In 2001, an epidemic of foot and mouth disease in the UK resulted in the destruction of over six million livestock, restrictions on international trade, and economic costs in excess of £3 billion. Foot and mouth disease is most common in developing areas of the world, such as parts of Asia, Africa and the Middle East, and an outbreak of the disease in animals raised as food resources in such areas can have a devastating effect on economic growth. Research just published reports the results of experiments on genetically engineered pigs that could have broad implications for the control of the disease.
The virus that causes foot and mouth disease (FMD) comes in seven types, each of which requires a specific vaccine for immunization. The Chinese team focused on a protein called VP1 that is variable across all different FMD viruses. VP1 is part of the virus capsid, a three-dimensional array of proteins that is involved in receptor binding and entry into host cells. The researchers looked for the small RNA that was best able to stop the replication of the FMD virus. They then integrated the gene coding for this small RNA into the genome of single pig cells. FMD virus was almost completely inhibited from growing and dividing inside the cells derived from transgenic pigs.
This work is a proof of concept for the use of RNA interference technology to produce transgenic livestock with increased resistance to virus infection. Although this technology could potentially increase food security, it also faces major challenges since, to date, neither the Food and Drug Administration in the United States nor the European Food Safety Authority have approved genetically engineered animals for human consumption. A global consensus on the regulation of genetically engineered organisms has not been reached and each country adopts policy at a national level. However, the governments in a number of countries – including Argentina, Brazil and China – view transgenic products as a way to resolve food security issues. Such countries have simpler protocols for the approval of transgenic products, which might allow transgenic animals to be approved for human consumption.