“All animal models are abstractions,” Yale immunologist Richard A. Flavell has said. “You’re not studying humans but a process in animals that is relevant to humans.” Still, Flavell and his researchers work almost entirely with mouse models to discover why the human immune system sometimes fails to protect the body from foreign invaders, leading to such debilitating autoimmune diseases as Type I diabetes, rheumatoid arthritis, psoriasis, multiple sclerosis, and Crohn’s disease.

By the ‘80s, the results of Flavell’s research with genetically engineered mice were notable — a vaccine for Lyme disease among them — but there had to be a better way, he believed. Together with colleagues, he set to work building a better mouse model, one with human immune cells that would make it possible to safely and reliably assess potential vaccines and therapies prior to human trials. Today, “humanized” mice are in wide use in scientific research, promising hope for the development of vaccines for HIV, multiple sclerosis, and other autoimmune disorders.

Born in the Essex region of England, Flavell admits he “was a very bad pupil, [who] lacked motivation and found everything boring.” It was a chemistry teacher who broke through his intellectual malaise, inspiring him to do chemistry experiments; this led him to combine this interest with his fascination with natural history.

As assistant professor at the University of Amsterdam, he made the notable discovery that mammalian DNA contains introns, segments of genetic code that break up a gene into pieces. He continued his gene studies back in England, as head of the Laboratory of Gene Structure and Expression at the National Institute for Medical Research at Mill Hill. He later became founding Chairman of the School of Medicine’s Immunobiology department at Yale. Today, the Sterling Professor of Immunobiology and HHMI investigator directs one of the top immunology programs in the country, as well as his own lab.