- The Washington Times - Tuesday, August 13, 2002

SYDNEY, Australia Researchers have developed a process to genetically engineer viruses to decimate targeted feral pests, such as mice and rabbits, by making them sterile.
The researchers, from the Pest Animal Control Cooperative Research Center in Canberra, said they have been working on the project for more than 10 years.
The process, called immuno-contraception, causes infected females to produce antibodies against their own eggs, damaging them and blocking fertilization.
Rabbits, a nonnative species with no natural predators, are threatening to overrun Australia. They invade farms to feast on carrots and other vegetables, and they gobble up plants that are needed to prevent erosion.
The immuno-contraception idea has been tested against a major pest: the European house mouse.
An engineered herpes virus, Murine cytomegalovirus, has produced 100 percent sterilization of female mice in laboratory trials.
It is an idea with massive global implications, researchers say.
"In Australia, mouse plagues cost the country $75 million in lost production," said project director Tony Peacock.
Elsewhere, the rodent problem is even bigger. "Rice field rats in Asia eat $9 billion worth of rice every year," Mr. Peacock said. "That's one-third of the Asian rice crop. If we can successfully develop the virus in mice, as we appear to be able to do, then we believe we can also do it in rats."
The research team also is working on engineering a virus for rabbits Australia's No. 1 pest by adding a gene to the myxoma virus that devastated rabbit populations when they appeared in Australia 51 years ago.
In the intervening years, the rabbits became resistant to myxoma and overran the country.
This led scientists to release in the 1990s a virus called the rabbit calicivirus disease, which drastically reduced rabbit populations. Today, however, about 300 million rabbits dwell in the southern half of the country.
Mr. Peacock said he hopes the transgenic myxoma virus will be even more effective than the original strain. In two trials this year, it sterilized eight out of 11 female domestic rabbits a success rate of more than 70 percent.
"We're not promoting the virus as a magic bullet," Mr. Peacock said. "There will always be a residual population. It will need to be used as part of an integrated approach."
He clearly is hoping the expression, "to breed like rabbits," will become a thing of the past.
Apart from its effectiveness, Mr. Peacock said, the virus is more humane than such methods as poisoning and shooting.
Biological controls are not new to Australia. In recent years, bacteria, parasitic wasps, sap-sucking bugs and parasitic worms have been released into the wild.
Although many have been successful, some species have become problems. The cane toad, introduced in Queensland in 1935 to control beetles that were ruining sugarcane crops, is an example of a biological agent that multiplied out of control.

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