Project Leaders: Dr Ken McColl and Dr Mark Crane, CSIRO Australian Animal Health Laboratory
Aim: To determine the potential of Cyprinid herpesvirus 3 (CyHV-3) as a biocontrol agent for carp in Australia.
Koi herpesvirus (KHV) or Cyprinid herpesvirus 3 (CyHV-3) has devastated carp populations in the US, Israel, Europe and China. Having not yet presented in Australia, KHV may be a highly effective biocontrol if managed and implemented correctly as opposed to unregulated escape. Overseas evidence is very promising, suggesting KHV is species specific (carp only) and highly effective against carp. The Fish Diseases Laboratory at the high-security CSIRO Australian Animal Health Laboratory will examine the potential of KHV as a biological control agent for carp in Australia, undertaking a rigorous assessment of KHV in the laboratory against Australian native species and carp strains.
The project will also include:
- screening of wild Australian carp for cyprinid herpesviruses. At least two other cyprinid herpesviruses are known: CyHV-1 (carp pox) and CyHV-2 (goldfish haematopoietic virus). It is essential that samples of carp are screened from different areas of Australia in order to test for the presence of such potentially cross-reactive viruses that could conceivably confer a degree of resistance on Australian carp. Screening of carp would involve collaboration with epidemiologists to establish the sample sizes, and distribution of samples that would be required to be considered statistically significant.
- cross-protection studies between CyHV-1 and -3 (KHV). The outcome of screening wild Australian carp for cyprinid herpesviruses may generate the need to conduct some cross-protection studies between CyHV-1 and KHV.
- susceptibility of carp of different ages/sizes. It may be that KHV susceptibility is related to age, rather than size, of larvae.
- epidemiological considerations. Modelling that simulates the release of KHV in a naive population of carp is required to predict how effective KHV would be in the carp population, how it would spread, how it would persist, the influence of the hydrodynamics of different river systems on these parameters.
These preliminary studies will be strictly confined to the laboratory, and, even if the results are encouraging, it is likely to be many years, and after much public consultation, before the virus would be considered for use in a multi-pronged attempt to control carp in Australia.
- Methods for isolation and growth of KHV in cell culture established to international standards.
- Methods for detection and identification of KHV by PCR established to international standards.
- Demonstration that the KHV Indonesian strain is most effective strain.
- During collection of juvenile carp in May and June 2009, a number of larger carp were also collected. These were used for a PhD project (funded outside the IA CRC), and, in the process, some of these fish also provided further data on the susceptibility of Australian carp to KHV. These results complement earlier data (from January/February 2008) on the susceptibility of smaller Australian carp (approximately 1.8 – 4.4 cm) to KHV.
- From December 2008 to June 2009 immunocytochemical studies on KHV in tissue culture were conducted. Preliminary studies have indicated that viral antigens in tissue culture can be localised using the same commercial antibody that is also used for immunohistochemistry. At present, the procedure is in the final stages of being optimised.
- A large number of fish studies are being conducted in 2009-10. Animal Ethics Committee approval has been obtained for experiments on: (1) the susceptibility of carp at different ages/sizes; (2) the sensitivity of carp to infection, and excretion of virus; and, (3) the susceptibility of non-target fish species. These experiments are all contingent on the availability of juvenile carp.
Agus Sunarto and Lynette Williams.
IA CRC, Murray-Darling Basin Authority, CSIRO Australian Animal Health Laboratories.
McColl KA, Sunarto A, Williams LM and Crane M (2007) Koi herpesvirus: Dreaded pathogen or white knight? Aquaculture Health International 9: 4-6.
Saunders G, Cooke B, McColl K, Shine R and Peacock T (accepted 22 June 2009, in press) Modern approaches for the biological control of vertebrate pests: An Australian perspective. Biological Control
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