Youyou Tu

Three researchers have won the 2015 Nobel Prize in Physiology or Medicine for discoveries related to parasitic diseases.

One half of the prize was awarded to Youyou Tu for discoveries concerning a novel therapy against malaria—artemisinin.

The other half of the prize was awarded to William C. Campbell, PhD, and Satoshi Ōmura, PhD, for their discoveries concerning a novel therapy against infections caused by roundworm parasites.

Drs Ōmura and Campbell discovered the drug avermectin. A derivative of this drug has lowered the incidence of river blindness and lymphatic filariasis and demonstrated efficacy against other parasitic diseases.

Artemisinin

Before artemisinin came into use, malaria was treated with chloroquine or quinine—with declining success. By the late 1960s, efforts to eradicate malaria had failed, and the disease was on the rise.

At that time, Tu turned to traditional herbal medicine to tackle the challenge of developing novel malaria therapies. From a large-scale screen of herbal remedies in malaria-infected animals, an extract from the plant Artemisia annua emerged as an interesting candidate.

However, the results were inconsistent. So Tu revisited the ancient literature and discovered clues that guided her in her quest to extract the active component from Artemisia annua. Tu was the first to show that this component, later called artemisinin, was effective against the malaria parasite in animals and humans.

Artemisinin is now used in all malaria-ridden parts of the world. When used in combination therapy, it is estimated to reduce mortality from malaria by more than 20% overall and by more than 30% in children.

Avermectin

The discovery of avermectin began with Streptomyces, bacteria that live in the soil and are known to produce agents with antibacterial activities.

Dr Ōmura isolated new strains of Streptomyces from soil samples and cultured them in the lab. He selected about 50 of the most promising cultures to analyze for their activity against harmful microorganisms. One of these cultures turned out to be Streptomyces avermitilis, the source of avermectin.

Dr Campbell acquired Dr Ōmura’s Streptomyces cultures and explored their efficacy. Dr Campbell showed that a component from one of the cultures could combat parasites in domestic and farm animals.

The bioactive agent was purified and named avermectin. It was subsequently modified to a more effective compound called ivermectin. Ivermectin turned out to be effective against a variety of parasites, including those that cause river blindness and lymphatic filariasis.

Today, ivermectin is used in all parts of the world that are plagued by parasitic diseases. The drug has proven effective against a range of parasites and has limited side effects. Thanks to ivermectin, river blindness and lymphatic filariasis are on the verge of eradication.

About the winners

Youyou Tu was born in 1930 in China. She graduated from Beijing Medical University in 1955. Tu has worked at the China Academy of Traditional Chinese Medicine since 1965. She has been chief professor there since 2000.

William C. Campbell was born in 1930 in Ramelton, Ireland. He received a BA from Trinity College, University of Dublin, in Ireland in 1952. He received a PhD from the University of Wisconsin in Madison, Wisconsin, in 1957.

From 1957 to 1990, Dr Campbell was with the Merck Institute for Therapeutic Research, from 1984 to 1990 as a senior scientist and director for assay research and development. Dr Campbell is currently a research fellow emeritus at Drew University in Madison, New Jersey.

Satoshi Ōmura was born in 1935 in the Yamanashi Prefecture, Japan. He received a PhD in pharmaceutical sciences in 1968 from the University of Tokyo and a PhD in chemistry in 1970 from Tokyo University of Science.

Dr Ōmura was a researcher at the Kitasato Institute in Japan from 1965 to 1971 and a professor at Kitasato University from 1975 to 2007. Since 2007, Dr Ōmura has been a professor emeritus at Kitasato University.

Trio wins Nobel Prize for parasite-related discoveries