Asked how seriously he takes the danger to the western world of Ebola virus looming out of Africa, molecular biologist Gary Nabel, director of the NIH Vaccine Research Center (VRC), in Bethesda, Md., commented: "None of us has a crystal ball. What I do know is that we know how explosive a virus Ebola is. It can replicate very rapidly. And we know that people can walk around with this infection for seven days without even knowing it - and not being diagnosed for even longer periods of time - before they die." He pointed out, "it takes about 12 hours to fly over from Africa to the U.S. So it's not inconceivable that it could arrive here."

An editorial titled "Fighting the Ebola virus," accompanying Nabel's paper in Nature, made the point that "Some have rightly raised concerns about the amount of effort spent studying Ebola, given that it affects relatively few people compared with the major pathogens in Africa, such as HIV and malaria."

To which Nabel responded, "I do think we should put money into AIDS and TB and malaria. But the lessons that we've learned from Ebola are basic, and can even apply to those other viruses and infections. In fact, we're using some of these approaches for AIDS vaccine development."

He made a second point: "Viruses are moving targets. If this were 1975 and you were studying a little-known virus in Africa called HIV that appeared sporadically in monkeys, you might have raised the very same question. So it gets back to the issue - true in virology and throughout medicine - if you're going to intervene, you must do it as early as you possibly can.

"Vaccines are really the ultimate embodiment of that principle. In fact, vaccines have been the most cost-effective form of medical treatment that we have," Nabel said. "Think about the 200 years of smallpox vaccine, and how that has completely changed the face of the planet. So for me, there's tremendous leverage in our vaccine investment, in preventing future diseases, as well as applying them to a variety of different viruses and illnesses."

- David N. Leff