Dataset Information

Autologous Antibody Responses to an HIV Envelope Glycan Hole Are Not Easily Broadened in Rabbits.

ABSTRACT: Extensive studies with subtype A BG505-derived HIV envelope glycoprotein (Env) immunogens have revealed that the dominant autologous neutralizing epitope in rabbits is located in an exposed region of the heavily glycosylated trimer that lacks potential N-linked glycosylation sites at positions 230, 241, and 289. The Env derived from B41, a subtype B virus, shares a glycan hole centered on positions 230 and 289. To test whether broader neutralization to the common glycan hole can be achieved, we immunized rabbits with B41 SOSIP (gp120-gp41 disulfide [SOS] with an isoleucine-to-proline mutation [IP] in gp41) alone, as well as B41 and BG505 coimmunization. We isolated autologous neutralizing antibodies (nAbs) and described their structure in complex with the B41 Env. Our data suggest that distinct autologous nAb lineages are induced by BG505 and B41 immunogens, even when both were administered together. In contrast to previously described BG505 glycan hole antibodies, the B41-specific nAbs accommodate the >97% conserved N241 glycan, which is present in B41. Single-particle cryo-electron microscopy studies confirmed that B41- and BG505-specific nAbs bind to overlapping glycan hole epitopes. We then used our high-resolution data to guide mutations in the BG505 glycan hole epitope in an attempt to broaden the reactivity of a B41-specific nAb, but we recovered only partial binding. Our data demonstrate that the lack of cross-reactivity in glycan hole antibodies is due to amino acid differences within the epitope, and our attempts to rationally design cross-reactive trimers resulted in only limited success. Thus, even for the immunodominant glycan hole shared between BG505 and B41, the prospect of designing prime-boost immunogens remains difficult.IMPORTANCE A glycan hole is one of the most dominant autologous neutralizing epitopes targeted on BG505 and B41 SOSIP trimer-immunized rabbits. Our high-resolution cryo-electron microscopy (cryoEM) studies of B41 in complex with a B41-specific antibody complex elucidate the molecular basis of this strain-specific glycan hole response. We conclude that even for the immunodominant glycan hole shared between BG505 and B41, the prospect of designing prime-boost immunogens remains difficult.

SUBMITTER: Yang YR

PROVIDER: S-EPMC7081899 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Autologous Antibody Responses to an HIV Envelope Glycan Hole Are Not Easily Broadened in Rabbits.

Yang Yuhe R YR McCoy Laura E LE van Gils Marit J MJ Andrabi Raiees R Turner Hannah L HL Yuan Meng M Cottrell Christopher A CA Ozorowski Gabriel G Voss James J Pauthner Matthias M Polveroni Thomas M TM Messmer Terrence T Wilson Ian A IA Sanders Rogier W RW Burton Dennis R DR Ward Andrew B AB

Journal of virology 20200317 7

Extensive studies with subtype A BG505-derived HIV envelope glycoprotein (Env) immunogens have revealed that the dominant autologous neutralizing epitope in rabbits is located in an exposed region of the heavily glycosylated trimer that lacks potential N-linked glycosylation sites at positions 230, 241, and 289. The Env derived from B41, a subtype B virus, shares a glycan hole centered on positions 230 and 289. To test whether broader neutralization to the common glycan hole can be achieved, we ...[more]

PMID: 31941772

Similar Datasets

Project description:The human immunodeficiency virus type 1 (HIV-1) trimeric envelope glycoprotein (Env) is heavily glycosylated, creating a dense glycan shield that protects the underlying peptidic surface from antibody recognition. The absence of conserved glycans, due to missing potential N-linked glycosylation sites (PNGS), can result in strain-specific, autologous neutralizing antibody (NAb) responses. Here, we sought to gain a deeper understanding of the autologous neutralization by introducing holes in the otherwise dense glycan shields of the AMC011 and AMC016 SOSIP trimers. Specifically, when we knocked out the N130 and N289 glycans, which are absent from the well-characterized B41 SOSIP trimer, we observed stronger autologous NAb responses. We also analyzed the highly variable NAb responses induced in rabbits by diverse SOSIP trimers from subtypes A, B, and C. Statistical analysis, using linear regression, revealed that the cumulative area exposed on a trimer by glycan holes correlates with the magnitude of the autologous NAb response. IMPORTANCE Forty years after the first description of HIV-1, the search for a protective vaccine is still ongoing. The sole target for antibodies that can neutralize the virus are the trimeric envelope glycoproteins (Envs) located on the viral surface. The glycoprotein surface is covered with glycans that shield off the underlying protein components from recognition by the immune system. However, the Env trimers of some viral strains have holes in the glycan shield. Immunized animals developed antibodies against such glycan holes. These antibodies are generally strain specific. Here, we sought to gain a deeper understanding of what drives these specific immune responses. First, we show that strain-specific neutralizing antibody responses can be increased by creating artificial holes in the glycan shield. Second, when studying a diverse set of Env trimers with different characteristics, we found that the surface area of the glycan holes contributes prominently to the induction of strain-specific neutralizing antibodies.

Project description:We recently reported induction of broadly neutralizing antibodies (bnAbs) against multiple HIV-1 (human immunodeficiency virus type 1) isolates in rabbits, albeit weak against tier 2 viruses, using a monomeric gp120 derived from an M group consensus sequence (MCON6). To better understand the nature of the neutralizing activity, detailed characterization of immunological properties of the protein was performed. Immunogenic linear epitopes were identified during the course of immunization, and spatial distribution of these epitopes was determined. Subdomain antibody target analyses were done using the gp120 outer domain (gp120-OD) and eOD-GT6, a protein based on a heterologous sequence. In addition, refined epitope mapping analyses were done by competition assays using several nAbs with known epitopes.Based on linear epitope mapping analyses, the V3 loop was most immunogenic, followed by C1 and C5 regions. The V1/V2 loop was surprisingly non-immunogenic. Many immunogenic epitopes were clustered together even when they were distantly separated in primary sequence, suggesting the presence of immunogenic hotspots on the protein surface. Although substantial antibody responses were directed against the outer domain, only about 0.1% of the antibodies bound eOD-GT6. Albeit weak, antibodies against peptides that corresponded to a part of the bnAb VRC01 binding site were detected. Although gp120-induced antibodies could not block VRC01 binding to eOD-GT6, they were able to inhibit VRC01 binding to both gp120 and trimeric BG505 SOSIP gp140. The immune sera also efficiently competed with CD4-IgG2, as well as nAbs 447-52D, PGT121 and PGT126, in binding to gp120.The results suggest that some antibodies that bind at or near known bnAb epitopes could be partly responsible for the breadth of neutralizing activity induced by gp120 in our study. Immunization strategies that enhance induction of these antibodies relative to others (e.g. V3 loop), and increase their affinity, could improve protective efficacy of an HIV-1 vaccine.

Dataset Information

Autologous Antibody Responses to an HIV Envelope Glycan Hole Are Not Easily Broadened in Rabbits.

Publications

Autologous Antibody Responses to an HIV Envelope Glycan Hole Are Not Easily Broadened in Rabbits.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets