Abstract

The koala retrovirus (KoRV) is associated with outbreaks of Chlamydia and leukemia in wild and zoo koalas (Phascolarctos cinereus). Although endogenous retrovirus-like elements (ERVs) are common in the genomes of all vertebrates (comprising ca 8% of the human genome), KoRV is the only retrovirus known to be currently in the process of transitioning from exogenous to endogenous form. Here, we examine how other host-pathogen interactions, including other host-ERV systems, can inform our understanding of KoRV in koalas. We note that as an exogenous retrovirus becomes endogenous, there would be a dramatic reduction in mutation rates, which may shift the process of accommodation from the pathogen to the host. The low genetic diversity present in koalas may be in part responsible for the failure of the species to develop genetic resistance to KoRV. Isolation between koala populations may have hindered the geographic spread of the virus, but may also hinder selective sweeps of beneficial host alleles or beneficial proviral mutations, thereby precluding rapid increases in host fitness. In humans, some ERVs are involved in normal host functions such as placentation, or in the pathogenesis of diseases such as Hodgkin’s lymphoma. However, ERVs present in humans and other species are ancient, precluding prospective studies of germ line invasions. By contrast, the ongoing invasion of the koala germ line by KoRV provides a singular opportunity to study retroviral endogenization as it is occurring. This research can benefit the health of both humans and koalas.

 
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Bibliographic Data

Short Form
Roca and Greenwood, 2014. Tech. Rep. Aust. Mus., Online 24: 5–10
Author
Alfred L. Roca; Alex D. Greenwood
Year
2014
Title
The evolution of koala retroviruses: insights from other endogenous retroviruses
Serial Title
Technical Reports of the Australian Museum, Online
Volume
24
Start Page
5
End Page
10
DOI
10.3853/j.1835-4211.24.2014.1606
Language
English
Date Published
30 May 2014
Cover Date
30 May 2014
ISSN
1835-4211 (online)
Publisher
The Australian Museum
Place Published
Sydney, Australia
Subjects
RETROVIRUS; ANIMAL DISEASE; VIROLOGY; MAMMALIA: MARSUPIALIA
Digitized
30 May 2014
Available Online
30 May 2014
Reference Number
1606
EndNote
/Uploads/Journals/30978/1606.enw
Title Page
/Uploads/Journals/30978/1606.pdf
File size: 160kB
Complete Work
/Uploads/Journals/30978/1606_complete.pdf
File size: 413kB