Editing isn’t just for writers anymore.
Animal scientists have found a way to edit genes and help fight disease while improving production.
Gene editing is a technology that was first developed in the late 1990s, but has developed more technically in recent years, according to Chris Hostetler, National Pork Board director of animal science.
“The actual gene editing is easy, rapid and fairly inexpensive. It’s the research that is more expensive and takes time that makes the process longer,” Hostetler said.
Gene editing works by first identifying a targeted DNA strand for a specific trait or disease. A specifically designed synthetic guide molecule finds the target DNA strand, then an enzyme cuts off the target DNA strand and replaces it with a healthy one.
Pork producer Randy Spronk, of Edgerton, Minnesota, said gene editing is a way to get rid of harmful diseases such as Porcine Reproductive and Respiratory Syndrome. “PRRS has been a devastating disease in the U.S. pork industry, in which vaccination hasn’t been very effective and air filtration has been a slightly effective tool.
“University of Missouri researchers have used gene editing to develop a PRRS resistant pig. We want to be able to use this technology to help eradicate this disease,” Spronk said.
Gene editing mimics natural selection, while speeding it up and being more precise in the process.
Hostetler said gene editing is really like any breeding technologies that are used, except better.
The process
Gene editing can happen in more than one way, according to Hostetler. Scientists synthesize the sequence in a laboratory so researchers simply order the sequence they want and the desired DNA sequence is shipped to them.
“Scientists can make gene edits directly in an individual animal to address a disease or improper metabolic function within that animal. This is actually how they are doing it in human medicine,” Hostetler said. “To do this, they harvest cells from the animal, make the gene edit and then inject them back into the tissue where they re-establish themselves and now function normally. In this case, the gene edit dies with the animal and is not passed to the next generation.”
Scientists can also directly edit developing embryos. In this case, the edited gene is incorporated into all cells in the embryo. For example, say an animal’s muscling profile needs to change.
“They gene edit the myostatin gene so that it wouldn’t ‘turn off’ muscle growth as it normally does,” Hostetler said.
The myostatin gene is present in all cells, but in normal animals it is only activated in muscle cells. Because the gene is in all cells this means that it is also present in sperm and eggs and in this way it can be passed down to the next generation, he explained.
“This means that the offspring will carry the gene edited myostatin gene just like their parents. In most cases this is how we do it in livestock,” Hostetler said. “We don’t typically use this method in humans because of the ethical implications associated with making a decision that affects future generations of humans.”
Since the genetic sequence for the pig was published in 2012, Hostetler said it is easier to make improvements and changes in genes.
“We would originally look at a disease through research. In this research we would infect pigs with the disease and had a small percentage of hogs (7 percent) that weren’t affected by the disease,” Hostetler said. “This is why it can be looked at as an improvement practice.”
Ethics
Since gene editing is just an improvement of the animal, similar to natural selection through breeding programs, acceptance should be more easily found.
Charlie Arnot, CEO of the Center for Food Integrity said once gene editing is widely recognized and society realizes the implications it can have on human health, and plant and animal production, it should become accepted.
“The acceptance of promising innovations like gene editing hinges on how agriculture and technology developers approach the conversation—now and in the long-run,” said Arnot. “Without a doubt, gene editing can deliver significant benefits and solve challenges in society and food production. It is imperative that those using gene editing work to earn the trust of consumers and food system stakeholders so these benefits can be realized.”
The Center for Food Integrity has developed the Coalition for Responsible Gene Editing in Agriculture to provide communication materials and training to people in research, developing and communicating about gene editing in food and agriculture.
This coalition is committed to earning trust in gene editing to produce safe, wholesome and affordable food in a sustainable manner, using the values of food safety, sustainability, environment, animal well-being, transparency, science, economics, viable consumer trust and respectful collaboration.
Arnot said the group has two challenges. The first is to get the group of stakeholders to build guidelines for regulatory use for gene editing.
“People want to know that gene editing is used correctly and that the basic principals of the technology are used responsibly,” Arnot said.
The second is to build a toolkit encouraging communication about the importance of gene editing.
“We need to be sure to get the key messages out about gene editing and why its is important for the future of the crop and livestock industries,” Arnot said.
Jennifer Carrico can be reached at 515-833-2120 or [email protected].
