Progress toward active or passive HIV-1 vaccination.

AIDS is a preventable disease. Nevertheless, according to UNAIDS, 2.1 million individuals were infected with HIV-1 in 2015 worldwide. An effective vaccine is highly desirable. Most vaccines in clinical use today prevent infection because they elicit antibodies that block pathogen entry. Consistent with this general rule, studies in experimental animals have shown that broadly neutralizing antibodies to HIV-1 can prevent infection, suggesting that a vaccine that elicits such antibodies would be protective. However, despite significant efforts over the last 30 years, attempts to elicit broadly HIV-1 neutralizing antibodies by vaccination failed until recent experiments in genetically engineered mice were finally successful. Here, we review the key breakthroughs and remaining obstacles to the development of active and passive HIV-1 vaccines.