Researchers have reached an important milestone in the effort to harness the power of so-called broadly neutralizing antibodies against HIV for use as treatment and prevention of the virus. Experiments in monkeys found that synthesizing three such antibodies into a single antibody that targets three different sites on the surface of the virus more effectively protected the primates against exposure to SHIV, a simian version of HIV, than the individual antibodies. This finding suggests that, just as with standard antiretroviral treatment, a combination-therapy approach will prove the most potent and raise the highest barrier against resistant virus. The French pharma company Sanofi and the U.S. National Institute for Allergies and Infectious Diseases are gearing up for a Phase I human trial of the trispecific antibody to begin this year. An approved antibody would ideally be given as an intermittent infusion.