Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 119, Issue 33, Pages -Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.2122680119
Keywords
koala retrovirus; geography; genetic diversity; endogenization; evolution
Categories
Funding
- Australian Research Council [LP140100751, DP180103362]
- Evolva Biotech A/S
- NSW Office of Environment and Heritage
- Conservation Ecology Trust
- Australian Research Council [LP140100751] Funding Source: Australian Research Council
Ask authors/readers for more resources
The distribution and genetic characteristics of koala retrovirus differ between northern and southern populations. Southern koalas carry partial endogenous viral sequences, while northern koalas carry exogenous viral subtypes. This suggests that the evolution and transmission of the koala retrovirus are influenced by geographic factors.
Koala retrovirus (KoRV) subtype A (KoRV-A) is currently in transition from exogenous virus to endogenous viral element, providing an ideal system to elucidate retroviral-host coevolution. We characterized KoRV geography using fecal DNA from 192 samples across 20 populations throughout the koala's range. We reveal an abrupt change in KoRV genetics and incidence at the Victoria/New South Wales state border. In northern koalas, pol gene copies were ubiquitously present at above five per cell, consistent with endogenous KoRV. In southern koalas, poi copies were detected in only 25.8% of koalas and always at copy numbers below one, while the env gene was detected in all animals and in a majority at copy numbers above one per cell. These results suggest that southern koalas carry partial endogenous KoRV-like sequences. Deep sequencing of the env hypervariable region revealed three putatively endogenous KoRV-A sequences in northern koalas and a single, distinct sequence present in all southern koalas. Among northern populations, env sequence diversity decreased with distance from the equator, suggesting infectious KoRV-A invaded the koala genome in northern Australia and then spread south. The exogenous KoRV subtypes (B to K), two novel subtypes, and intermediate subtypes were detected in all northern koala populations but were strikingly absent from all southern animals tested. Apart from KoRV subtype D, these exogenous subtypes were generally locally prevalent but geographically restricted, producing KoRV genetic differentiation among northern populations. This suggests that sporadic evolution and local transmission of the exogenous subtypes have occurred within northern Australia, but this has not extended into animals within southern Australia.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available