BioEd Online

Three scientists who developed therapies against parasitic infections have won this year's Nobel Prize in Physiology or Medicine.

The winners are: William C. Campbell, a microbiologist at Drew University in Madison, New Jersey; Satoshi ?mura, a microbiologist at Kitasato University in Japan; and Youyou Tu, a pharmacologist at the China Academy of Traditional Chinese Medicine (now known as the China Academy of Chinese Medical Sciences) in Beijing.

In the 1970s, Campbell and ?mura discovered a class of compounds, called avermectins, that kill parasitic roundworms that cause infections such as river blindness and lymphatic filariasis. The most potent of these was released onto the market in 1981 as the drug ivermectin.

Tu, who won a Lasker prize in 2011, developed the antimalarial drug artemisinin in the late 1960s and 1970s. She is the first China-based scientist to win a science Nobel.

Malaria breakthrough

In the 1960s, the main treatments for malaria were chloroquine and quinine, but they were proving increasingly ineffective. So in 1967, China established a national project against malaria to discover new therapies.

Working at the China Academy of Chinese Medical Sciences, Tu and her team screened more than 2,000 Chinese herbal remedies to search for drugs with antimalarial activity. An extract from the wormwood plant Artemisia annua proved especially effective and by 1972, the researchers had isolated chemically pure artemisinin.

That Tu won the Nobel prize is "great news", says Yi Rao, a neuroscientist at Peking University in Beijing who has researched the discovery of artemisinin. "I’m very happy about this. She totally deserves it.”

But there has been some controversy over credit for the discovery, Rao points out, so Tu has never won a major award in China. She has not been elected to either of China's major academies — neither the Chinese Academy of Sciences nor the Chinese Academy of Engineering.

“Though other people were involved, Tu was clearly the undisputed leader,” says Rao. “But she’s never been given fair recognition within China.”

Roundworm discovery

Working in Japan, ?mura isolated strains of a group of soil bacteria called Streptomyces that were known to have antimicrobial properties. In 1974, he pulled out a promising organism from soil near a golf course, and sent it, along with others, to a team led by Campbell at the Merck Institute for Therapeutic Research in Rahway, New Jersey. (?mura’s institute had signed a research partnership with Merck in 1973).

Campbell’s team isolated avermectins from the bacterial cultures and tweaked the structure of one of the most promising compounds to develop it into a drug — ivermectin. In 1987, Merck announced that it would donate the drug to anyone who needed it for treatment of onchocerciasis (also known as river blindness). A decade later, the firm began giving away the drug to treat lymphatic filariasis. Each year, Merck gives away some 270 million treatments of the drug, according to the Mectizan Donation Program, in Decatur, Georgia.

This year's prize highlights the global acceptance of the importance of parasitic infections, and neglected tropical diseases in general, says Stephen Ward at the Liverpool School of Tropical Medicine, UK. He notes that artemisinin has "saved possibly millions of lives" — although resistance to the drug is on the rise in parts of southeast Asia — and that ivermectin has protected millions from disease.

“It may refocus us on the idea that the immense diversity of products out there in the natural world is a great starting point for drug discovery,” he says.