RHD Boost Plus

This project was designed to extend and significantly enhance the outcomes and outputs of the original RHD Boost project, and allow the broad-scale release of RHDV1 K5 into the Australian rabbit population to be more effectively monitored. Enhanced and broad-scale virus release and monitoring is necessary to:

• Maximise the impact of the virus on Australian rabbit populations
• More thoroughly assess efficacy and understand the impact of the release of K5 on rabbit populations in the field and under a range of environmental conditions and climatic regions, including where new strains and benign virus are present
• Estimate the benefits and costs of current and future investment in RHDV as a continuing source of biological control
• Enhance community ownership and involvement in the program.

The incursion of two new strains of calicivirus were reported in 2014 and 2015. In 2014, a strain closely related to an RHDVa strain from China was identified while a year later the presence of the antigenic variant RHDV2 was confirmed in wild and domestic rabbits. With thes addition of these two new strains, there are four different virulent calicivirus strains in the Australian environment, in addition to nonpathogenic strains of calicivirus that are also known to circulate.

For the impact assessment of K5 it was therefore critically important that reliable discriminative diagnostic assays were developed. This included effective assays for the molecular characterisation of the viruses recovered from dead or recovering rabbits during or shortly after virus outbreaks, as well as serological assays to discriminate between antibodies raised to the respective strains.