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Genetic diversity of Koala retrovirus (KoRV) env gene subtypes: Insights into northern and southern koala populations

Sarker, Nishat; Fabijan, Jessica; Seddon, Jennifer; Tarlinton, Rachael; Owen, Helen; Simmons, Greg; Thia, Joshua; Mark Blanchard, Adam; Speight, Natasha; Kaler, Jasmeet; Emes, Richard David; Woolford, Lucy; Trott, Darren; Hemmatzadeh, Farhid; Meers, Joanne


Nishat Sarker

Jessica Fabijan

Jennifer Seddon

Helen Owen

Greg Simmons

Joshua Thia

Natasha Speight

Professor of Epidemiology & Precision Livestock Informatics

Richard David Emes

Lucy Woolford

Darren Trott

Farhid Hemmatzadeh

Joanne Meers


Koala retrovirus (KoRV) is a recently endogenised 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.


Sarker, N., Fabijan, J., Seddon, J., Tarlinton, R., Owen, H., Simmons, G., …Meers, J. (2019). Genetic diversity of Koala retrovirus (KoRV) env gene subtypes: Insights into northern and southern koala populations. Journal of General Virology, 100(9), 1328-1339.

Journal Article Type Article
Acceptance Date Jul 3, 2019
Online Publication Date Jul 22, 2019
Publication Date Sep 1, 2019
Deposit Date Jul 8, 2019
Publicly Available Date Jul 8, 2019
Journal The Journal of general virology
Print ISSN 0022-1317
Electronic ISSN 1465-2099
Publisher Microbiology Society
Peer Reviewed Peer Reviewed
Volume 100
Issue 9
Pages 1328-1339
Keywords KoRV, env subtype, Koala, KoRV-B, Genetic diversity
Public URL
Publisher URL
Additional Information © 2019 The Authors. The definitive peer reviewed, edited version of this article is published in Journal of General Virology doi: 10.1099/jgv.0.001304


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