PMC5813887 DOI: 10.1128/mmbr.00044-17] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Viruses of the subfamily Orthoretrovirinae are defined by the ability to reverse transcribe an RNA genome into DNA that integrates into the host cell genome during the intracellular virus life cycle. Exogenous retroviruses (XRVs) are horizontally transmitted between host individuals, with disease outcome depending on interactions between the retrovirus and the host organism. When retroviruses infect germ line cells of the host, they may become endogenous retroviruses (ERVs), which are permanent elements in the host germ line that are subject to vertical transmission. These ERVs sometimes remain infectious and can themselves give rise to XRVs. This review integrates recent developments in the phylogenetic classification of retroviruses and the identification of retroviral receptors to elucidate the origins and evolution of XRVs and ERVs. We consider whether ERVs may recurrently pressure XRVs to shift receptor usage to sidestep ERV interference. We discuss how related retroviruses undergo alternative fates in different host lineages after endogenization, with koala retrovirus (KoRV) receiving notable interest as a recent invader of its host germ line. KoRV is heritable but also infectious, which provides insights into the early stages of germ line invasions as well as XRV generation from ERVs. The relationship of KoRV to primate and other retroviruses is placed in the context of host biogeography and the potential role of bats and rodents as vectors for interspecies viral transmission. Combining studies of extant XRVs and "fossil" endogenous retroviruses in koalas and other Australasian species has broadened our understanding of the evolution of retroviruses and host-retrovirus interactions.
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Affiliation(s)
- Alex D Greenwood
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research (IZW) in the Forschungsverbund Berlin e.V., Berlin, Germany
| | - Yasuko Ishida
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Sean P O'Brien
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Alfred L Roca
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Maribeth V Eiden
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research (IZW) in the Forschungsverbund Berlin e.V., Berlin, Germany
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McKee J, Clark N, Shapter F, Simmons G. A new look at the origins of gibbon ape leukemia virus. Virus Genes 2017; 53:165-172. [DOI: 10.1007/s11262-017-1436-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 02/07/2017] [Indexed: 10/20/2022]
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Abstract
Although genetic transfer between viruses and vertebrate hosts occurs less frequently than gene flow between bacteriophages and prokaryotes, it is extensive and has affected the evolution of both parties. With retroviruses, the integration of proviral DNA into chromosomal DNA can result in the activation of adjacent host gene expression and in the transduction of host transcripts into retroviral genomes as oncogenes. Yet in contrast to lysogenic phage, there is little evidence that viral oncogenes persist in a chain of natural transmission or that retroviral transduction is a significant driver of the horizontal spread of host genes. Conversely, integration of proviruses into the host germ line has generated endogenous retroviral genomes (ERV) in all vertebrate genomes sequenced to date. Some of these genomes retain potential infectivity and upon reactivation may transmit to other host species. During mammalian evolution, sequences of retroviral origin have been repurposed to serve host functions, such as the viral envelope glycoproteins crucial to the development of the placenta. Beyond retroviruses, DNA viruses with complex genomes have acquired numerous genes of host origin which influence replication, pathogenesis and immune evasion, while host species have accumulated germline sequences of both DNA and RNA viruses. A codicil is added on lateral transmission of cancer cells between hosts and on migration of host mitochondria into cancer cells.
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Affiliation(s)
- Robin A Weiss
- Division of Infection and Immunity, University College London, Gower Street, London, WC1E 6BT, UK.
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Transspecies Transmission of Gammaretroviruses and the Origin of the Gibbon Ape Leukaemia Virus (GaLV) and the Koala Retrovirus (KoRV). Viruses 2016; 8:v8120336. [PMID: 27999419 PMCID: PMC5192397 DOI: 10.3390/v8120336] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 12/07/2016] [Accepted: 12/14/2016] [Indexed: 01/05/2023] Open
Abstract
Transspecies transmission of retroviruses is a frequent event, and the human immunodeficiency virus-1 (HIV-1) is a well-known example. The gibbon ape leukaemia virus (GaLV) and koala retrovirus (KoRV), two gammaretroviruses, are also the result of a transspecies transmission, however from a still unknown host. Related retroviruses have been found in Southeast Asian mice although the sequence similarity was limited. Viruses with a higher sequence homology were isolated from Melomys burtoni, the Australian and Indonesian grassland melomys. However, only the habitats of the koalas and the grassland melomys in Australia are overlapping, indicating that the melomys virus may not be the precursor of the GaLV. Viruses closely related to GaLV/KoRV were also detected in bats. Therefore, given the fact that the habitats of the gibbons in Thailand and the koalas in Australia are far away, and that bats are able to fly over long distances, the hypothesis that retroviruses of bats are the origin of GaLV and KoRV deserves consideration. Analysis of previous transspecies transmissions of retroviruses may help to evaluate the potential of transmission of related retroviruses in the future, e.g., that of porcine endogenous retroviruses (PERVs) during xenotransplantation using pig cells, tissues or organs.
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Affiliation(s)
- Katherine Brown
- Computational Genomics Analysis and Training MRC Centre for Computational Biology Weatherall Institute for Molecular Medicine University of Oxford OX3 9DS UK
| | - Rachael E. Tarlinton
- School of Veterinary Medicine and Science University of Nottingham Sutton Bonington Campus Loughborough LE12 5RD UK
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Abstract
A retroviral etiology for malignant neoplasias in koalas has long been suspected. Evidence for retroviral involvement was bolstered in 2000 by the isolation of a koala retrovirus (KoRV), now termed KoRV-A. KoRV-A is an endogenous retrovirus-a retrovirus that infects germ cells-a feature that makes it a permanent resident of the koala genome. KoRV-A lacks the genetic diversity of an exogenous retrovirus, a quality associated with the ability of a retrovirus to cause neoplasias. In 2013, a second KoRV isolate, KoRV-B, was obtained from koalas with lymphomas in the Los Angeles Zoo. Unlike KoRV-A, which is present in the genomes of all koalas in the United States, KoRV-B is restricted in its distribution and is associated with host pathology (neoplastic disease). Here, our current understanding of the evolution of endogenous and exogenous KoRVs, and the relationship between them, is reviewed to build a perspective on the future impact of these viruses on koala sustainability.
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Affiliation(s)
- Wenqin Xu
- Section on Directed Gene Transfer, Laboratory of Cellular and Molecular Regulation, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892;
| | - Maribeth V Eiden
- Section on Directed Gene Transfer, Laboratory of Cellular and Molecular Regulation, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892;
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Fiebig U, Keller M, Denner J. Detection of koala retrovirus subgroup B (KoRV-B) in animals housed at European zoos. Arch Virol 2016; 161:3549-3553. [PMID: 27638778 DOI: 10.1007/s00705-016-3064-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 09/12/2016] [Indexed: 12/14/2022]
Abstract
Many koalas carry an endogenous retrovirus, KoRV-A, in their genome. Recently, a second retrovirus, KoRV-B, was detected in koalas in Japanese and U.S. zoos. However, this virus is not endogenous, differs in the receptor binding site of the surface envelope protein, and uses a receptor different from that of KoRV-A. We describe here a KoRV-B found in koalas at zoos in Germany and Belgium that differs slightly from that found in the Los Angeles zoo.
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Affiliation(s)
- Uwe Fiebig
- Robert Koch Institute, Nordufer 20, D-13353, Berlin, Germany
| | - Martina Keller
- Robert Koch Institute, Nordufer 20, D-13353, Berlin, Germany
| | - Joachim Denner
- Robert Koch Institute, Nordufer 20, D-13353, Berlin, Germany.
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Endogenous Gibbon Ape Leukemia Virus Identified in a Rodent (Melomys burtoni subsp.) from Wallacea (Indonesia). J Virol 2016; 90:8169-80. [PMID: 27384662 DOI: 10.1128/jvi.00723-16] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 06/27/2016] [Indexed: 01/07/2023] Open
Abstract
UNLABELLED Gibbon ape leukemia virus (GALV) and koala retrovirus (KoRV) most likely originated from a cross-species transmission of an ancestral retrovirus into koalas and gibbons via one or more intermediate as-yet-unknown hosts. A virus highly similar to GALV has been identified in an Australian native rodent (Melomys burtoni) after extensive screening of Australian wildlife. GALV-like viruses have also been discovered in several Southeast Asian species, although screening has not been extensive and viruses discovered to date are only distantly related to GALV. We therefore screened 26 Southeast Asian rodent species for KoRV- and GALV-like sequences, using hybridization capture and high-throughput sequencing, in the attempt to identify potential GALV and KoRV hosts. Only the individuals belonging to a newly discovered subspecies of Melomys burtoni from Indonesia were positive, yielding an endogenous provirus very closely related to a strain of GALV. The sequence of the critical receptor domain for GALV infection in the Indonesian M. burtoni subsp. was consistent with the susceptibility of the species to GALV infection. The second record of a GALV in M. burtoni provides further evidence that M. burtoni, and potentially other lineages within the widespread subfamily Murinae, may play a role in the spread of GALV-like viruses. The discovery of a GALV in the most western part of the Australo-Papuan distribution of M. burtoni, specifically in a transitional zone between Asia and Australia (Wallacea), may be relevant to the cross-species transmission to gibbons in Southeast Asia and broadens the known distribution of GALVs in wild rodents. IMPORTANCE Gibbon ape leukemia virus (GALV) and the koala retrovirus (KoRV) are very closely related, yet their hosts neither are closely related nor overlap geographically. Direct cross-species infection between koalas and gibbons is unlikely. Therefore, GALV and KoRV may have arisen via a cross-species transfer from an intermediate host whose range overlaps those of both gibbons and koalas. Using hybridization capture and high-throughput sequencing, we have screened a wide range of rodent candidate hosts from Southeast Asia for KoRV- and GALV-like sequences. Only a Melomys burtoni subspecies from Wallacea (Indonesia) was positive for GALV. We report the genome sequence of this newly identified GALV, the critical domain for infection of its potential cellular receptor, and its phylogenetic relationships with the other previously characterized GALVs. We hypothesize that Melomys burtoni, and potentially related lineages with an Australo-Papuan distribution, may have played a key role in cross-species transmission to other taxa.
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Narayan EJ, Williams M. Understanding the dynamics of physiological impacts of environmental stressors on Australian marsupials, focus on the koala (Phascolarctos cinereus). BMC ZOOL 2016. [DOI: 10.1186/s40850-016-0004-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
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A non-invasive tool for assessing pathogen prevalence in koala (Phascolarctos cinereus) populations: detection of Chlamydia pecorum and koala retrovirus (KoRV) DNA in genetic material sourced from scats. CONSERV GENET RESOUR 2016. [DOI: 10.1007/s12686-016-0574-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Episodic Diversifying Selection Shaped the Genomes of Gibbon Ape Leukemia Virus and Related Gammaretroviruses. J Virol 2015; 90:1757-72. [PMID: 26637454 DOI: 10.1128/jvi.02745-15] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 11/24/2015] [Indexed: 01/06/2023] Open
Abstract
UNLABELLED Gibbon ape leukemia viruses (GALVs) are part of a larger group of pathogenic gammaretroviruses present across phylogenetically diverse host species of Australasian mammals. Despite the biomedical utility of GALVs as viral vectors and in cancer gene therapy, full genome sequences have not been determined for all of the five identified GALV strains, nor has a comprehensive evolutionary analysis been performed. We therefore generated complete genomic sequences for each GALV strain using hybridization capture and high-throughput sequencing. The four strains of GALV isolated from gibbons formed a monophyletic clade that was closely related to the woolly monkey virus (WMV), which is a GALV strain that likely originated in a gibbon host. The GALV-WMV clade in turn formed a sister group to the koala retroviruses (KoRVs). Genomic signatures of episodic diversifying selection were detected among the gammaretroviruses with concentration in the env gene across the GALV strains that were particularly oncogenic and KoRV strains that were potentially exogenous, likely reflecting their adaptation to the host immune system. In vitro studies involving vectors chimeric between GALV and KoRV-B established that variable regions A and B of the surface unit of the envelope determine which receptor is used by a viral strain to enter host cells. IMPORTANCE The gibbon ape leukemia viruses (GALVs) are among the most medically relevant retroviruses due to their use as viral vectors for gene transfer and in cancer gene therapy. Despite their importance, full genome sequences have not been determined for the majority of primate isolates, nor has comprehensive evolutionary analysis been performed, despite evidence that the viruses are facing complex selective pressures associated with cross-species transmission. Using hybridization capture and high-throughput sequencing, we report here the full genome sequences of all the GALV strains and demonstrate that diversifying selection is acting on them, particularly in the envelope gene in functionally important domains, suggesting that host immune pressure is shaping GALV evolution.
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Weiss RA. What's the host and what's the microbe? The Marjory Stephenson Prize Lecture 2015. J Gen Virol 2015; 96:2501-2510. [PMID: 26296666 DOI: 10.1099/jgv.0.000220] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The interchange between retroviruses and their hosts is an intimate one because retroviruses integrate proviral DNA into host chromosomal DNA as an obligate step in the replication cycle. This has resulted in the occasional transduction of host genes into retroviral genomes as oncogenes, and also led to the integration of viral genomes into the host germ line that gives rise to endogenous retroviruses. I shall reflect on the evolutionary consequences of these events for virus and host. Then, I shall discuss the emergence of non-viral infections of host origin, namely, how malignant cells can give rise to eukaryotic single cell 'parasites' that colonize new hosts and how these in turn have been colonized by host mitochondria.
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Affiliation(s)
- Robin A Weiss
- Division of Infection & Immunity, University College London, Gower Street, London WC1E 6BT, UK
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