Naïve B-cell receptor recognizing HIV-1 envelope glycoprotein (Naïve HIV-1 Env BCR)

Naïve B-cell receptors (BCRs) recognizing the HIV-1 envelope (Env) glycoprotein are the primary targets for germline-targeting vaccine strategies designed to elicit broadly neutralizing antibodies (bnAbs). These receptors are expressed on the surface of B cells that have not yet encountered their cognate antigen but possess the specific genetic architecture, such as particular heavy-chain variable (VH) gene segments, required to bind conserved but recessed epitopes on the HIV-1 Env (Jardine et al., Science, 2013). Because the native HIV-1 Env is highly shielded by glycans and exhibits extreme sequence variability, standard immunogens typically fail to activate these rare naïve B cells. Engineered immunogens, such as the eOD-GT8 60mer, are specifically designed to overcome this barrier by binding to these germline BCRs with sufficient affinity to initiate an immune response (Leggat et al., Science, 2022). The therapeutic goal of targeting these receptors is to guide the B cells through a directed process of affinity maturation, eventually resulting in mature bnAbs capable of neutralizing a wide range of HIV-1 variants (Schief et al., Science, 2015). This approach represents a paradigm shift in vaccinology, moving from empirical testing to the rational design of agents that hit specific molecular targets within the immune repertoire.

Other names

Germline HIV-1 Env-binding BCRPrecursor B-cell receptor for HIV-1 broadly neutralizing antibodiesHIV-1 Env-specific naïve BCRbnAb precursor BCR

Germline-targeting immunogens act as molecular templates that bind with high affinity to rare naïve B-cell receptors (BCRs) possessing specific genetic motifs (e.g., VRC01-class precursors). This binding event triggers B-cell receptor signaling, leading to the activation, clonal expansion, and recruitment of these specific B cells into germinal centers, where they undergo iterative rounds of somatic hypermutation to eventually produce broadly neutralizing antibodies (bnAbs).