英科学家用基因编辑造“抗病猪”

不少人都听说过用转基因改造生物。多年来，科学家一直在研究修改生物和植物的DNA¹，以从某种方式上改变它们的特征。生活中最常见的例子就是转基因食品。现在，科学家可对猪的基因进行改造，从而提起它们的存活率。他们使用的技术不是转基因，而是基因编辑。区别是什么呢？

 

By now, most of us will have heard of GMOs. In case you haven't, GMO stands for genetically-modified organism. This basically means that an organism has had a foreign genetic² sequence introduced into it. In theory, this gives the organism certain advantages – it may become hardier⁴ by developing a resistance to disease, or in the case of GM food, may be bigger and require fewer nutrients⁵ to develop.

 

GM organisms have been used for a while. Scientists in the UK are trialling a GM wheat which allegedly yields40% more crop in greenhouse conditions. GM hens, which are able to lay eggs from different poultry⁶ breeds, have been used by scientists in Edinburgh to conserve⁷ rare birds by storing their stem cells in a seed bank. And more recently, scientists in China used information from the genome of a plant to increase the production of a key malaria⁸ drug, helping⁹ to meet the large global demand.

 

But now scientists at the University of Edinburgh's Roslin Institute have created GE pigs which are allegedly immune to one of the world's costliest¹⁰ livestock¹¹ diseases. GE stands for gene³ editing. Unlike GM, gene editing merely alters the DNA of the creature. In this case, a small region of pig DNA was deleted, preventing contraction¹² of the PRRS virus, or Porcine Reproductive and Respiratory Syndrome¹³ virus.

 

The virus causes breathing problems and death, but even after the GE pigs were exposed to it, none have become ill. And the effect is permanent, so the resistance will be passed on through natural breeding. Tests so far showed that the animals are not weakened in any other way by the process, claims Research leader Dr Christine Tait-Burkard. "The main thing that this edit will do is benefit animal welfare because the animals will not get a devastating¹⁴ disease."

 

However, critics have argued that the creature's welfare will actually suffer because of this. Helen Browning of the Soil Association believes this only addresses the symptom of the problem and not the root cause. "It is not encouraging companies to change the way they keep their pigs so they don't become diseased in the first place", she says.

 

Regardless, this is an experiment and while the technique appears to work, it is several years away from regulation and implementation¹⁵. "On top of that, only if these studies are successful and the public are accepting, would we integrate these gene edits into commercial breeding stocks," Dr Tait-Burkard told the BBC.  So it seems we may have a while yet.

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