Abstract

Vaccine design is challenging when the infectious agent is genetically diverse. Polyvalent 'mosaic' antigens might be used to address this challenge, and these two studies show promising results in monkeys infected with HIV-1 ( pages 268–270 and 324–328 ). The worldwide diversity of HIV-1 presents an unprecedented challenge for vaccine development1,2. Antigens derived from natural HIV-1 sequences have elicited only a limited breadth of cellular immune responses in nonhuman primate studies and clinical trials to date. Polyvalent 'mosaic' antigens, in contrast, are designed to optimize cellular immunologic coverage of global HIV-1 sequence diversity3. Here we show that mosaic HIV-1 Gag, Pol and Env antigens expressed by recombinant, replication-incompetent adenovirus serotype 26 vectors markedly augmented both the breadth and depth without compromising the magnitude of antigen-specific T lymphocyte responses as compared with consensus or natural sequence HIV-1 antigens in rhesus monkeys. Polyvalent mosaic antigens therefore represent a promising strategy to expand cellular immunologic vaccine coverage for genetically diverse pathogens such as HIV-1.