A recent analysis shows that wild rabbits in Australia developed resistance to myxomavirus in a stepped manner, with the second step likely triggered by the introduction of European rabbit fleas.
It poses the question of whether further changes in resistance occurred following the advent of RHDV and RHDV2, but no such studies have been undertaken for almost 30 years. The authors (Cooke, Taggart & Patel) call for on-going studies of rabbit resistance and virus virulence to enable proactive management of bio-controls in Australia. See their Epidemiology and Infection paper here.
Due to the co-evolution of resistance and virulence, myxomatosis still kills around 50% of infected adult rabbits, remaining part of the Australian bio-control armoury against wild rabbits.