Together, we stopped the market release of the world’s first genetically engineered (genetically modified or GM) pig, called the “Enviropig” (2012). We also stopped production of the world’s first GM food animal, the GM Atlantic salmon (2024). However, the new techniques of genome editing (gene editing, such as CRISPR) are being used to genetically engineer other pigs and fish, and other animals, for food.
US approves GM pig
The US Food and Drug Administration (FDA) has just approved a gene-edited pig for human consumption. The company’s Chief Operating Officer, Matt Culbertson, says that the GM pig could be on the market as soon as next year. However, it will likely be a few years before it is introduced, if at all. If the GM pigs are produced, the meat will not require labelling the US or Canada.
This GM pig was developed by the UK-based “Pig Improvement Company” or PIC which is owned by Genus, one of the biggest animal genetics companies in the world. The company says it is also seeking approval in Canada and in other US export markets such as Mexico, China and Japan.
The company has genetically engineered the pigs using the gene editing technique of CRISPR to make the pigs resistant to the common virus PRRS (porcine reproductive and respiratory syndrome). CRISPR was used to ‘knock out’/delete a section of DNA that produces a protein that the PRRS virus uses to enter and infect the pig: the CD163 receptor on pig cells. Read more below about how CRISPR-Cas can be used to delete genes.
The company claims that the GM pigs are resistant to most, but not all, strains of the PRRS virus circulating today. This means that infections in the genetically engineered pigs may continue. This RNA virus undergoes rapid and constant genetic change such that the success of current vaccines to provide solid immunity across all strains has been impossible to demonstrate.
PRRS and other diseases thrive in the crowded conditions of large intensive livestock operations. Much like the development of the “Enviropig”, many gene edited animals will be developed as attempted techno-fixes for problems caused by factory farms.
Other GM pigs
In 2020, the US FDA approved a different gene-edited pig called the “Galsafe” pig, for use in both medicine and food. Those pigs were genetically engineered to eliminate the sugar alpha-gal which makes pig organs unsuitable for transplantation into humans and can cause allergic reactions in some people. The company, Revivcor. does not sell the pigs as food but reportedly provides GM pig meat on request.
More patents on GM animals
Every year, the number of international patent applications for genetically engineered vertebrates intended for food is increasing. From 2020 to 2024, patent offices reviewed around 50 patent applications, and the European Patent Office granted at least three patents.
Most of these international patent applications were for genetically engineered fish (12) and poultry, pigs and ruminants (9 each). The objectives were to make changes in the reproductive capacity of the animals (14), the further development of gene editing processes and suitable stem cells (12), increased production (7) and resistance to pathogens (6).
The patent applications include:
- Fish – for sterility, faster growth, and fewer bones;
- Cattle, pigs and poultry – for sterility, sex determination, higher performance, and resistance to viruses;
- Elephants – for an appearance modelled on that of mammoths using Artificial Intelligence and gene editing.
In 2023, the Universities of Edinburgh, Maryland and Washington were granted a patent for pigs and cattle that do not produce their own sperm cells and instead are intended to inherit traits from other animals. For this purpose, corresponding germline cells can be transplanted into the animals.
Read more in the new report from Testbiotech (Germany), Use of genetic engineering in farmed vertebrates: a critical assessment.
“Knocking out” genes
Gene editing offers powerful new tools for genetically engineering animals.
With CRISPR-Cas, gene scissors (nucleases) can be used to ‘knock out’ genes. To do this, the nuclease (Cas) causes a break in the DNA strand and then leaves it to the organism’s own cellular repair mechanisms to repair the damage. However, the nuclease can be used to prevent the repair processes from restoring the original gene function: genetic scissors that are ‘programmed’ to ‘cut’ a specific DNA sequence can also recognise the sequence and cut it again after successful repair, so that the repair becomes faulty and the original gene function is lost.
A DNA double-strand break (DSB) is a serious form of DNA damage in which both strands of the DNA double helix are severed. Cells have their own special internal repair mechanisms to repair DSBs. If only one strand of the DNA double helix is affected, the other (complementary) strand serves as a template for the repair. This is not the case with DSBs, which is why their repair is much more difficult. One possible consequence of DSBs is faulty repair, resulting in a new gene variant (mutation) at the target site in the genome. Depending on the location and result of the change, the biological effect – intentional or unintentional – can have very different consequences.
Read more in the new report from Testbiotech (Germany), Use of genetic engineering in farmed vertebrates: a critical assessment.
Read more in our report about genome editing or see our webpage cban.ca/gene-editing