GENET archive


ANIMALS: Nerve gas antidote made by GE goats

                                  PART 1

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SOURCE: British Broadcasting Corporation, UK



DATE:   24.07.2007

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Scientists have genetically modified goats to make a drug in their milk that protects against deadly nerve agents such as sarin and VX.

These poisons are known collectively as organophosphates - a group of chemicals that also includes some pesticides used in farming.

So far, the GM goats have made almost 15kg of a drug which binds to and neutralises organophosphate molecules.

Details appear in Proceedings of the National Academy of Sciences journal.

The drug, called recombinant butyrylcholinesterase, could be used as a protective ”prophylactic” drug and also to treat people after exposure to nerve gas.

The US Department of Defense is funding the development effort by biotech firm PharmAthene to the tune of $213m (£105m).

It regards the drug as a promising way to protect its troops against exposure to nerve agents on the battlefield.

Butyrylcholinesterase could also be stockpiled for use in the event of a terrorist attack on a city with chemical weapons.

It is an enzyme that is made in small quantities by the human body.

The compound can be purified from blood, but the yields are poor.

However, the team at PharmAthene has been able to produce butyrylcholinesterase in large, commercial quantities and, the company says, at a reasonable cost.


Tough task

”It is a very difficult molecule to produce. There is a long history of people trying to produce this in everything from insects to yeast to bacteria and mammalian cells,” said Dr Solomon Langermann of PharmAthene, a co-author on the PNAS paper.

”None of them has been able to produce anything beyond milligram amounts. In the goat, we can make two or three grams per litre.”

The researchers inserted DNA for making the human form of butyrylcholinesterase into a ”vector” molecule. This vector is then introduced into a goat embryo.

This allows the human gene to be incorporated into the goat’s DNA sequence. The resulting female animals, all healthy, produced large quantities of butyrylcholinesterase in their milk.

The high yields are partly down to ”control elements” - stretches of DNA added, along with the human gene, to the vector molecule.

These control elements regulate how much of the enzyme the goat produces and ensure that most of it is produced in the milk, rather than in other tissues.


Safety trial

Once the enzyme was purified from milk, the scientists injected it into guinea pigs, and saw that it remained active in the bloodstream.

The commercial name given to the butyrylcholinesterase enzyme is Protexia.

Dr Langermann said that Protexia was more effective than the combination of the drugs atropine and 2-PAM currently carried by soldiers for protection against nerve agents.

”Those (older) drugs get cleared from the blood very rapidly. Even if the soldier were to survive, they would have very severe neurological damage,” he told BBC News.

”With Protexia, you would survive and be able to go back on the battlefield.”

It is also effective against a variety of different organophosphate poisons.

The product is still several years from entering use; it needs to pass a safety trial and seek approvals from the US government.

                                  PART 2

------------------------------- GENET-news -------------------------------


SOURCE: People’s Daily Online, China

AUTHOR: China Daily, China


DATE:   24.07.2007

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The world’s first cloned rabbit produced from the somatic cells of a rabbit fetus passed a molecular biology test at the Chinese Academy of Agricultural Sciences last week.

Born on February 12, the female rabbit, which weighed 60 grams at birth, is now growing normally at an animal center in Shanghai.

The cloning experiment was conducted by Dr Li Shangang, a researcher at the National Center for Molecular Genetics and Animal Breeding of the Beijing Institute of Animal Sciences.

Since the first somatic cell-cloned sheep, Dolly, was born in 1996, scientists have cloned mice, cattle and pigs.

But it was only in 2002 that French scientists produced the world’s first cloned rabbit using ovum cumulus cells from an adult female rabbit.

But the one in China is quite different as it is the first cloned using fibroblast cells from a fetal rabbit.

”Fibroblast cells from fetal rabbits can be cultured for longer periods than those from adult rabbits; so they are better materials for gene modification and gene targeting research,” Li told China Daily.

Li and his colleagues selected the back skin cells of a 20-day old rabbit embryo and cultured them into fibroblast cell lines. They then used the fibroblast cells as the donor cell and fused it with an enucleated rabbit’s oocyte (immature egg cell of animal ovary) through electric pulse.

Finally, they transferred the cloned embryos into the rabbit’s oviduct. After a month-long normal pregnancy, the cloned rabbit was born.

Rabbits are an important research tool as they have a much shorter gestation period than larger mammals such as sheep or cows.

”The advantage is that rabbits reproduce so quickly. Combined with the cloning technique, this would allow researchers to create genetically modified rabbits for medical research very quickly,” Li said.

For example, scientists have conducted research on creating a rabbit model for cystic fibrosis caused by a gene defect to improve progress on understanding and treating the disease.

China began cloning research more than three decades ago and produced the first cloned animal, a goat, in 2000.

”Chinese cloning research has reached a global advanced level,” Wang Hongguang, director of the China Center for Biotechnology Development affiliated to the Ministry of Science and Technology, said.

”We can reproduce almost all the cloning results in top-class laboratories around the world. However, we are lacking in original creations such as the newly cloned rabbit,” Wang told China Daily.

China has announced at the United Nations that it opposes human cloning for reproduction but backs life extension such as therapeutic cloning of human organs and creating new tissues to replace defective ones.



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