Rabbit Haemorrhagic Disease Virus (RHDV) was released in 1995 and has kept rabbit numbers low in semi-arid parts of Australia for over a decade. However, since 2003, night-time transect counts throughout
Australia have shown that rabbit numbers are steadily increasing. There is increasing evidence that rabbits are developing genetic resistance to RHDV. It is clear that in those areas where a resurgence of rabbits has been identified, RHD is no longer keeping rabbits below the threshold at which they cause severe damage to soils and native vegetation.
Australia had only one introduced RHDV strain (Czech 351 derived strain), which is relatively stable and is enabling rabbits to develop genetic resistance. Additionally, Australia’s one RHDV strain has limited effectiveness in temperate regions; areas that have high agricultural productivity and many threatened plant habitats. This is now known to be due to the impeding effect of an endemic rabbit calicivirus (RCV-A1). This project’s aim was to increase the genetic variability of RHD viruses in Australia to increase their impact or flexibility to co-evolve rapidly enough to match apparent increases in the rabbit’s resistance to infection.