RHD Boost

Project Leader: Dr Glen Saunders, Industry and Investment NSW

Aim: To identify new Rabbit Haemorrhagic Disease Virus (RHDV) strains with high lethality to rabbits immune to endemic Australian Rabbit Calicivirus (RCV-A1) and rabbits resistant to infection with Czech 351 derived RHDV strains.

Projects:  7.t.12e

Project summary

RHD Boost is a strategic response to the apparent rising genetic resistance of rabbits to the RHDV Czech 351 strain and its limited effectiveness in temperate regions due to the endemic RCV-A1, which protects many rabbits from the RHDV strain. In Europe, new RHDVa strains are outcompeting the original RHDV strains in the field and strongly suppressing wild rabbit populations in cooler, wetter regions. If successful, RHD Boost has a calculated Net Present Value of over $1.4 Billion over 15 years, and will substantially reduce the impacts of rabbits on Australian plant biodiversity over the 5.3 million square kilometres currently infested.

The project evaluates new candidate RHDV strains. This includes screening to determine which candidate RHDV strains overcome rabbits with immunity to Czech 351, and research to confirm the competitive advantage of the new candidate RHDV strains. A decision framework to optimise the impacts from releasing candidate RHDV strains will also be developed.

RHD Boost comprises eight key activities: 1. Selecting RHDV strains;
2. Testing to ensure freedom from other agents; 3. Producing virus stock and undertaking preliminary screening; 4. Screening of virus strains for ability to overcome immunity to RCV-A1 and genetic resistance in wild rabbits; 5. Screening of wild rabbits for ability to overcome immunity to RHDV; 6. Demonstrating competitive advantage of selected strains;
7. Optimising the efficiency of delivery; 8. Developing a pre- and post RHD Boost release monitoring and evaluation plan.

The three major outputs are:

  • Up to 2 RHDV strains scientifically demonstrated to have a high lethality to wild rabbits immune to endemic Australian Rabbit Calicivirus (RCV-A1) and wild rabbits resistant to infection with Czech 351 derived RHDV strains, that perform well in both temperate and semi-arid Australia.
  • A decision framework for optimising the release of candidate RHDV strain/s in terms of initial establishment and likely regional impact based on a model of the interaction between RHDV and RCV-A1.
  • A pre- and post- RHD Boost release monitoring and evaluation plan to enable impact and performance to be robustly measured.

Key achievements

  • Australian Government approval obtained for the import of selected RHDV strains into secure facilities for research purposes.

Key deliverables

  • Up to 10 candidate RHDV strains investigated and up to five selected RHDV strains imported into secure facilities for research purposes.
  • Freedom from adventitious agent tests for imported RHDV strains demonstrated.
  • Production of master virus stock and preliminary screening commenced.

Project team

The research team includes Dr Peter Kirkland (recent winner of NSW Scientist of the Year Award) and Dr Andrew Read who is a member of Dr Kirkland’s team who is currently leading work to develop a freeze-dried RHDV product, Dr Tanja Strive, who recently described the endemic calicivirus – RCV-A1 – that is impeding the impact of RHDV in temperate areas, Dr Peter Kerr who has worked extensively on the biological control of rabbits and myxoma virus, Dr Brian Cooke (past winner of a Eureka Science Prize) who was instrumental in the research program to evaluate and import the original CZ351 RHDV strain in the 1990s and has many international links in this area of work, and the very experienced field ecologists Dr Glen Saunders and John Tracey who conducted the initial evaluations of the RHD bait delivery method.

Project partners

IA CRC, Meat and Livestock Australia, Australian Wool Innovation, Rabbit Free Australia, NSW Industry and Investment and CSIRO.

Further information

Forrester, NL, Boag, B, Buckley A, Moreau, G and Gould EA (In press) Co-circulation of widely disparate strains of Rabbit haemorrhagic disease virus could explain localised epidemicity in the United Kingdom. Virology.

Henzell RP, Cooke BD and Mutze GJ (2008) The future biological control of pest populations of European rabbits, Oryctolagus cuniculus. Wildlife Research 35, 633.

McIntosh MT, et al (2007) A pandemic strain of calicivirus threatens rabbit industries in the Americas. Journal of Virology 4:96.

Strive T, Wright JD and Robinson AJ (2009) Identification and partial characterisation of a new lagovirus in Australian wild rabbits. Journal of Virology 384(1), 97-105.

For further information, contact us.