Conquest
Fall 1995

A Thriving Community

Chimpanzee breeding and research program run by M. D. Anderson provides vital biomedical research partners

By Mary Jane Schier

They have names like Allie, Budda and Cookie. They are so playful--and so happy in their environment--it is easy to forget that they have a valuable role in biomedical research.

Allie, Budda and Cookie are among the chimps who live at the M. D. Anderson Science Park's Department of Veterinary Sciences near Bastrop, Texas. All are helping scientists find solutions for many human health problems, including a vaccine for the virus that causes the world-wide killer disease AIDS.

M. D. Anderson is one of several institutions around the country participating in the National Chimpanzee Breeding and Research Program. The M. D. Anderson program recently received a very favorable review and was awarded $3.1 million to support it for the next five years.

"Because the chimp's immune system is comparable to humans, much of the molecular information learned from chimps is assisting scientists in understanding the fundamental mechanisms of hepatitis, some infectious diseases and the human immunodeficiency virus (HIV) that causes AIDS. These same molecular functions are also important to cancer. Over time, our goal here is to contribute knowledge to the understanding of cancer," says Dr. Michale E. Keeling, ch airman of the Department of Veterinary Sciences since it was established in 1975 as one of two M. D. Anderson Science Park units.

Chimps are the only non-human primate that can become infected with HIV, yet they don't get sick. Many investigators believe if they could figure out the basic molecular factors that protect the chimps, they could apply that wisdom to people.

"We have about a dozen chimps dedicated to AIDS studies. Four of these who were given HIV injections in 1988 continue to be observed in an isolation area. Another 35 to 40 chimps are in an HIV reserve group; these adult animals already have participated in hepatitis and other research and could be available for AIDS vaccine studies if they are needed," Dr. Keeling explains.

Eight chimps between two and four years old left the Department of Veterinary Sciences last summer for another institution, where they are involved in a study to design a vaccine for respiratory syncytial virus (RSV). This virus is often fatal for infants and young children. When the study is finished, the chimps will be returned to the Department of Veterinary Sciences, closely watched in quarantine for six months and then reintegrated in a larger group of animals.

Chimpanzees share about 99 percent of humans' genetic makeup. Even though they are our closest relative on the evolutionary scale, only a small number are used in biomedical or behavioral research. Due to their scarcity, they are almost never sacrificed.

Extraordinary efforts have been made during the past two decades to preserve and protect chimpanzees. Dr. Keeling says chimps who live in the wilds are considered endangered while those in captivity are classified as threatened. An international trade agreement prevents importing chimps from the wilds to use in research.

"This is why it is vital to maintain a domestic population of chimpanzees that is self-sustaining over generations," he notes.

In addition to the chimps designated for research, the M. D. Anderson program combines breeding, rehabilitation and enriched housing in outdoor corrals that simulate the animals' natural environment. About 90 chimps--ranging in age from a few months to more than 30 years--live in social groups divided among eight corrals. Besides their physical well-being, considerable emphasis is placed on their mental health.

"Our facilities provide a unique balance of a simulated natural environment and enough controls that allow us to retrieve the animals for health care and limited research studies. I believe the most valuable lesson we've learned is that we could re-establish survivability of captive chimps," Dr. Keeling notes.

Looking back to when he began designing the program in 1976, Dr. Keeling says his original aim was to give future chimps enough space and independence to thrive while assuring regular access to them. Six adult chimps arrived the following year to start the program. Before long, breeding was under way; since then, 132 chimps have been born. The production part of the chimp program has been so successful that several adult females now need birth control.

"We were the first group to try implantable contraceptives on a large scale in the chimps about three years ago," says Dr. Rick Lee, assistant professor of comparative medicine, who oversees the comprehensive health care for the animals.

Dr. Lee uses ultrasound to confirm that the contraceptives remain in place and to track normal pregnancies. The chimps have regular immunizations for tetanus, polio and rabies. During physical examinations, they have their teeth cleaned, blood drawn, urine collected, weight measured, body fat determined and blood pressure monitored.

When a new mother chimp needed blood replaced after delivery a few weeks ago, Dr. Lee and his assistants collected blood from other chimps for the transfusion. He also did a recent spinal tap on an elderly chimp who had a slipped disc.

"Obesity can be a problem as the chimps live longer and overeat if allowed. So we've cut back on their fat intake and increased their fiber, fresh fruits and vegetables. Just as with people, cardiovascular disease is a common problem among the elderly chimps," Dr. Lee says.

Dr. Mollie Bloomsmith, chief of the Section of Behavioral Sciences, has pioneered studies of chimp behavior since joining the M. D. Anderson faculty nine years ago. Much of her work focuses on feeding enrichment strategies that allow the chimps to spend more time foraging for food as they would in the wilds.

Some of their favorite foods are coconuts, grapes, corn-on-the-cob and watermelon. The more time they spend hunting for food and eating it, the less time they engage in aggressive or other undesirable behavior.

"Chimps are very smart animals with a huge capacity for learning and solving problems. In addition to devising food puzzles and introducing them to foods that take considerable time to process, we try to challenge their cognitive abilities and provide more sensory stimulation. They like to play with big pieces of brown wrapping paper, bamboo branches and balls. Many will watch video tapes and TV cartoons. In the near future, we plan to give them computer games a nd see what they will learn," Dr. Bloomsmith explains.

She says healthy food rewards are used to motivate the chimps to move from one part of the corral to another to facilitate maintenance. Some animals have been trained to urinate in a cup when samples are needed for pregnancy tests. Other chimps have been taught to put an arm through a device that allows blood to be collected for various medical tests. Their rewards may include apples, oranges, kiwi, yogurt and friendly interactions with their caregivers.

Allie is a six-year-old chimp born with a serious form of diabetes. She's been trained to sit still for blood-drawing and insulin injections, after which she enjoys her anticipated sugar-free drink, deposits the paper cup in a wastebasket and washes her hands.

Considerable attention has been devoted to helping the captive mother chimps rear their infants in situations similar to the wilds. Over the years, those few babies who were rejected by their mothers have been raised in a nursery setting with other chimps and with two dogs for companions.

"The mother-infant relationship is critical to future propagation. One key reason for our successful program involves the way we've paid attention to breeding and evaluated the population dynamics of these chimps. It's been a fascinating experience to plan such a specialized program, build the facilities and utilize them as we envisioned. I think we'll be prepared to take advantage of most any research opportunities that come along," Dr. Keelin g says.