August 7, 2018

 

PRRS-resistant pigs produced through gene editing

 

 

Scientists from Roslin Institute in Scotland have produced pigs that are resistant to one of the world's costliest animal diseases, porcine reproductive and respiratory syndrome, or PRRS, through gene editing.

 

According to a news post on the institute's website, the scientists discovered that by changing its genetic code, pigs do not get infected with the virus at all.

 

The animals also showed no signs that the change in their DNA had any other impact on their health.

 

What the researchers did was to remove a small section of the CD163 gene, through which the virus infects pigs. They focused on the section of the receptor that the virus attaches to, leaving the rest of the molecule intact.

 

The PRRS virus causes breathing problems and deaths in young animals, and infected pregnant sows can lose their litter. PRRS is endemic in most pig-producing countries worldwide. Vaccines have mostly failed to stop the spread of the virus, which continues to evolve rapidly, costing the pig industry around $2.5 billion each year in lost revenue in the US and Europe alone.

 

Pigs exposed to virus

 

The research team collaborated with Genus PLC, a leading global animal genetics company, to produce pigs with the specific DNA change. It noted that previous studies had shown that cells from these animals were resistant to the virus in lab tests, but that this was the first time these pigs were exposed to the virus to see if they become infected.

 

It was found that none of the animals became ill when exposed to the virus, as blood tests found no trace of the infection.

 

In removing a small section of the CD163 gene, the researchers used gene-editing techniques. As such, the issue of acceptability of gene-edited meat entering our food chain may arise.

 

Dr Christine Tait-Burkard of Roslin Institute said there is also a need to carry out longer-term studies to confirm that these genetic changes do not have any unforeseen adverse effects on the animals. "If these studies are successful and the public are accepting of this technology, we would then be looking to work with pig breeding companies to integrate these gene edits into commercial breeding stocks", she said.

 

Prof. Alan Archibald, also of Roslin Institute, opined that gene editing is a powerful tool to help reduce losses in the farming industry while improving the health and welfare of the animals themselves.

 

While genetically modified animals are banned from the food chain in Europe, it is not clear what regulations would apply to gene-edited animals, as the approach is different.