GENEWATCH
 
MONITORING ANIMAL PRODUCTS AND FEEDS WITH DNA BARCODING
By CRG staff - interview with Haile Yancy
 

from GeneWatch 26-5
Nov-Dec 2013

Haile Yancy, PhD, is a senior research biologist at the U.S. Food and Drug Administration's Center for Veterinary Medicine.

 

GeneWatch: Can you tell me a bit about how DNA barcoding relates to your work at FDA? How was it first used for monitoring animal products or feeds?

Haile Yancy: We started out using it for preventing mad cow disease. The issue with mad cow disease is that ruminant material - bovine, sheep, or goat - is not allowed to be put into animal feeds and fed back to cows, because that's how the disease spreads. So we didn't use DNA barcoding per se to develop those assays, but we used those DNA sequences that are unique in barcoding and designed species-specific primers which we use to make sure that no ruminant material is in animal feeds.

More recently, the Chicago office asked for our help identifying potentially mislabeled game meat and potentially mislabeled pet foods. These concerns are similar to the concerns with seafood mislabeling, where someone sells one product but labels it as something else so you can charge a higher price. With pet foods, there was concern about, for example, someone charging a higher price for gourmet duck pet food - was it actually duck meat?

It's the same thing for the game meats. FDA has jurisdiction over game meats, and they wanted to make sure that if a company is selling, let's say, bear steaks - which are legally sold - are they actually bear steaks?

I'm trying to imagine someone testing a piece of dry dog food. Where are the samples collected to make sure you have enough to get a DNA barcode?

We can extract DNA from really any material now. If it's wet dog food, dry dog food ... we've actually done a lot of work with pet jerky, too. It's been on the news recently, there's concern about dogs getting sick from pet jerky - we did the testing of the jerky to make sure it is what's on the label. So really any material we have, we can extract DNA from.

But when we talk about animal feed that has been rendered, it can be very difficult to create a full-length barcode. So my colleague Yolanda Jones is not only validating full-length barcodes, but also looking at what they call "mini barcodes." Whereas regular barcodes are about 650 base pairs, minis are only 100 base pairs. The materials we look at have sometimes been degraded, whether by cooking or rendering or just sitting out on a dock somewhere, which makes it very difficult to create an amplified product of 650 base pairs, but you can still create a product of 100 base pairs and use the same approach and still identify what that species is.

If you weren't using DNA barcoding, what's the alternative? For example, how else would you identify ruminant material in feeds?

Currently, the gold standard for making sure there's no ruminant material in animal feeds is microscopy. You have a microscopist who actually looks at the particles in the feed to determine whether it contains animal material. The problem with that is if you find, for example, a hair in the feed, it doesn't tell you if this hair is from a cow, a sheep, or a pig. So although microscopy is the gold standard, it has a very difficult time identifying species. So you have to fall back on these molecular methods, because if there's hair there, we need to determine where it's from. That's what's important: Not just determining whether there's animal material in the feed, but is this material from a ruminant species?

Are there other uses of DNA barcoding at FDA currently in use or planned besides the ones you have mentioned?

We recently had a group that was looking at prevention of infectious diseases transmitted to humans by bushmeat. People had been bringing back exotic meats, or bushmeat, from other countries. There's an executive order that the President just signed to combat wildlife trafficking, and one of the ways we're doing that is putting together a national smuggling prevention network to prevent the illegal importation of bushmeat into the United States. Part of that effort is to identify which species are brought into the U.S. as bushmeat, so part of what FDA has been tasked with is creating a DNA barcode database to use for this. If you have a piece of meat come in, it may not have the distinguishing characteristics that tell you "this is a monkey" or "this is an alligator;" so what we'll do is barcode that, match it against the database, and once you figure out what kind of bushmeat that is, you can associate it with risk. Specific bushmeats carry a specific risk - for example, primates can carry herpes virus or anthrax virus. It's very difficult to establish risk without understanding which species it is. We're part of a group working on this that includes the FDA, the U.S. Department of Agriculture, Customs and Border Protection, the Center for Disease Control, Fish and Wildlife Service, and hopefully including state and local governments.

That's pretty expansive!

Yes, it's a fairly new group of individuals, but we've got the wind behind our back with the presidential executive order. Some of these diseases are very nasty, and it's something we hope can be prevented with all these agencies working together. We're working very quickly to develop a method of barcoding so that when someone confiscates material at the border, they will be able to know what it is and make sure the risk is minimized.

Are you using existing reference databases for this, like the Barcode of Life?

Yes - one of the things we recognized very early is that it would be virtually impossible for the FDA by themselves to get the materials to build these reference databases. I've been working with Barcode of Life for over 12 years now. Their goal is to prevent the illegal importation of endangered species, so what we've done is piggyback on that, because if you look at the list for bushmeats and the list for endangered species, there is an overlap of common species. We don't have the infrastructure to go to Africa and actually get samples of lions and elephants, so we have access to their specimens to help populate our database.

Do you see any new uses for DNA barcoding in the pipeline or farther down the road?

Because the technology is there to determine species of origin, you can see a shift in making sure, both on the producer and consumer side, that consumers get what they pay for - not only for economic reasons, but also for safety.

One thing we've been working on is concerns about heparin (an anticoagulant) being made from non-porcine material, specifically from cow material. The method we've developed for testing this is actually a modification of our assay for finding bovine material in feeds. That's the safety aspect, but there's also a religious aspect, because if you don't eat pigs you're concerned about heparin being made from porcine material, so you want the opposite - you want to make sure your heparin products are derived from cow rather than pig material.

I see a lot of other uses for this for everyday things that we take for granted. For instance, if you've read the papers, there have been issues with food supplements being mislabeled. I can see DNA barcoding being used more and more as two things happen: Firstly, developing more efficient ways of extracting DNA and being able to sequence it; and secondly, making sure that the cost goes down. As those happen, you'll see a large application. And consumers are becoming more and more aware of things being substituted and mislabeled - like the grocery store that found out some of the meat it was selling was not beef, but horse. More and more consumers are asking: Am I buying what I think I'm buying? And it matters from both an economic and a safety point of view. It's way off in the future, but one of the long-term things we're trying to work on, with Barcode of Life, is a handheld device that can do all these things. We're heading in that direction.

 
 
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