9oed | pdb_00009oed
Ab1999 in complex with HIV-1 Env RC1
Structural highlights
FunctionQ2N0S6_HV1 Envelope glycoprotein gp160: Oligomerizes in the host endoplasmic reticulum into predominantly trimers. In a second time, gp160 transits in the host Golgi, where glycosylation is completed. The precursor is then proteolytically cleaved in the trans-Golgi and thereby activated by cellular furin or furin-like proteases to produce gp120 and gp41.[HAMAP-Rule:MF_04083] Surface protein gp120: Attaches the virus to the host lymphoid cell by binding to the primary receptor CD4. This interaction induces a structural rearrangement creating a high affinity binding site for a chemokine coreceptor like CXCR4 and/or CCR5. Acts as a ligand for CD209/DC-SIGN and CLEC4M/DC-SIGNR, which are respectively found on dendritic cells (DCs), and on endothelial cells of liver sinusoids and lymph node sinuses. These interactions allow capture of viral particles at mucosal surfaces by these cells and subsequent transmission to permissive cells. HIV subverts the migration properties of dendritic cells to gain access to CD4+ T-cells in lymph nodes. Virus transmission to permissive T-cells occurs either in trans (without DCs infection, through viral capture and transmission), or in cis (following DCs productive infection, through the usual CD4-gp120 interaction), thereby inducing a robust infection. In trans infection, bound virions remain infectious over days and it is proposed that they are not degraded, but protected in non-lysosomal acidic organelles within the DCs close to the cell membrane thus contributing to the viral infectious potential during DCs' migration from the periphery to the lymphoid tissues. On arrival at lymphoid tissues, intact virions recycle back to DCs' cell surface allowing virus transmission to CD4+ T-cells.[HAMAP-Rule:MF_04083] Transmembrane protein gp41: Acts as a class I viral fusion protein. Under the current model, the protein has at least 3 conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During fusion of viral and target intracellular membranes, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes. Complete fusion occurs in host cell endosomes and is dynamin-dependent, however some lipid transfer might occur at the plasma membrane. The virus undergoes clathrin-dependent internalization long before endosomal fusion, thus minimizing the surface exposure of conserved viral epitopes during fusion and reducing the efficacy of inhibitors targeting these epitopes. Membranes fusion leads to delivery of the nucleocapsid into the cytoplasm.[HAMAP-Rule:MF_04083] Publication Abstract from PubMedSequential immunization is a promising approach to elicit broadly neutralizing antibodies (bNAbs) against the HIV-1 Envelope (Env). However, available protocols are inefficient and involve multiple immunizations over long periods of time. Here, we present WIN332, a new engineered Env immunogen that induces a new class of Asn332-glycan-independent antibodies to the conserved V3-glycan epitope of Env with low inhibitory activity indicative of a neutralization activity after a single bolus immunization in nonhuman primates. WIN332 binds to precursors of canonical human Asn332-glycan-dependent (type-I) V3-glycan bNAbs but also of a first-of-its-class Asn332-glycan-independent (type-II) V3-glycan bNAb. A single immunization elicits low inhibitory serum and monoclonal antibodies that are boosted and affinity matured with a heterologous immunogen. Electron microscopy polyclonal epitope mapping analysis of serum antibodies, antibody cloning and cryogenic electron microscopy analysis reveals that WIN332 elicits Asn332-glycan-independent antibodies with striking sequence and binding similarities with the most potent human type-I and type-II V3-glycan bNAbs. Thus, WIN332 is a promising vaccine candidate to streamline V3-glycan bNAb elicitation. Rapid elicitation of neutralizing Asn332-glycan-independent antibodies to the V3-glycan epitope of HIV-1 Env in nonhuman primates.,Relano-Rodriguez I, Du J, Lin ZJ, Kerwin M, Tarquis-Medina M, Urbano E, Cui J, Watkins M, Lavine CL, Zhao P, Habib R, Agostino C, Ghosh S, Park J, Boroughs C, Walsh AA, Melo MB, Shukla N, Shaw GM, Hahn BH, Irvine DJ, Wells L, Weiner DB, Seaman MS, Kulp DW, Veazey RS, Pallesen J, Escolano A Nat Immunol. 2026 Feb 3. doi: 10.1038/s41590-025-02408-z. PMID:41634485[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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