Study could aid development of more effective vaccines. For the first time, scientists have tracked in a patient the evolution of a potent immune molecule that recognizes many different HIV viruses. By revealing how these molecules — called broadly neutralizing antibodies — develop, the research could inform efforts to make vaccines that elicit similar antibodies that can protect people from becoming infected with HIV. The researchers, led by Barton Haynes of Duke University School of Medicine in Durham, North Carolina, found that broadly neutralizing antibodies developed only after the population of viruses in the patient had diversified — something that...