Searching for a Parasite's Weak Spot

摘要

"Optimism" is not a word usually associated with the pursuit of a malaria vaccine. "Frustration" is more appropriate. Over the years, researchers confronting the extraordinarily complex parasite have suffered a string of disappointments interspersed with some high-profile setbacks, as promising candidate vaccines have failed to perform up to expectations. The scientific obstacles are enormous: Compared to a virus, with its dozen or so genes and relatively monomani-acal approach to evading the human immune system, the malaria parasite has 14 chromosomes, perhaps 7000 genes, and a four-stage life cycle as it passes from humans to mosquitoes and back again. It is almost demonically efficient at evading the human immune response. Yet, something akin to legitimate optimism has been creeping into the field.