'Gene-editing' expected to develop disease-resistant breeds
SCIENTISTS have developed a method of creating genetically modified animals that addresses one of the main objections of the anti-GM movement.
The "gene-editing" technique is at least 10 times more efficient than existing GM technology and crucially does not involve the use of antibiotic-resistance genes, which has been heavily criticised by opponents.
The development could accelerate the creation of new breeds of GM animals for food and make it easier for biotechnology companies to win regulatory approval for novel types of livestock.
However, they still face the formidable obstacle of public acceptance of GM animals, which are seen by many as unnecessary and cruel.
Researchers at the Roslin Institute in Edinburgh, where Dolly the cloned sheep was created in 1996, announced yesterday that they have created the first GM pig with the technique as part of an ambitious project to produce disease-resistant animals by genetic engineering.
The male piglet, dubbed "Pig 26" and born last August, has been genetically engineered with the smallest of DNA mutations - a single deletion of one out of the 3 billion chemical "letters" of its entire genome.
Scientists said that the power of the new gene-editing technique is that it is extremely precise and improves the efficiency of creating GM animals by ten-fold or more.
It can be performed on fertilised eggs rather than ordinary tissue cells and does not need the antibiotic-resistant "markers" and the elaborate cloning process that previous techniques relied on.
Professor Bruce Whitelaw of the Roslin said that the new technique produces GM animals with between 10 and 15 per cent efficiency, compared with an efficiency of less than 1 per cent for the standard method of genetic engineering.
"We can do it without any marker or trace. Unless you do an audit trail there is no way that you would know how that mutation happened. It could have happened naturally, or by a DNA editor," he said.
In effect, because the new gene-editing technique does not leave any mark in the animal's genome other than the desired mutation, it merely mimics the natural evolutionary process.
"With the new technology we can work directly within the zygote [fertilised egg] with an efficiency of 10 to 15 per cent. In a litter of pigs at least one of the animals will have the edited event," Professor Whitelaw said.
"We can get rid of antibiotic resistance and for some situations we can get rid of cloning or nuclear-transfer technology as well. I think cloning does have some baggage attached to it.
We as scientists are very excited about this because of very precise changes, and we see this as very powerful, but whether the public will see that as inherently different is another matter altogether," he added.
Pig 26 is part of a research programme to create GM pigs resistant to infections such as African swine fever virus.
Public opposition to GM food has halted the introduction of the technology in crops and farm animals.
However, a GM salmon could soon be the first GM animal to be declared safe to eat in the US.
The US Food and Drug Administration is near to a decision on whether to allow Aquabounty Technologies of Massachusetts to produce its GM Atlantic salmon.