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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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Lane MR, Lowe A, Vukcevic J, Clark RG, Madani G, Higgins DP, Silver L, Belov K, Hogg CJ, Marsh KJ. Health Assessments of Koalas after Wildfire: A Temporal Comparison of Rehabilitated and Non-Rescued Resident Individuals. Animals (Basel) 2023; 13:2863. [PMID: 37760263 PMCID: PMC10525633 DOI: 10.3390/ani13182863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 08/25/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023] Open
Abstract
Many koalas (Phascolarctos cinereus) required rehabilitation after the 2019/20 Australian megafires. Little is known about how the post-release health of rehabilitated koalas compares to non-rescued resident koalas. We evaluated health parameters in rehabilitated koalas and resident koalas in burnt and unburnt habitat in southern New South Wales, Australia. Health checks were undertaken within six weeks of fire (rehabilitated group), 5-9 months post-fire and 12-16 months post-fire. Body condition improved significantly over time in rehabilitated koalas, with similar condition between all groups at 12-16 months. Rehabilitated koalas therefore gained body condition at similar rates to koalas who remained and survived in the wild. The prevalence of Chlamydia pecorum was also similar between groups and timepoints, suggesting wildfire and rehabilitation did not exacerbate disease in this population. While there was some variation in measured serum biochemistry and haematology parameters between groups and timepoints, most were within normal reference ranges. Our findings show that koalas were generally healthy at the time of release and when recaptured nine months later. Landscapes in the Monaro region exhibiting a mosaic of burn severity can support koalas, and rehabilitated koala health is not compromised by returning them to burnt habitats 4-6 months post-fire.
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Affiliation(s)
- Murraya R. Lane
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia;
| | - Arianne Lowe
- Stromlo Veterinary Services, P.O. Box 3963, Weston, ACT 2611, Australia;
| | | | - Robert G. Clark
- Research School of Finance, Actuarial Studies and Statistics, The Australian National University, Canberra, ACT 2601, Australia;
| | - George Madani
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia;
| | - Damien P. Higgins
- Sydney School of Veterinary Science, The University of Sydney, Sydney, NSW 2006, Australia;
| | - Luke Silver
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia; (L.S.); (K.B.); (C.J.H.)
| | - Katherine Belov
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia; (L.S.); (K.B.); (C.J.H.)
| | - Carolyn J. Hogg
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia; (L.S.); (K.B.); (C.J.H.)
| | - Karen J. Marsh
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia;
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Beaman JE, Mulligan C, Moore C, Mitchell D, Narayan E, Burke da Silva K. Resident wild koalas show resilience to large-scale translocation of bushfire-rescued koalas. CONSERVATION PHYSIOLOGY 2023; 11:coac088. [PMID: 36726864 PMCID: PMC9885738 DOI: 10.1093/conphys/coac088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/11/2022] [Accepted: 01/12/2023] [Indexed: 06/18/2023]
Abstract
Wildlife translocation is increasingly utilized as a conservation management action, to mitigate the immediate negative effects of habitat loss and fragmentation (e.g. from land clearing or bushfires). Previous research has shown that stress responses can help or hinder survival in translocated wildlife and determine the efficacy of translocation as a conservation action. Yet these translocated animals are only one side of the equation, with translocation also potentially impacting the animals in the recipient population. We measured physiological markers of stress (faecal cortisol metabolite concentrations and neutrophil-lymphocyte ratios) and assessed health condition in a wild koala population one year after a major translocation of bushfire-rescued koalas on Kangaroo Island. We expected to find a high population density at the site (>0.75 koalas per hectare) and that resident koalas would show signs of chronic stress and ill health as a result of territorial conflict over food trees and reproductive opportunities. In contrast, we found that only one-fifth of the population remaining at the site were translocated koalas. The overall population density was also much lower (0.21 koalas per hectare) than anticipated. With no evidence of mass mortality at the site, we suggest that the majority of translocated koalas dispersed away from the site. Our stress marker measurements did not differ between the wild koalas and a sample of captive (non-display) koalas at the nearby Kangaroo Island Wildlife Park and were generally low compared to other studies. Veterinary examinations found that most koalas were in good body condition with very few diagnostic indicators of systemic ill health. Overall, our results suggest that, if there is adequate landscape-scale habitat connectivity and opportunity for dispersal, translocated koalas are likely to disperse from the site of release, with limited impacts on recipient koala populations at translocation release sites.
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Affiliation(s)
- Julian E Beaman
- College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042
| | - Connor Mulligan
- College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042
| | - Claire Moore
- College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042
| | - Dana Mitchell
- Kangaroo Island Wildlife Park, 4068 Playford Hwy, Duncan, South Australia 5223
- Kangaroo Island Koala & Wildlife Rescue Centre, 4068 Playford Hwy, Duncan, South Australia 5223
| | - Edward Narayan
- School of Agriculture and Food Sciences, The University of Queensland, Lawes, Queensland 4343
| | - Karen Burke da Silva
- College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042
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Blanchard AM, Emes RD, Greenwood AD, Holmes N, Loose MW, McEwen GK, Meers J, Speight N, Tarlinton RE. Genome Reference Assembly for Bottlenecked Southern Australian Koalas. Genome Biol Evol 2022; 15:6948355. [PMID: 36542479 PMCID: PMC9887267 DOI: 10.1093/gbe/evac176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 12/09/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022] Open
Abstract
Koala populations show marked differences in inbreeding levels and in the presence or absence of the endogenous Koala retrovirus (KoRV). These genetic differences among populations may lead to severe disease impacts threatening koala population viability. In addition, the recent colonization of the koala genome by KoRV provides a unique opportunity to study the process of retroviral adaptation to vertebrate genomes and the impact this has on speciation, genome structure, and function. The genome build described here is from an animal from the bottlenecked Southern population free of endogenous and exogenous KoRV. It provides a more contiguous genome build than the previous koala reference derived from an animal from a more outbred Northern population and is the first koala genome from a KoRV polymerase-free animal.
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Affiliation(s)
| | - Richard David Emes
- School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | | | - Nadine Holmes
- School of Life Sciences, University of Nottingham, United Kingdom
| | | | | | - Joanne Meers
- School of Veterinary Science, University of Queensland, Australia
| | - Natasha Speight
- School of Animal and Veterinary Sciences, University of Adelaide, Australia
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Diversity and transmission of koala retrovirus: a case study in three captive koala populations. Sci Rep 2022; 12:15787. [PMID: 36138048 PMCID: PMC9499970 DOI: 10.1038/s41598-022-18939-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 08/22/2022] [Indexed: 11/21/2022] Open
Abstract
Koala retrovirus is a recently endogenized retrovirus associated with the onset of neoplasia and infectious disease in koalas. There are currently twelve described KoRV subtypes (KoRV-A to I, K–M), most of which were identified through recently implemented deep sequencing methods which reveal an animals’ overall KoRV profile. This approach has primarily been carried out on wild koala populations around Australia, with few investigations into the whole-population KoRV profile of captive koala colonies to date. This study conducted deep sequencing on 64 captive koalas of known pedigree, housed in three institutions from New South Wales and South-East Queensland, to provide a detailed analysis of KoRV genetic diversity and transmission. The final dataset included 93 unique KoRV sequences and the first detection of KoRV-E within Australian koala populations. Our analysis suggests that exogenous transmission of KoRV-A, B, D, I and K primarily occurs between dam and joey. Detection of KoRV-D in a neonate sample raises the possibility of this transmission occurring in utero. Overall, the prevalence and abundance of KoRV subtypes was found to vary considerably between captive populations, likely due to their different histories of animal acquisition. Together these findings highlight the importance of KoRV profiling for captive koalas, in particular females, who play a primary role in KoRV exogenous transmission.
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Tarlinton RE, Legione AR, Sarker N, Fabijan J, Meers J, McMichael L, Simmons G, Owen H, Seddon JM, Dick G, Ryder JS, Hemmatzedah F, Trott DJ, Speight N, Holmes N, Loose M, Emes RD. Differential and defective transcription of koala retrovirus indicates the complexity of host and virus evolution. J Gen Virol 2022; 103. [PMID: 35762858 DOI: 10.1099/jgv.0.001749] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Koala retrovirus (KoRV) is unique amongst endogenous (inherited) retroviruses in that its incorporation to the host genome is still active, providing an opportunity to study what drives this fundamental process in vertebrate genome evolution. Animals in the southern part of the natural range of koalas were previously thought to be either virus-free or to have only exogenous variants of KoRV with low rates of KoRV-induced disease. In contrast, animals in the northern part of their range universally have both endogenous and exogenous KoRV with very high rates of KoRV-induced disease such as lymphoma. In this study we use a combination of sequencing technologies, Illumina RNA sequencing of 'southern' (south Australian) and 'northern' (SE QLD) koalas and CRISPR enrichment and nanopore sequencing of DNA of 'southern' (South Australian and Victorian animals) to retrieve full-length loci and intregration sites of KoRV variants. We demonstrate that koalas that tested negative to the KoRV pol gene qPCR, used to detect replication-competent KoRV, are not in fact KoRV-free but harbour defective, presumably endogenous, 'RecKoRV' variants that are not fixed between animals. This indicates that these populations have historically been exposed to KoRV and raises questions as to whether these variants have arisen by chance or whether they provide a protective effect from the infectious forms of KoRV. This latter explanation would offer the intriguing prospect of being able to monitor and selectively breed for disease resistance to protect the wild koala population from KoRV-induced disease.
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Affiliation(s)
- R E Tarlinton
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, UK
| | - A R Legione
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Australia
| | - N Sarker
- School of Veterinary Science, The University of Queensland, Brisbane, Australia
| | - J Fabijan
- Longleat Safari Park, Durrel Wildlife Conservation Trust, UK
| | - J Meers
- School of Veterinary Science, The University of Queensland, Brisbane, Australia
| | - L McMichael
- School of Veterinary Science, The University of Queensland, Brisbane, Australia
| | - G Simmons
- School of Veterinary Science, The University of Queensland, Brisbane, Australia
| | - H Owen
- School of Veterinary Science, The University of Queensland, Brisbane, Australia
| | - J M Seddon
- School of Veterinary Science, The University of Queensland, Brisbane, Australia
| | - G Dick
- Longleat Safari Park, Durrel Wildlife Conservation Trust, UK
| | - J S Ryder
- Garston Veterinary Group, Somerset, UK
| | - F Hemmatzedah
- School of Animal and Veterinary Sciences, University of Adelaide, Adelaide, Australia
| | - D J Trott
- School of Animal and Veterinary Sciences, University of Adelaide, Adelaide, Australia
| | - N Speight
- School of Animal and Veterinary Sciences, University of Adelaide, Adelaide, Australia
| | - N Holmes
- School of Life Sciences, University of Nottingham, Nottingham, UK
| | - M Loose
- School of Life Sciences, University of Nottingham, Nottingham, UK
| | - R D Emes
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, UK
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Blyton MDJ, Pyne M, Young P, Chappell K. Koala retrovirus load and non-A subtypes are associated with secondary disease among wild northern koalas. PLoS Pathog 2022; 18:e1010513. [PMID: 35588407 PMCID: PMC9119473 DOI: 10.1371/journal.ppat.1010513] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 04/08/2022] [Indexed: 01/17/2023] Open
Abstract
Koala Retrovirus (KoRV) has been associated with neoplasia in the vulnerable koala (Phascolarctos cinereus). However, there are conflicting findings regarding its association with secondary disease. We undertook a large-scale assessment of how the different KoRV subtypes and viral load are associated with Chlamydia pecorum infection and a range of disease pathologies in 151 wild koalas admitted for care to Currumbin Wildlife Hospital, Australia. Viral load (KoRV pol copies per ml of plasma) was the best predictor of more disease pathologies than any other KoRV variable. The predicted probability of a koala having disease symptoms increased from 25% to over 85% across the observed range of KoRV load, while the predicted probability of C. pecorum infection increased from 40% to over 80%. We found a negative correlation between the proportion of env deep sequencing reads that were endogenous KoRV-A and total KoRV load. This is consistent with suppression of endogenous KoRV-A, while the exogenous KoRV subtypes obtain high infection levels. Additionally, we reveal evidence that the exogenous subtypes are directly associated with secondary disease, with the proportion of reads that were the endogenous KoRV-A sequence a negative predictor of overall disease probability after the effect of KoRV load was accounted for. Further, koalas that were positive for KoRV-D or KoRV-D/F were more likely to have urogenital C. pecorum infection or low body condition score, respectively, irrespective of KoRV load. By contrast, our findings do not support previous findings that KoRV-B in particular is associated with Chlamydial disease. Based on these findings we suggest that koala research and conservation programs should target understanding what drives individual differences in KoRV load and limiting exogenous subtype diversity within populations, rather than seeking to eliminate any particular subtype.
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Affiliation(s)
- Michaela D. J. Blyton
- The University of Queensland, School of Chemistry and Molecular Biosciences, St Lucia, Queensland, Australia
| | - Michael Pyne
- Currumbin Wildlife Hospital and Foundation, Currumbin, Queensland, Australia
| | - Paul Young
- The University of Queensland, School of Chemistry and Molecular Biosciences, St Lucia, Queensland, Australia
| | - Keith Chappell
- The University of Queensland, School of Chemistry and Molecular Biosciences, St Lucia, Queensland, Australia
- The University of Queensland, Australian Institute of Bioengineering and Nanotechnology, St Lucia, Queensland, Australia
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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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TESTIS ABNORMALITIES IN A POPULATION OF SOUTH AUSTRALIAN KOALAS (PHASCOLARCTOS CINEREUS). J Wildl Dis 2021; 58:158-167. [PMID: 34797903 DOI: 10.7589/jwd-d-21-00055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 08/20/2021] [Indexed: 11/20/2022]
Abstract
Testis asymmetry, in which the testes in an individual differ in size, has recently been reported in koalas (Phascolarctos cinereus) in the Mount Lofty Ranges population of South Australia. We describe the morphology and histology of both testes from affected individuals in this population (n=56) and the parameters of koalas with normal-sized testes based on age and breeding season (n=56). Morphologic measurements included testis weight, length, width, and volume; histologic parameters included seminiferous tubule diameter, seminiferous epithelial height, and seminiferous tubule (interstitial tissue ratio and presence or absence of spermatozoa). Of the 56 koalas with intraindividual variation in testes size, 47 were classified as asymmetric and nine as microtestes. For koalas with asymmetric testes, all morphologic parameters were significantly decreased in the smaller testes compared with normal-sized testes, but for the histologic parameters, only seminiferous tubule diameter was significantly less. Histopathologic examination of the asymmetric testes showed 38 with normal parenchyma histologically indistinguishable between intraindividual testes, four with degeneration and atrophy, and three with hypoplasia, whereas examination of microtestes showed degeneration and atrophy in seven, hypoplasia in one, and aplasia in one. No association of testis size difference with Chlamydia pecorum infection was found in a subset of animals. For the 56 koalas with normal-sized testes, morphologic parameters were found to increase with age, and juvenile and young adults were found to have smaller seminiferous tubule diameters than adults. No differences were found between testes of koalas in the breeding and nonbreeding season. Overall, these findings indicate that testis asymmetry in koalas from the Mount Lofty Ranges population is common but not associated with decreased function, except where testis malformations such as hypoplasia or aplasia occur or when parenchyma has been disrupted by acquired disease.
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Koala retrovirus genetic diversity and transmission dynamics within captive koala populations. Proc Natl Acad Sci U S A 2021; 118:2024021118. [PMID: 34493581 DOI: 10.1073/pnas.2024021118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 05/18/2021] [Indexed: 12/27/2022] Open
Abstract
Koala populations are currently in rapid decline across Australia, with infectious diseases being a contributing cause. The koala retrovirus (KoRV) is a gammaretrovirus present in both captive and wild koala colonies that presents an additional challenge for koala conservation in addition to habitat loss, climate change, and other factors. Currently, nine different subtypes (A to I) have been identified; however, KoRV genetic diversity analyses have been limited. KoRV is thought to be exogenously transmitted between individuals, with KoRV-A also being endogenous and transmitted through the germline. The mechanisms of exogenous KoRV transmission are yet to be extensively investigated. Here, deep sequencing was employed on 109 captive koalas of known pedigree, housed in two institutions from Southeast Queensland, to provide a detailed analysis of KoRV transmission dynamics and genetic diversity. The final dataset included 421 unique KoRV sequences, along with the finding of an additional subtype (KoRV-K). Our analysis suggests that exogenous transmission of KoRV occurs primarily between dam and joey, with evidence provided for multiple subtypes, including nonendogenized KoRV-A. No evidence of sexual transmission was observed, with mating partners found to share a similar number of sequences as unrelated koala pairs. Importantly, both distinct captive colonies showed similar trends. These findings indicate that breeding strategies or antiretroviral treatment of females could be employed as effective management approaches in combating KoRV transmission.
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Stephenson T, Speight N, Low WY, Woolford L, Tearle R, Hemmatzadeh F. Molecular Diagnosis of Koala Retrovirus (KoRV) in South Australian Koalas ( Phascolarctos cinereus). Animals (Basel) 2021; 11:ani11051477. [PMID: 34065572 PMCID: PMC8161083 DOI: 10.3390/ani11051477] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/06/2021] [Accepted: 05/16/2021] [Indexed: 12/20/2022] Open
Abstract
Simple Summary Koala retrovirus (KoRV) is a significant threat to koalas across Australia. Koalas in northern koala populations (from New South Wales and Queensland) have KoRV inserted into their DNA and inherited to their offspring. Southern koala populations (from Victoria and South Australia) have KoRV infection spread through close contact of koalas. As such, there are koalas within South Australia that are not infected with KoRV. Accurate diagnosis of the infection of each koala is therefore fundamental for disease studies. Previous studies have shown differences in prevalence of different KoRV genes in the Mount Lofty Ranges Koala population; therefore, clarification is necessary. This study uses a large cohort (n = 216) and defines the diagnostic regions of the KoRV genome within the South Australian population. Using multiple molecular techniques, it demonstrates strong evidence for two clear groupings of koalas: KoRV positive and KoRV negative. Within this study, a population of 41% were shown to be KoRV positive and 57% were KoRV negative, with 2% inconclusive. This differentiation is of great importance when examining the clinical importance of KoRV infection within southern koalas. Abstract Koala retrovirus, a recent discovery in Australian koalas, is endogenised in 100% of northern koalas but has lower prevalence in southern populations, with lower proviral and viral loads, and an undetermined level of endogenisation. KoRV has been associated with lymphoid neoplasia, e.g., lymphoma. Recent studies have revealed high complexity in southern koala retroviral infections, with a need to clarify what constitutes positive and negative cases. This study aimed to define KoRV infection status in Mount Lofty Ranges koalas in South Australia using RNA-seq and proviral analysis (n = 216). The basis for positivity of KoRV was deemed the presence of central regions of the KoRV genome (gag 2, pol, env 1, and env 2) and based on this, 41% (89/216) koalas were positive, 57% (124/216) negative, and 2% inconclusive. These genes showed higher expression in lymph node tissue from KoRV positive koalas with lymphoma compared with other KoRV positive koalas, which showed lower, fragmented expression. Terminal regions (LTRs, partial gag, and partial env) were present in SA koalas regardless of KoRV status, with almost all (99.5%, 215/216) koalas positive for gag 1 by proviral PCR. Further investigation is needed to understand the differences in KoRV infection in southern koala populations.
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Affiliation(s)
- Tamsyn Stephenson
- School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy 5371, Australia; (N.S.); (L.W.); (F.H.)
- Correspondence:
| | - Natasha Speight
- School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy 5371, Australia; (N.S.); (L.W.); (F.H.)
| | - Wai Yee Low
- The Davies Livestock Research Centre, School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy 5371, Australia; (W.Y.L.); (R.T.)
| | - Lucy Woolford
- School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy 5371, Australia; (N.S.); (L.W.); (F.H.)
- Veterinary Diagnostics Laboratory, School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy 5371, Australia
| | - Rick Tearle
- The Davies Livestock Research Centre, School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy 5371, Australia; (W.Y.L.); (R.T.)
| | - Farhid Hemmatzadeh
- School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy 5371, Australia; (N.S.); (L.W.); (F.H.)
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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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McEwen GK, Alquezar-Planas DE, Dayaram A, Gillett A, Tarlinton R, Mongan N, Chappell KJ, Henning J, Tan M, Timms P, Young PR, Roca AL, Greenwood AD. Retroviral integrations contribute to elevated host cancer rates during germline invasion. Nat Commun 2021; 12:1316. [PMID: 33637755 PMCID: PMC7910482 DOI: 10.1038/s41467-021-21612-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 02/01/2021] [Indexed: 12/16/2022] Open
Abstract
Repeated retroviral infections of vertebrate germlines have made endogenous retroviruses ubiquitous features of mammalian genomes. However, millions of years of evolution obscure many of the immediate repercussions of retroviral endogenisation on host health. Here we examine retroviral endogenisation during its earliest stages in the koala (Phascolarctos cinereus), a species undergoing germline invasion by koala retrovirus (KoRV) and affected by high cancer prevalence. We characterise KoRV integration sites (IS) in tumour and healthy tissues from 10 koalas, detecting 1002 unique IS, with hotspots of integration occurring in the vicinity of known cancer genes. We find that tumours accumulate novel IS, with proximate genes over-represented for cancer associations. We detect dysregulation of genes containing IS and identify a highly-expressed transduced oncogene. Our data provide insights into the tremendous mutational load suffered by the host during active retroviral germline invasion, a process repeatedly experienced and overcome during the evolution of vertebrate lineages.
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Affiliation(s)
- Gayle K McEwen
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - David E Alquezar-Planas
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
- Australian Museum Research Institute, Australian Museum, Sydney, NSW, Australia
| | - Anisha Dayaram
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
- Institute for Neurophysiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Amber Gillett
- Australia Zoo Wildlife Hospital, Beerwah, QLD, Australia
| | - Rachael Tarlinton
- Faculty of Medicine and Health Sciences, University of Nottingham, Leicestershire, UK
| | - Nigel Mongan
- Faculty of Medicine and Health Sciences, University of Nottingham, Leicestershire, UK
| | - Keith J Chappell
- School of Chemistry & Molecular Biosciences, University of Queensland, Brisbane, QLD, Australia
| | - Joerg Henning
- School of Veterinary Science, University of Queensland, Brisbane, QLD, Australia
| | - Milton Tan
- Illinois Natural History Survey, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Peter Timms
- Genecology Research Center, University of the Sunshine Coast, Sippy Downs, QLD, Australia
| | - Paul R Young
- School of Chemistry & Molecular Biosciences, University of Queensland, Brisbane, QLD, Australia
| | - Alfred L Roca
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Alex D Greenwood
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany.
- Department of Veterinary Medicine, Freie Universität, Berlin, Germany.
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Tarlinton RE, Fabijan J, Hemmatzadeh F, Meers J, Owen H, Sarker N, Seddon JM, Simmons G, Speight N, Trott DJ, Woolford L, Emes RD. Transcriptomic and genomic variants between koala populations reveals underlying genetic components to disorders in a bottlenecked population. CONSERV GENET 2021. [DOI: 10.1007/s10592-021-01340-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
AbstractHistorical hunting pressures on koalas in the southern part of their range in Australia have led to a marked genetic bottleneck when compared with their northern counterparts. There are a range of suspected genetic disorders such as testicular abnormalities, oxalate nephrosis and microcephaly reported at higher prevalence in these genetically restricted southern animals. This paper reports analysis of differential expression of genes from RNAseq of lymph nodes, SNPs present in genes and the fixation index (population differentiation due to genetic structure) of these SNPs from two populations, one in south east Queensland, representative of the northern genotype and one in the Mount Lofty Ranges South Australia, representative of the southern genotype. SNPs that differ between these two populations were significantly enriched in genes associated with brain diseases. Genes which were differentially expressed between the two populations included many associated with brain development or disease, and in addition a number associated with testicular development, including the androgen receptor. Finally, one of the 8 genes both differentially expressed and with a statistical difference in SNP frequency between populations was SLC26A6 (solute carrier family 26 member 6), an anion transporter that was upregulated in SA koalas and is associated with oxalate transport and calcium oxalate uroliths in humans. Together the differences in SNPs and gene expression described in this paper suggest an underlying genetic basis for several disorders commonly seen in southern Australian koalas, supporting the need for further research into the genetic basis of these conditions, and highlighting that genetic selection in managed populations may need to be considered in the future.
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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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16
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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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Identification and Prevalence of Phascolarctid Gammaherpesvirus Types 1 and 2 in South Australian Koala Populations. Viruses 2020; 12:v12090948. [PMID: 32867109 PMCID: PMC7552032 DOI: 10.3390/v12090948] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/20/2020] [Accepted: 08/22/2020] [Indexed: 01/01/2023] Open
Abstract
To determine Phascolarctid gammaherpesviruses (PhaHV) infection in South Australian koala populations, 80 oropharyngeal swabs from wild-caught and 87 oropharyngeal spleen samples and swabs from euthanased koalas were tested using two specific PCR assays developed to detect PhaHV-1 and PhaHV-2. In wild-caught koalas, active shedding of PhaHV was determined by positive oropharyngeal samples in 72.5% (58/80) of animals, of which 44.8% (26/58) had PhaHV-1, 20.7% (12/58) PhaHV-2 and 34.5% (20/58) both viral subtypes. In the euthanased koalas, systemic infection was determined by positive PCR in spleen samples and found in 72.4% (63/87) of koalas. Active shedding was determined by positive oropharyngeal results and found in 54.0% (47/87) of koalas. Koalas infected and actively shedding PhaHV-1 alone, PhaHV-2 alone or shedding both viral subtypes were 48.9% (23/47), 14.9% (7/47) and 36.2% (17/47), respectively. Only 45.9% (40/87) were not actively shedding, of which 40.0% (16/40) of these had systemic infections. Both wild-caught and euthanased koalas actively shedding PhaHV-2 were significantly more likely to be actively shedding both viral subtypes. Active shedding of PhaHV-2 had a significant negative correlation with BCS in the euthanased cohort, and active shedding of PhaHV-1 had a significant positive relationship with age in both wild-caught and euthanased cohorts.
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