A research team at the Roslin Institute is using advanced genetic techniques to engineer pigs that are more resilient to deadly virus infections. The study at the University of Edinburgh is aimed at assessing whether changing the pigs’ genetic code at a precise point in their DNA affects their susceptibility to African swine fever (ASF). The next step will be to test how altering the pigs’ genes affects transmission of the virus and whether the animals fare better after infection than standard farmed pigs.
The animals have been created using an advanced genetic technique called “gene editing” to modify individual letters of the pigs’ genetic code. The change is designed to dampen the immune system’s overreaction to the virus, which is responsible for the devastating effects of the disease.
ASF is spread by ticks. When standard farmed pigs are infected, they become ill very quickly and die. In contrast, warthogs and bush pigs show no disease symptoms when infected. One of the pig genes associated with African Swine Fever Virus infection is called RELA. The role of this gene is to activate the immune response.
Warthogs and bush pigs carry a different version (or allele) of the RELA gene to that found in domestic pigs. This difference may make them resilient to ASF. The gene differs from that carried by domestic pigs that you would find on a farm by only a few letters of the genetic code. However, this may have a huge impact on the outcome of infection.
Roslin scientists have produced pigs which have a single letter of their genetic code altered. These animals produce a shorter version of RELA, which lacks a domain involved in the immune response. The team had created a separate group of pigs that have changes at several sites in their RELA gene, to make it the identical to the version that is found in the warthog.
All of the changes that have been introduced could have occurred spontaneously in nature. Researchers hope that the genetic changes will make the animals more resilient to infection with African swine fever virus, but they still need to test this in controlled trials.
There has never been an outbreak of ASF in the UK, yet the virus has recently started spreading throughout Eastern Europe. There are fears that it could reach British farms.
The team plans to use the same gene-editing techniques to produce cattle, chickens and sheep that are resistant to infections; however, this research is at a much earlier stage.
Professor Bruce Whitelaw, head of Developmental Biology at the University of Edinburgh’s Roslin Institute, said, “We have used a gene-editing technique to change individual letters in the pigs’ genetic code, to speed up a process that occurs spontaneously in nature.
“Our goal is to improve the welfare of farmed pigs around the world, making them healthier and more productive for farmers.”