Vaccines and Broadly Neutralizing Antibodies for HIV-1 Prevention

Despite decades of research and the success of antiretroviral therapy (ART) for treatment and preexposure prophylaxis (PrEP), the global HIV-1 pandemic persists. Current prevention methods face significant hurdles, including issues with patient access, long-term compliance, and potential drug toxicity. Consequently, there is a critical need for immunologic interventions, specifically active immunization via vaccines and passive immunization using broadly neutralizing antibodies (bNAbs).

The authors evaluate two primary immunologic approaches. First, vaccine development aims to elicit either nonneutralizing antibodies (nNAbs) that mediate protective functions like antibody-dependent cellular cytotoxicity (ADCC) or potent T cell responses. Second, passive immunization involves the direct administration of bNAbs. While bNAbs have demonstrated exceptional potency and breadth in laboratory settings, their clinical application is complicated by the virus's rapid evolution and profound sequence diversity, particularly in the envelope glycoprotein (Env).

HIV-1's extreme variability, driven by high replication rates and immune selection pressure, creates a moving target for any immune-based intervention. The authors highlight that within-host viral diversity—where a single infected individual harbors a swarm of variants—can lead to the rapid selection of resistant strains. This necessitates the use of combination therapies, such as cocktails of three or more bNAbs, to ensure that at least two antibodies remain active against the majority of circulating viral variants. The paper argues that defining the specific neutralization titers required for protection is essential for guiding the design of next-generation vaccines and optimizing passive immunization protocols.