Evolutionary changes have been identified within myxoma strains in Australia. The research, supported by Foundation for Rabbit-Free Australia, could have practical outcomes for future biocontrols.
RHDV2 is the dominant rabbit biocontrol in Australia but myxomatosis still persists with sporadic outbreaks, often having significant effect. However, little is known about the evolution of the virus, especially since the release of RHDV-K5 and arrival of RHDV2.
Earlier research by the late Dr Peter Kerr and colleagues at CSIRO identified three lineages of myxomatosis, A, B and C – with C showing an elevated rate of evolutionary change.
Assisted by funding from Rabbit-Free Australia, and the provision of rabbit samples from other laboratories and fresh field specimens, Dr Kandarp Patel and partners (from Adelaide University) investigated the nature of currently circulating strains of myxomatosis.
The studies identified two branches (X and Y) likely belonging to lineage A, with branch Y having a greater rate of evolution than X. It is speculated that environmental changes, such as the new strains of RHDV and possibly drought conditions in some regions, changed selection pressures on the virus resulting in a changed trajectory and speed of evolution.
This work invites challenge trials to discover if changes have occurred in virus virulence and in rabbit resistance, and to determine if there could be practical applications for future biocontrols in Australia. For more information, see the Final Report here.