Rabbits are Australian agricultures most costly vertebrate pest animal: the annual cost exceeds $215 million.
The RHD-Boost project has identified a new strain of RHDV from South Korea (referred to as K5) that is suitable for release into Australia’s rabbit population. K5 has been shown to better overcome the protective effects of the benign virus RCV-A1 amongst the strains tested.
This project will extend and significantly enhance the outcomes and outputs of the original RHD Boost project, which will 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;
Recently the incursion of two new strains of calicivirus has been reported. In 2014 a strain closely related to an RHDVa strain from China was identified and, in 2015, the presence of the antigenic variant RHDV2 was confirmed in wild and domestic rabbits. With these two new strains there will be 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 is therefore critically important that reliable discriminative diagnostic assays are developed. This includes 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.
To expand and significantly enhance the planned release of K5 to include >40 broad-scale sites
This project is funded through an external research grant separate to the Centre for Invasive Species Solutions current innovation portfolio
This project coordinated, managed and evaluated the release of RHDV1 K5 across more than 323 community sites and 9 intensively monitored sites.
Analysis showed that RHDV1-K5 appears to work as a biocide; it is effective at a local scale, but generally does not spread like a self-disseminating biocontrol agent does.
A complicating factor during the project was the incursion of a new rabbit virus, RHDV2 in mid-2015. RHDV2 reduced rabbit numbers by 60% at 8 of the 18 intensively-monitored sites, making it much harder to show additional reductions in rabbit numbers at these sites, post RHDV1-K5 release.
Data analysis from the RHDV1 K5 release has shown a national average reduction of 34% post release. The intensively-monitored sites showed no significant change in quarterly rabbit growth rate following the release.
A full write up about this national release can be found at – https://invasives.com.au/our-solutions/impact-through-collaboration/national-release-rhdv1-k5-rabbit-biocontrol-agent
Cox, T.E., Ramsey, D.S.L., Sawyers, E. et al (2019). The impact of RHDV-K5 on rabbit populations in Australia: an evaluation of citizen science surveys to monitor rabbit abundance. Sci Rep 9,15229 https://doi.org/10.1038/s41598-019-51847-w
Ramsey, D. S. L., Cox, T., Strive, T., Forsyth, D. M., I., S., Hall, R., . . . Campbell, S. (2020). Emerging RHDV2 suppresses the impact of endemic and novel strains of RHDV on wild rabbit populations. Journal of Applied Ecology. https://doi.org/10.1111/1365-2664.13548