Mutation at a Single Position in the V2 Domain of the HIV-1 Envelope Protein Confers Neutralization Sensitivity to a Highly Neutralization-Resistant Virus

Department of Biomolecular Engineering, Baskin School of Engineering, University of California, Santa Cruz, 1156 High Street, MS-SOE2, Santa Cruz, CA 95064, USA.
Journal of Virology (Impact Factor: 4.44). 11/2010; 84(21):11200-9. DOI: 10.1128/JVI.00790-10
Source: PubMed


Understanding the determinants of neutralization sensitivity and resistance is important for the development of an effective human immunodeficiency virus type 1 (HIV-1) vaccine. In these studies, we have made use of the swarm of closely related envelope protein variants (quasispecies) from an extremely neutralization-resistant clinical isolate in order to identify mutations that conferred neutralization sensitivity to antibodies in sera from HIV-1-infected individuals. Here, we describe a virus with a rare mutation at position 179 in the V2 domain of gp120, where replacement of aspartic acid (D) by asparagine (N) converts a virus that is highly resistant to neutralization by multiple polyclonal and monoclonal antibodies, as well as antiviral entry inhibitors, to one that is sensitive to neutralization. Although the V2 domain sequence is highly variable, D at position 179 is highly conserved in HIV-1 and simian immunodeficiency virus (SIV) and is located within the LDI/V recognition motif of the recently described α4β7 receptor binding site. Our results suggest that the D179N mutation induces a conformational change that exposes epitopes in both the gp120 and the gp41 portions of the envelope protein, such as the CD4 binding site and the MPER, that are normally concealed by conformational masking. Our results suggest that D179 plays a central role in maintaining the conformation and infectivity of HIV-1 as well as mediating binding to α4β7.

Download full-text


Available from: Sara M O'Rourke, Jan 30, 2015
9 Reads
  • Source
    • "To establish and validate our assay setups we analyzed a panel of four JR-FL env variants for their cell-cell transmission and free virus entry capacity. Besides JR-FL wildtype (wt) we probed the V2 point mutant JR-FL I165P (that has no impact on free virus infectivity and served as control) and V2 point mutations L175P [11] and D180N [61], which were previously described to interfere with env structural integrity and neutralization sensitivity. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background Variable loops 1 and 2 (V1V2) of the HIV-1 envelope glycoprotein gp120 perform two key functions: ensuring envelope trimer entry competence and shielding against neutralizing antibodies. While preserving entry functionality would suggest a high need for V1V2 sequence optimization and conservation, shielding efficacy is known to depend on a high flexibility of V1V2 giving rise to its substantial sequence variability. How entry competence of the trimer is maintained despite the continuous emergence of antibody escape mutations within V1V2 has not been resolved. Since HIV cell-cell transmission is considered a highly effective means of virus dissemination, we investigated whether cell-cell transmission may serve to enhance infectivity of V1V2 variants with debilitated free virus entry.ResultsIn a detailed comparison of wt and V1V2 mutant envelopes, V1V2 proved to be a key factor in ascertaining free virus infectivity, with V1V2 mutants displaying significantly reduced trimer integrity. Despite these defects, cell-cell transmission was able to partially rescue infectivity of V1V2 mutant viruses. We identified two regions, encompassing amino acids 156 to 160 (targeted by broadly neutralizing antibodies) and 175 to 180 (encompassing the ¿4ß7 binding site) which were particularly prone to free virus infectivity loss upon mutation but maintained infectivity in cell-cell transmission. Of note, V1V2 antibody shielding proved important during both free virus infection and cell-cell transmission.Conclusions Based on our data we propose a model for V1V2 evolution that centers on cell-cell transmission as a salvage pathway for virus replication. Escape from antibody neutralization may frequently result in V1V2 mutations that reduce free virus infectivity. Cell-cell transmission could provide these escape viruses with sufficiently high replication levels that enable selection of compensatory mutations, thereby restoring free virus infectivity while ensuring antibody escape. Thus, our study highlights the need to factor in cell-cell transmission when considering neutralization escape pathways of HIV-1.
    Retrovirology 09/2014; 11(1):75. DOI:10.1186/PREACCEPT-1148975491133162 · 4.19 Impact Factor
  • Source
    • "In conclusion, our results and those of others [21,22,56] demonstrate that escape from 2G12 can be achieved through different pathways in a subject-specific manner, previously shown for escape from autologous pressure [5,6] and other MAbs [58,59], and no obvious common signature motifs could be identified [60] thus suggesting that this complex epitope may be a difficult target for vaccines. A focus on shared neutralization epitopes that remain stable under immune pressure may lead to more effective vaccines. "
    [Show abstract] [Hide abstract]
    ABSTRACT: HIV-1 Envelope (Env) protein is the sole target of neutralizing antibodies (NAbs) that arise during infection to neutralize autologous variants. Under this immune pressure, HIV escape variants are continuously selected and over the course of infection Env becomes more neutralization resistant. Many common alterations are known to affect sensitivity to NAbs, including residues encoding potential N-linked glycosylation sites (PNGS). Knowledge of Env motifs associated with neutralization resistance is valuable for the design of an effective Env-based vaccine so we characterized Envs isolated longitudinally from a SHIVSF162P4 infected macaque for sensitivity to neutralizing monoclonal antibodies (MAbs) B12, 2G12, 4E10 and 2F5. The early Env, isolated from plasma at day 56 after infection, was the most sensitive and the late Env, from day 670, was the most resistant to MAbs. We identified four PNGS in these Envs that accumulated over time at positions 130, 139, 160 and 397. We determined that removal of these PNGS significantly increased neutralization sensitivity to 2G12, and conversely, we identified mutations by in silico analyses that contributed resistance to 2G12 neutralization. In order to expand our understanding of these PNGS, we analyzed Envs from clade B HIV-infected human subjects and identified additional glycan and amino acid changes that could affect neutralization by 2G12 in a context-dependent manner. Taken together, these in vitro and in silico analyses of clade B Envs revealed that 2G12 resistance is achieved by previously unrecognized PNGS substitutions in a context-dependent manner and by subject-specific pathways.
    PLoS ONE 09/2013; 8(9):e75277. DOI:10.1371/journal.pone.0075277 · 3.23 Impact Factor
  • Source
    • "Recent studies have shown that the central aspartic acid (D180) residue within the α4β7 recognition sequence (LDI/V) also appears to be an essential part of the conformational masking mechanism [37] used to shield neutralizing epitopes from neutralizing antibodies. Previous studies have referred to the V2 domain as the “global regulator of neutralization sensitivity” [18], [19] and have shown that the V2 domain interacts with other regions of gp120. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Recombinant gp120 (MN-rgp120) was a major component of the AIDSVAX B/E vaccine used in the RV144 trial. This was the first clinical trial to show that vaccination could prevent HIV infection in humans. A recent RV144 correlates of protection study found that protection correlated with the presence of antibodies to the V2 domain. It has been proposed that antibodies to the α4β7 binding site in the V2 domain might prevent HIV-1 infection by blocking the ability of virions to recognize α4β7 on activated T-cells. In this study we investigated the specificity of monoclonal antibodies (MAbs) to the V2 domain of MN-rgp120 and examined the possibility that these antibodies could inhibit the binding of MN-rgp120 to the α4β7 integrin. Nine MAbs to the V2 domain were isolated from mice immunized with recombinant envelope proteins. The ability of these MAbs to inhibit HIV infection, block the binding of gp120 to CD4, and block the binding of MN-rgp120 to the α4β7 integrin was measured. Mutational analysis showed that eight of the MAbs recognized two immunodominant clusters of amino acids (166-168 and 178-183) located at either end of the C strand within the four-strand anti-parallel sheet structure comprising the V1/V2 domain. These studies showed that the antigenic structure of the V2 domain is exceedingly complex and that MAbs isolated from mice immunized with MN-rgp120 exhibited a high level of strain specificity compared to MAbs to the V2 domain isolated from HIV-infected humans. We found that immunization with MN-rgp120 readily elicits antibodies to the V2 domain and some of these were able to block the binding of MN-rgp120 to the α4β7 integrin.
    PLoS ONE 06/2012; 7(6):e39045. DOI:10.1371/journal.pone.0039045 · 3.23 Impact Factor
Show more