Genetically engineered pigs resist the foot-and-mouth disease virus
Pigs can be engineered to be less susceptible to a virus that causes devastating outbreaks in livestock.
Foot-and-mouth disease regularly causes serious outbreaks in livestock. The virus that causes the disease can infect cattle, pigs, sheep, goats, and many species of wild animals; the disease is also highly contagious and spreads very quickly and easily. To control the spread of foot-and-mouth disease, farmers must often kill entire herds of animals that have been exposed. Wild animals that can spread the virus may also be killed in an effort to stop the spread of the disease.
Vaccines that protect against foot-and-mouth disease are available and are often used to help prevent the spread of the disease. However, once an outbreak of foot-and-mouth disease begins it may be too late for vaccines to stop its spread. This is because the vaccines can take about a week to provide protection, and by that time an exposed animal may already be very ill.
Previous work conducted in 2010 reported that mice could be genetically engineered to produce short stretches of RNA molecules that can switch off genes from the foot-and-mouth disease virus. Compared with normal mice infected with the foot-and-mouth disease virus, the genetically engineered mice showed little sign of the disease in their bodies. Now, Shengwei Hu, Jun Qiao, Qiang Fu and co-workers — including some of the researchers involved in the 2010 work — have genetically engineered pigs in the same way. The experiments show that when cells from these pigs are exposed to the foot-and-mouth disease virus in the laboratory, the virus grows much less than normal.
Next, Hu, Qiao, Fu and co-workers injected genetically engineered pigs and non-genetically engineered pigs with the virus. All of the normal pigs developed severe symptoms very quickly, including the disease’s characteristic mouth and foot sores. Additionally, examinations of these pigs’ cells showed signs of the disease. But the genetically engineered pigs did not become seriously ill and their cells showed little sign of the disease. Some of the genetically engineered pigs developed a few sores but these sores appeared much later than normal. So far, the results suggest that it may be possible to develop pigs that are resistant to foot-and-mouth disease. Hu, Qiao, Fu and co-workers will next determine whether or not the genetically engineered pigs can pass the foot-and-mouth virus on to other pigs and livestock.
To find out more
Read the eLife research paper on which this story is based: “Transgenic shRNA pigs reduce susceptibility to foot and mouth disease virus infection” (June 19, 2015).
Read a commentary on this research paper: “Foot and mouth disease: Virus-resistant pigs might help to stem next outbreak”
eLife is an open-access journal that publishes outstanding research in the life sciences and biomedicine.
