An Australian research team has achieved a world breakthrough for the humane control of animal pests by using a virus to render mice infertile, the Minister for Science, Mr Peter McGauran, announced today.
Scientists from the Vertebrate Biocontrol Cooperative Research Centre (CRC) and the John Curtin School of Medical Research at the Australian National University, in collaboration with CSIRO Division of Wildlife and Ecology, used a laboratory virus to deliver an agent to mice which makes them infertile potentially long enough to prevent mouse populations building up into plagues.
The success was achieved by a team which included Dr Ron Jackson, Dr Deborah Maguire, Dr Lyn Hinds and Professor Ian Ramshaw. The research was funded by the Vertebrate Biocontrol CRC, CSIRO and graingrowers through the Grains Research and Development Corporation.
This is the first clear proof that it is possible to use a virus as a "taxi" to carry immunocontraceptive genes which induce temporary infertility in mammals by immunising them against their own reproductive proteins.
It paves the way for the development of a totally new, humane way to control the reproduction of mice and other major pests of the Australian landscape and agriculture, particularly rabbits and foxes.
However, the team cautioned that their achievement represented only a technical proof of the concept in the laboratory, and it will be several years before research develops an effective technique for reducing fertility in wild populations in the field. Even then, a modified virus will have to pass intensive scrutiny by other scientists and the Australian government before it can be released.
"We have demonstrated, in the laboratory, that it is technically possible to use a virus to deliver an infertility agent, which will keep mice infertile long enough, we believe, to prevent plagues developing," Dr Hinds said.
"But it is likely to be 2005 at the earliest before anything is available for use in the field. The risks and the potential must be very carefully assessed and approval sought according to the proper regulatory processes."
The team equipped a laboratory virus, ectromelia or mousepox, with a gene coding for certain proteins that form the outer coat (or zona pellucida) of a mouse's egg. They then showed the modified virus would infect lab mice.
Stimulated by the virus, the mouse's immune system forms antibodies which create a barrier to stop mouse sperm from "docking" on the surface of the egg, and so prevent fertilisation from taking place.
The researchers have shown that the engineered virus is able to immunise laboratory mice against reproduction for periods up to 28 weeks.
Modelling of wild mouse populations indicates that this period of infertility, if it occurs at the right time, affects enough of the breeding females and lasts long enough, could prevent the build-up in mouse numbers which results in a plague.
"We were encouraged by our early results and believe they will lead to the ultimate development of a humane and effective way to curb the populations of vertebrate pests in Australia," said Dr Hinds.
"We are also aware that our work will stimulate national and international scientific debate about the issue of releasing modified viruses into the environment - even if they are specific to the pest animal and are otherwise quite harmless."
Research by the Vertebrate Biocontrol CRC and CSIRO is targeted at reducing the impact of introduced mammal pests on the Australian environment and agriculture. However, with up to one quarter of the world's grain supply vanishing down the throats of various pests - including rats and mice - every year, it could also in the long term become a technology vital to food security for a human population which is forecast to rise by 5.5 million to 10.5 billion by 2050.
The Vertebrate Biocontrol CRC, established and supported under the Australian Government's Cooperative Research Centres Program, is a collaboration involving Agriculture Western Australia, the Australian National University, CSIRO Division of Wildlife and Ecology, and the Western Australian Department of Conservation and Land Management.
Caption: Mouse plagues: CSIRO uses a virus to render mice infertile
Further information:
Dr Lyn Hinds, CSIRO/Vertebrate Biocontrol CRC 06 242 1729, 018 204 989
Hon. Peter McGauran, Minister for Science 06 277 7660
Prof Ian Ramshaw, John Curtin School of Medical Research 06 249 3623
Paula Fitzgerald, Vertebrate Biocontrol CRC 06 242 1724, 0418 626 860
World Wide Web: http://www.dwe.csiro.au/vbc/ecology.htm