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U.S. Department of Health and Human Services

Animal & Veterinary

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CVM Participates in PEW Initiative Meeting on Transgenic Animals

by Wendelyn Jones Warren, Ph.D.
FDA Veterinarian Newsletter January/February 2003 Volume XVIII, No 1

Transgenic animal research is rapidly evolving to-ward practical and commercial applications. Two approaches for animal biotechnology include animals genetically engineered for "biopharming" and animals genetically engineered for improved agronomic traits. Biopharming, in general terms, applies not only to the harvesting of drugs, biologics, and industrial substances from milk, blood, or other tissues but also to animals engineered for tissue donation to humans, i.e., xenotransplantation. Animals with improved agronomic traits may exhibit increased feed efficiency and/or decreased time to market weights, animal disease resistance, or changes in the qualities of food derived from the animals. As stated in the White House Office of Science and Technology Policy Case Studies (available at www.ostp.gov), the FDA/CVM has proposed regulating transgenic animals under the "new animal drug" provisions of the Federal Food, Drug, and Cosmetic Act.

CVM scientists participated in a two-day workshop on transgenic animals, "Biotech in the Barnyard: Implications of Genetically Engineered Animals," as a means to interact with the interested public and to meet with leading researchers in the field. This multidisciplinary workshop was sponsored by the Pew Initiative on Food and Biotechnology. In attendance were representatives from industry, academia, consumer groups, animal welfare groups, environmental groups, policy leaders and opinion makers.

The transgenic animal workshop, held over two days (September 24-25) in Dallas, TX, was followed by the one-day symposium, co-sponsored by CVM, on animal cloning: "Animal Cloning and the Production of Food Products - Perspectives from the Food Chain." (The audio web cast recording of the both conferences can be accessed at http://pewagbiotech.org/events/0924/.)

The transgenic animal workshop was divided into four panels of three speakers each. At the completion of each panel, audience members were encouraged to ask questions of the panelists. It is worth noting that the panels were designed to have a mix of perspectives within each grouping. Additionally, after the completion of the day's panel discussion, all workshop participants were split into breakout groups for further exploration of the topics presented.

The first topic on the agenda was a review of the technology, "The ABCs of Transgenic Animals: Current and Future Applications," by Dr. Neal First. Dr. First's talk served as both a historical review of the field of transgenics and an overview of the scientific process of transgenesis. His talk noted the prevalent use of murine models in current biology labs and went on to discuss in detail efforts to bioengineer pigs lacking the 1,3 galactosyl transferase enzyme. This enzyme is responsible for the 1,3 galactosylated antigens which prohibit the successful xenotransplantation of swine organs to humans.

This opening talk led into the first panel on "Animal Matters: Social, Ethical and Animal Welfare Consideration." Participating in the panel were Drs. William Velander, Gary Comstock and Joy Mench. These three speakers individually and collectively addressed how transgenic technology fits with the public views on animals.

Dr. Velander's talk emphasized the human medical benefit of protein therapeutics made in genetically engineered animals. He emphasized the ability of researchers to produce prodigious amounts of human proteins in the mammary gland of a transgenic animal only during lactation so that it is naturally exported into the milk, just as any other milk protein. He noted that this process is typically not harmful to the host animal and yet can produce a complex protein suitable for human therapy. The specific example he cited was transgenic swine genetically engineered to produce Factor IX used in the treatment of hemophilia in humans.

Bioethicist Dr. Comstock spoke about what ethics should govern the treatment of transgenic farm animals. He suggested that while it was common to view transgenic animals as valuable production machines, it may be more beneficial to society that animals be viewed as beloved pets, which provide for sick humans and give us their lives in service. His take-home point was that transgenic animals are subjects of the scientists' own making and thus obligations to transgenic animals are greater than the obligations to those animals not subject to bioengineering techniques.

Dr. Mench discussed animal welfare issues. She noted that the lack of an animal welfare standard in conventional agriculture means there is no clear benchmark against which to measure the welfare of transgenic barnyard animals. This is even further complicated as many of the technologies used to create transgenic animals are also already used in conventional agriculture.

While the first panel discussed transgenic animals in the barn, the second panel discussed transgenic animals outside the barn. The second panel, "Beyond the Barn: Ecological and Human Health Considerations," was made up of three academicians, Drs. Bill Muir, Jim Murray, and John Coffin.

In discussing the ecological risk issues associated with transgenic animals, Dr. Muir argued that scientists could estimate the risk posed by a particular transgenic animal prior to release by analyzing the likelihood the transgenic animal could become established in the environment. This process includes evaluating four fitness components, such as fertility, fecundity, age of sexual maturity, and mating success.

Dr. Murray discussed food safety concerns related to transgenic animals. In addressing whether transgenic animals can inadvertently contain new food allergens and toxins, Dr. Murray stated that if the transgene is a totally new gene that has never been part of the diet, it should be carefully assessed. He stated that the magnitude of the food safety risk also depends on the process used to generate the transgenic animal. For instance, in animals created through microinjection, it is highly improbable that the insertion could activate the expression of a gene that produces a novel toxin or allergenic compound since only about 2% of an animal's DNA actually codes for genes.

Dr. Coffin expanded the human safety discussion to include direct human health considerations. He noted that the use of transgenic farm animals poses some novel risks of infectious disease in humans depending on the technology used. Dr. Coffin noted the use of antibiotic resistance marker genes in the generation of transgenic animals may contribute to the reservoir of resistant pathogens. Additionally, if used to generate transgenic animals, viral vectors could potentially recombine with a latent virus buried in the animal's genome.

In presenting the potential impacts of transgenic animals on the environment and on humans, panelists emphasized the low risk and relative safety of transgenic animals especially if under Federal oversight.

While the first day addressed the impacts of transgenic animals inside and outside the barn, the second day moved to impacts of the technology in agricultural marketing and then finally to Federal oversight of the transgenic animals.

Dr. Cecil Forsberg led off the third panel of the workshop by presenting a case study on the economics and marketing of environmentally friendly transgenic pigs. Enviropigs, a specific type of transgenic pigs, produce manure that is lower in phosphorus and thereby cause less environmental pollution.

The consumer perspective on marketing transgenic animals was presented by Jean Halloran. She noted the divide between what scientists and industry are discussing and what the public is aware of and discussing. Ms. Halloran urged the FDA to educate the public on transgenic technology and to engage in continued public discussion on both legal and ethical issues.

Dr. Lawrence Schook explained how advances in genomics might be able to address many of the health, safety, and ethical concerns that have consumers worried. More sophisticated techniques will allow exact placement of the transgene into the DNA, mitigating the dangers of accidental gene activation or unintentional mutations caused by microinjection.

The final panel of the workshop provided an analysis of the laws and regulations governing the use of transgenic animals in the U.S. Presenting in the "Institutional and Legal Background" section were Fred Degnan, Michael Taylor, and Bud Locklear. A number of Federal regulatory agencies and statutes come into play when discussing transgenic animals.

However, none of them specifically address transgenic animals since many regulations were enacted before technology had evolved to generate transgenic animals. All speakers noted that the predominant Federal agency involved in the oversight of transgenic animals was the Food and Drug Administration. Fred Degnan and Michael Taylor described, evaluated, and made recommendations regarding how the Agency can maintain the public's trust and ensure food safety, animal safety, and environmental safety.

In conclusion, the CVM scientists found the presentations and the workshop as a whole very informative. The presentations stimulated some lively discussions among the attendees. Through attending the meeting, the participating CVM scientists had a much stronger grasp of the concerns important to various stakeholders. This type of public interaction early in the regulatory process for transgenic animals will help regulatory scientists respond to stakeholders with understanding and ensure the best science-based decision process.

Dr. Warren is a pharmacologist with CVM's Division of Human Food Safety.