9be9 | pdb_00009be9
HIV-1 Env 16055 dGly4 NFL
Structural highlights
FunctionA1EAI1_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 PubMedEvaluation of recombinant HIV-1 surface glycoproteins (Env) as vaccine candidates for Phase I human experimental trials often requires production of cGMP-grade well-ordered Env trimers. Here, we report an accelerated cGMP compatible approach for expression and purification of a stabilized HIV clade C-derived trimer '16055 DG4 NFL' (for native flexibly linked). This recombinant trimer was expressed from CHO-S cells using a MaxCyte(R) VLX electroporation-based transient transfection process. The 16055 DG4 NFL was designed with multiple internal stabilizing mutations and, as well, deletion of four N-linked glycans (DG4) proximal to the CD4 binding site (CD4bs) engineered to improve B cell recognition of this conserved neutralizing determinant. The transient process circumvents the need to develop stable cell lines expressing the Env trimers that is often the most time-consuming step impacting vaccine development timelines. The 16055 DG4 NFL trimer was purified by immunoaffinity chromatography using the broadly neutralizing antibody (bNAb), PGT145. Following additional downstream processing steps, purified trimer was vialed, frozen and stored at -80 degrees C. Upon thaw and analysis, the trimer displayed homogeneity and a near-native conformation as determined by size-exclusion chromatography (SEC), negative stain and cryo-electron microscopy (EM), differential scanning calorimetry (DSC) and biolayer interferometry (BLI). The immunogenicity of the trimer was tested in rabbits with bolus, escalating dose and divided dose immunization regimens. Rabbits from all three regimens elicited tier 2 autologous neutralizing antibodies that targeted the exposed protein region at the CD4bs. The trimer is currently under investigation in a human clinical trial (NCT06332339) for safety, tolerability and as a priming candidate followed by heterologous boosting to potentially elicit cross-neutralizing antibodies. Accelerated cGMP production of near-native HIV-1 Env trimers following electroporation transfection and immunogenicity analysis.,Bale S, Gustchina E, Guenaga J, Ayala V, Lee WH, Ozorowski G, Whitney S, Wilson R, Baboo S, Diedrich JK, Doyle ED, Hudacik L, Ben-Akiva E, Rodrigues KA, Irvine DJ, Yates JR 3rd, Paulson JC, Ward AB, Fouts T, Wyatt RT NPJ Vaccines. 2025 Aug 20;10(1):198. doi: 10.1038/s41541-025-01218-6. PMID:40835829[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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