Wild koala populations in Australia are in steep decline throughout much of their northern geographic range. Koala retrovirus (KoRV) is strongly associated with immunodeficiency and related diseases, including chlamydia. Koala populations are also threatened by environmental factors and such factors are thought to intrinsically interlinked to KoRV load and disease. Environmental stress factors (heat waves, droughts and habitat degradation) likely impair the koala’s ability to control KoRV replication, which leads to further immune depletion in a negative feedback loop manifesting in disease.

Research conducted by A/Prof Chappell and Dr Blyton has made major contributions to the understanding of koala retrovirus including; (i) the first study to utilize deep sequencing to analyse KoRV diversity and increased the total number of available KoRV envelope sequences from 9 to 117; (ii) the first description of the piRNA response against KoRV; (iii) the first determination that exogenous KoRV is primarily maternally transmitted; (iv) the first demonstration of a statistically significant association between KoRV load and Chlamydia infections, multiple disease pathologies and overall poor body condition score; (v) A comprehensive analysis of KoRV biogeography throughout the entire geographic range of koala.

Publications

Diversity and transmission of koala retrovirus: a case study in three captive koala populations

Joyce, Briony A., Blyton, Michaela D. J., Johnston, Stephen D., Meikle, William D., Vinette Herrin, Kimberly, Madden, Claire, Young, Paul R. and Chappell, Keith J. (2022). Diversity and transmission of koala retrovirus: a case study in three captive koala populations. Scientific Reports, 12 (1) 15787, 1-8. doi: 10.1038/s41598-022-18939-6

Geographic patterns of koala retrovirus genetic diversity, endogenization, and subtype distributions

Blyton, Michaela D. J., Young, Paul R., Moore, Ben D. and Chappell, Keith J. (2022). Geographic patterns of koala retrovirus genetic diversity, endogenization, and subtype distributions. Proceedings of the National Academy of Sciences, 119 (33) e2122680119, 1-11. doi: 10.1073/pnas.2122680119

Koala retrovirus load and non-A subtypes are associated with secondary disease among wild northern koalas

Blyton, Michaela D. J., Pyne, Michael, Young, Paul and Chappell, Keith (2022). Koala retrovirus load and non-A subtypes are associated with secondary disease among wild northern koalas. PLoS Pathogens, 18 (5) e1010513, 1-20. doi: 10.1371/journal.ppat.1010513

Koala retrovirus genetic diversity and transmission dynamics within captive koala populations

Joyce, Briony A., Blyton, Michaela D. J., Johnston, Stephen D., Young, Paul R. and Chappell, Keith J. (2021). Koala retrovirus genetic diversity and transmission dynamics within captive koala populations. National Academy of Sciences. Proceedings, 118 (38) e2024021118, e2024021118. doi: 10.1073/pnas.2024021118

Project members

Professor Keith Chappell

Group Leader
Chappell Group

Dr Jake O’Donnell

Postdoctoral research Fellow
Chappell Group