The 2009 TIME 100

To many, the name Seth Berkley is synonymous with IAVI — the International AIDS Vaccine Initiative, which he founded and has run for more than a decade. But only those who know him well appreciate the full breadth of his experience and deep tenacity of his character. From trekking remote parts of Tibet and Namibia to piloting airplanes and sailing boats, there are few topics with which Berkley is not personally familiar.

But since early in his career, Berkley, 52, has dedicated himself to fighting suffering around the world. At the Centers for Disease Control and Prevention, his work focused on special pathogens, including developing novel interventions for a disease called Brazilian purpuric fever that was killing children in Brazil. While on loan to the Department of State, he traveled by camel through rebel-controlled territory in Darfur, in western Sudan, and documented the worst famine ever scientifically evaluated in history.

However, the work that Berkley is known for now, at IAVI, is his most important contribution. While it is impossible to predict health technology and the social and economic factors that may affect the spread of HIV, it is clear that IAVI holds much potential to eradicate a great source of death and misery around the world. I am grateful to see someone so talented and committed at the helm of this important effort.

Brin is co-founder and president of Google