RESUMO
The HIV-1 envelope (Env) spike contains limited epitopes for broadly neutralizing antibodies (bNAbs); thus, most neutralizing antibodies are strain specific. The 8ANC195 epitope, defined by crystal and electron microscopy (EM) structures of bNAb 8ANC195 complexed with monomeric gp120 and trimeric Env, respectively, spans the gp120 and gp41 Env subunits. To investigate 8ANC195's gp41 epitope at higher resolution, we solved a 3.58 Å crystal structure of 8ANC195 complexed with fully glycosylated Env trimer, revealing 8ANC195 insertion into a glycan shield gap to contact gp120 and gp41 glycans and protein residues. To determine whether 8ANC195 recognizes the CD4-bound open Env conformation that leads to co-receptor binding and fusion, one of several known conformations of virion-associated Env, we solved EM structures of an Env/CD4/CD4-induced antibody/8ANC195 complex. 8ANC195 binding partially closed the CD4-bound trimer, confirming structural plasticity of Env by revealing a previously unseen conformation. 8ANC195's ability to bind different Env conformations suggests advantages for potential therapeutic applications.
Assuntos
Anticorpos Neutralizantes/metabolismo , Proteína gp120 do Envelope de HIV/química , Proteína gp120 do Envelope de HIV/metabolismo , HIV-1/química , Anticorpos Neutralizantes/ultraestrutura , Epitopos , Proteína gp120 do Envelope de HIV/ultraestrutura , Humanos , Imunoglobulina G/química , Imunoglobulina G/metabolismo , Microscopia Eletrônica de Transmissão , Modelos Moleculares , Conformação Proteica , Difração de Raios XRESUMO
A subset of individuals infected with HIV-1 develops broadly neutralizing antibodies (bNAbs) that can prevent infection, but it has not yet been possible to elicit these antibodies by immunization. To systematically explore how immunization might be tailored to produce them, we generated mice expressing the predicted germline or mature heavy chains of a potent bNAb to the CD4 binding site (CD4bs) on the HIV-1 envelope glycoprotein (Env). Immunogens specifically designed to activate B cells bearing germline antibodies are required to initiate immune responses, but they do not elicit bNAbs. In contrast, native-like Env trimers fail to activate B cells expressing germline antibodies but elicit bNAbs by selecting for a restricted group of light chains bearing specific somatic mutations that enhance neutralizing activity. The data suggest that vaccination to elicit anti-HIV-1 antibodies will require immunization with a succession of related immunogens.
Assuntos
Anticorpos Neutralizantes/genética , Anticorpos Antivirais/genética , Técnicas de Introdução de Genes , HIV-1/imunologia , Cadeias Pesadas de Imunoglobulinas/genética , Animais , Antígenos Virais , Linfócitos B/imunologia , Antígenos CD4/metabolismo , Infecções por HIV/imunologia , Humanos , Camundongos , Mutação , Baço/citologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/metabolismoRESUMO
Despite 30 years of effort, there is no effective vaccine for HIV-1. However, antibodies can prevent HIV-1 infection in humanized mice and macaques when passively transferred. New single-cell-based methods have uncovered many broad and potent donor-derived antibodies, and structural studies have revealed the molecular bases for their activities. The new data suggest why such antibodies are difficult to elicit and inform HIV-1 vaccine development efforts. In addition to protecting against infection, the newly identified antibodies can suppress active infections in mice and macaques, suggesting they could be valuable additions to anti-HIV-1 therapies and to strategies to eradicate HIV-1 infection.
Assuntos
Vacinas contra a AIDS/imunologia , Anticorpos Anti-HIV/imunologia , Infecções por HIV/imunologia , Infecções por HIV/prevenção & controle , HIV-1 , Vacinas contra a AIDS/uso terapêutico , Animais , Anticorpos Neutralizantes/química , Anticorpos Neutralizantes/imunologia , Anticorpos Anti-HIV/química , Humanos , Imunoterapia , Produtos do Gene env do Vírus da Imunodeficiência Humana/química , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologiaRESUMO
The nature of the antigens recognized by γδ T cells and their potential recognition of major histocompatibility complex (MHC)-like molecules has remained unclear. Members of the CD1 family of lipid-presenting molecules are suggested ligands for Vδ1 TCR-expressing γδ T cells, the major γδ lymphocyte population in epithelial tissues. We crystallized a Vδ1 TCR in complex with CD1d and the self-lipid sulfatide, revealing the unusual recognition of CD1d by germline Vδ1 residues spanning all complementarity-determining region (CDR) loops, as well as sulfatide recognition separately encoded by nongermline CDR3δ residues. Binding and functional analysis showed that CD1d presenting self-lipids, including sulfatide, was widely recognized by gut Vδ1+ γδ T cells. These findings provide structural demonstration of MHC-like recognition of a self-lipid by γδ T cells and reveal the prevalence of lipid recognition by innate-like T cell populations.
Assuntos
Antígenos CD1d/química , Lipídeos/imunologia , Modelos Moleculares , Receptores de Antígenos de Linfócitos T gama-delta/química , Receptores de Antígenos de Linfócitos T gama-delta/metabolismo , Linfócitos T/metabolismo , Animais , Apresentação de Antígeno , Antígenos CD1d/metabolismo , Cristalografia por Raios X , Epitopos , Humanos , Células Jurkat , Complexo Principal de Histocompatibilidade/imunologia , Estrutura Quaternária de Proteína , Sulfoglicoesfingolipídeos/química , Sulfoglicoesfingolipídeos/metabolismoRESUMO
CD1 molecules function to present lipid-based antigens to T cells. Here we present the crystal structure of CD1c at 2.5 Å resolution, in complex with the pathogenic Mycobacterium tuberculosis antigen mannosyl-ß1-phosphomycoketide (MPM). CD1c accommodated MPM's methylated alkyl chain exclusively in the A' pocket, aided by a unique exit portal underneath the α1 helix. Most striking was an open F' pocket architecture lacking the closed cavity structure of other CD1 molecules, reminiscent of peptide binding grooves of classical major histocompatibility complex molecules. This feature, combined with tryptophan-fluorescence quenching during loading of a dodecameric lipopeptide antigen, provides a compelling model by which both the lipid and peptide moieties of the lipopeptide are involved in CD1c presentation of lipopeptides.
Assuntos
Antígenos de Bactérias/química , Antígenos CD1/química , Glicoproteínas/química , Modelos Imunológicos , Mycobacterium tuberculosis/imunologia , Conformação Proteica , Apresentação de Antígeno , Variação Antigênica , Antígenos de Bactérias/imunologia , Antígenos CD1/imunologia , Clonagem Molecular , Biologia Computacional , Cristalização , Glicoproteínas/imunologia , Antígenos de Histocompatibilidade/metabolismo , Humanos , Fragmentos de Peptídeos/metabolismo , Ligação Proteica , Raios XRESUMO
Previous studies have shown that sera from HIV-1-infected individuals contain antibodies able to mediate antibody-dependent cellular cytotoxicity (ADCC). These antibodies preferentially recognize envelope glycoprotein (Env) epitopes induced upon CD4 binding. Here, we show that a highly conserved tryptophan at position 69 of the gp120 inner domain is important for ADCC mediated by anti-cluster A antibodies and sera from HIV-1-infected individuals.
Assuntos
Citotoxicidade Celular Dependente de Anticorpos , Anticorpos Anti-HIV/imunologia , Proteína gp120 do Envelope de HIV/imunologia , HIV-1/imunologia , Sequência Conservada , HumanosRESUMO
The CD4 binding site (CD4bs) on the envelope glycoprotein is a major site of vulnerability that is conserved among different HIV-1 isolates. Many broadly neutralizing antibodies (bNAbs) to the CD4bs belong to the VRC01 class, sharing highly restricted origins, recognition mechanisms and viral escape pathways. We sought to isolate new anti-CD4bs bNAbs with different origins and mechanisms of action. Using a gp120 2CC core as bait, we isolated antibodies encoded by IGVH3-21 and IGVL3-1 genes with long CDRH3s that depend on the presence of the N-linked glycan at position-276 for activity. This binding mode is similar to the previously identified antibody HJ16, however the new antibodies identified herein are more potent and broad. The most potent variant, 179NC75, had a geometric mean IC80 value of 0.42 µg/ml against 120 Tier-2 HIV-1 pseudoviruses in the TZM.bl assay. Although this group of CD4bs glycan-dependent antibodies can be broadly and potently neutralizing in vitro, their in vivo activity has not been tested to date. Here, we report that 179NC75 is highly active when administered to HIV-1-infected humanized mice, where it selects for escape variants that lack a glycan site at position-276. The same glycan was absent from the virus isolated from the 179NC75 donor, implying that the antibody also exerts selection pressure in humans.
Assuntos
Anticorpos Neutralizantes/imunologia , Antígenos CD4/imunologia , Anticorpos Anti-HIV/imunologia , HIV-1/imunologia , Polissacarídeos/química , Animais , Sítios de Ligação , Células HEK293 , Anticorpos Anti-HIV/química , Humanos , CamundongosRESUMO
Advances in single-cell antibody cloning methods have led to the identification of a variety of broadly neutralizing anti-HIV-1 antibodies. We developed a computational tool (Antibody Database) to help identify critical residues on the HIV-1 envelope protein whose natural variation affects antibody activity. Our simplifying assumption was that, for a given antibody, a significant portion of the dispersion of neutralization activity across a panel of HIV-1 strains is due to the amino acid identity or glycosylation state at a small number of specific sites, each acting independently. A model of an antibody's neutralization IC50 was developed in which each site contributes a term to the logarithm of the modeled IC50. The analysis program attempts to determine the set of rules that minimizes the sum of the residuals between observed and modeled IC50 values. The predictive quality of the identified rules may be assessed in part by whether there is support for rules within individual viral clades. As a test case, we analyzed antibody 8ANC195, an anti-glycoprotein gp120 antibody of unknown specificity. The model for this antibody indicated that several glycosylation sites were critical for neutralization. We evaluated this prediction by measuring neutralization potencies of 8ANC195 against HIV-1 in vitro and in an antibody therapy experiment in humanized mice. These experiments confirmed that 8ANC195 represents a distinct class of glycan-dependent anti-HIV-1 antibody and validated the utility of computational analysis of neutralization panel data.
Assuntos
Anticorpos Neutralizantes/metabolismo , Epitopos/fisiologia , Anticorpos Anti-HIV/imunologia , Antígenos HIV/imunologia , HIV-1/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Sequência de Aminoácidos , Animais , Biologia Computacional/métodos , Mapeamento de Epitopos/métodos , Epitopos/química , Epitopos/genética , Antígenos HIV/química , Antígenos HIV/genética , Proteína gp120 do Envelope de HIV/química , Proteína gp120 do Envelope de HIV/genética , Proteína gp120 do Envelope de HIV/imunologia , HIV-1/genética , Humanos , Camundongos , Camundongos Endogâmicos NOD , Camundongos Knockout , Modelos Imunológicos , Modelos Moleculares , Dados de Sequência Molecular , Testes de Neutralização , Produtos do Gene env do Vírus da Imunodeficiência Humana/química , Produtos do Gene env do Vírus da Imunodeficiência Humana/genéticaRESUMO
Efforts to design an effective antibody-based vaccine against HIV-1 would benefit from understanding how germ-line B-cell receptors (BCRs) recognize the HIV-1 gp120/gp41 envelope spike. Potent VRC01-like (PVL) HIV-1 antibodies derived from the VH1-2*02 germ-line allele target the conserved CD4 binding site on gp120. A bottleneck for design of immunogens capable of eliciting PVL antibodies is that VH1-2*02 germ-line BCR interactions with gp120 are uncharacterized. Here, we report the structure of a VH1-2*02 germ-line antibody alone and a germ-line heavy-chain/mature light-chain chimeric antibody complexed with HIV-1 gp120. VH1-2*02 residues make extensive contacts with the gp120 outer domain, including all PVL signature and CD4 mimicry interactions, but not critical CDRH3 contacts with the gp120 inner domain and bridging sheet that are responsible for the improved potency of NIH45-46 over closely related clonal variants, such as VRC01. Our results provide insight into initial recognition of HIV-1 by VH1-2*02 germ-line BCRs and may facilitate the design of immunogens tailored to engage and stimulate broad and potent CD4 binding site antibodies.
Assuntos
Anticorpos Neutralizantes/química , Anticorpos Anti-HIV/química , Proteína gp120 do Envelope de HIV/química , Receptores de Antígenos de Linfócitos B/química , Alelos , Sequência de Aminoácidos , Anticorpos Neutralizantes/imunologia , Sítios de Ligação , Sítios de Ligação de Anticorpos/imunologia , Linfócitos T CD4-Positivos/citologia , Linhagem Celular Tumoral , Cristalografia por Raios X , Anticorpos Anti-HIV/imunologia , HIV-1 , Humanos , Fragmentos de Imunoglobulinas/química , Fragmentos de Imunoglobulinas/imunologia , Imunoglobulina G/química , Imunoglobulina G/imunologia , Dados de Sequência Molecular , Mutação , Estrutura Terciária de Proteína , Homologia de Sequência de Aminoácidos , Ressonância de Plasmônio de SuperfícieRESUMO
Broadly neutralizing HIV antibodies (bNAbs) can recognize carbohydrate-dependent epitopes on gp120. In contrast to previously characterized glycan-dependent bNAbs that recognize high-mannose N-glycans, PGT121 binds complex-type N-glycans in glycan microarrays. We isolated the B-cell clone encoding PGT121, which segregates into PGT121-like and 10-1074-like groups distinguished by sequence, binding affinity, carbohydrate recognition, and neutralizing activity. Group 10-1074 exhibits remarkable potency and breadth but no detectable binding to protein-free glycans. Crystal structures of unliganded PGT121, 10-1074, and their likely germ-line precursor reveal that differential carbohydrate recognition maps to a cleft between complementarity determining region (CDR)H2 and CDRH3. This cleft was occupied by a complex-type N-glycan in a "liganded" PGT121 structure. Swapping glycan contact residues between PGT121 and 10-1074 confirmed their importance for neutralization. Although PGT121 binds complex-type N-glycans, PGT121 recognized high-mannose-only HIV envelopes in isolation and on virions. As HIV envelopes exhibit varying proportions of high-mannose- and complex-type N-glycans, these results suggest promiscuous carbohydrate interactions, an advantageous adaptation ensuring neutralization of all viruses within a given strain.
Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Anti-HIV/imunologia , Polissacarídeos/imunologia , Sequência de Aminoácidos , Substituição de Aminoácidos , Anticorpos Neutralizantes/química , Células Clonais , Cristalografia por Raios X , Epitopos/imunologia , Anticorpos Anti-HIV/química , HIV-1/imunologia , Humanos , Fragmentos Fab das Imunoglobulinas/química , Fragmentos Fab das Imunoglobulinas/imunologia , Leucócitos Mononucleares/imunologia , Ligantes , Modelos Moleculares , Dados de Sequência Molecular , Proteínas Mutantes/metabolismo , Testes de Neutralização , Polissacarídeos/química , Ligação ProteicaRESUMO
The molecular mechanisms by which γδ T cells recognize ligand remain a mystery. The non-classical MHC molecule T22 represents the best characterized ligand for murine γδ T cells, with a motif (W EGYEL) present in the γδ T cell receptor complementary-determining region 3δ (CDR3δ) loop mediating γδ T cell recognition of this molecule. Produced through V(D)J recombination, this loop is quite diverse, with different numbers and chemical types of amino acids between Trp and EGYEL, which have unknown functional consequences for T22 recognition. We have investigated the biophysical and structural effects of CDR3δ loop diversity, revealing a range of affinities for T22 but a common thermodynamic pattern. Mutagenesis of these CDR3δ loops defines the key anchor residues involved in T22 recognition as W EGYEL, similar to those found for the G8 CDR3δ loop, and demonstrates that spacer residues modulate but are not required for T22 recognition. Comparison of the location of these residues in the T22 interface reveals a striking similarity to peptide anchor residues in classically presented MHC peptides, with the key Trp residue of the CDR3δ motif completing the deficient peptide-binding groove of T22. This suggests that γδ T cell recognition of T22 utilizes the conserved ligand-presenting nature of the MHC fold.
Assuntos
Antígenos HLA/química , Peptídeos/metabolismo , Receptores de Antígenos de Linfócitos T gama-delta/metabolismo , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Regiões Determinantes de Complementaridade/química , Regiões Determinantes de Complementaridade/metabolismo , Sequência Conservada , Entropia , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese , Peptídeos/química , Ligação Proteica , Receptores de Antígenos de Linfócitos T gama-delta/química , Receptores de Antígenos de Linfócitos T gama-delta/genética , Especificidade por SubstratoRESUMO
Invariant natural killer T (iNKT) cells are innate T lymphocytes that specifically recognize α-linked glycosphingolipids (α-GSLs) as antigens presented by CD1d molecules. Activating iNKT cells by administering α-GSLs improves disease outcomes in murine cancer models and, thus, there is great interest in the clinical potential of these lipids for treating human cancers. However, humans possess several other CD1 isoforms that are not present in mice and it is not clear whether these CD1 molecules, which also bind lipids, affect human iNKT cell responses. We demonstrate here that CD1c, which is co-expressed with CD1d on blood dendritic cells and on a fraction of B cells, is able to present α-galactosylceramide (α-GalCer) as a weak agonist to human iNKT cells, and that the presence of CD1c synergistically enhances α-GalCerdependent activation of iNKT cells by CD1d. Primary human B cells expressing CD1c induced stronger iNKT cell responses to α-GalCer than the CD1c- subset, and an antibody against CD1c inhibited iNKT cell cytokine secretion. These results suggest that therapeutic activation of human iNKT cells by α-GSLs will be driven preferentially by CD1c+ cell types. Thus, B cell neoplasias that co-express CD1c and CD1d may be particularly susceptible to α-GSL therapy, and cancer vaccines using α-GSLs as adjuvants may be most effective when presented by CD1c+ antigen-presenting cells.
Assuntos
Antígenos CD1/biossíntese , Galactosilceramidas/imunologia , Glicoproteínas/biossíntese , Células T Matadoras Naturais/imunologia , Sequência de Aminoácidos , Animais , Antígenos CD1/imunologia , Antígenos CD1/metabolismo , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Glicoproteínas/imunologia , Glicoproteínas/metabolismo , Células HeLa , Humanos , Ativação Linfocitária/imunologia , Camundongos , Modelos Moleculares , Dados de Sequência Molecular , Ligação ProteicaRESUMO
ß-D-mannosyl phosphomycoketide (C32-MPM), a naturally occurring glycolipid found in the cell walls of Mycobacterium tuberculosis, acts as a potent antigen to activate T-cells upon presentation by CD1c protein. The lipid portion of C32-MPM contains a C32-mycoketide, consisting of a saturated oligoisoprenoid chain with five chiral methyl branches. Here we develop several stereocontrolled approaches to assemble the oligoisoprenoid chain with high stereopurity (>96%) using Julia-Kocienski olefinations followed by diimide reduction. By careful choice of olefination sites, we could derive all chirality from a single commercial compound, methyl (2S)-3-hydroxy-2-methylpropionate (>99% ee). Our approach is the first highly stereocontrolled method to prepare C32-MPM molecule with >96% stereopurity from a single >99% ee starting material. We anticipate that our methods will facilitate the highly stereocontrolled synthesis of a variety of other natural products containing chiral oligoisoprenoid-like chains, including vitamins, phytol, insect pheromones, and archaeal lipids.
Assuntos
Produtos Biológicos/síntese química , Glicolipídeos/síntese química , Mycobacterium tuberculosis/química , Propionatos/química , EstereoisomerismoRESUMO
Natural killer T (NKT) cells are a subset of T lymphocytes with potent immunoregulatory properties. Recognition of self-antigens presented by CD1d molecules is an important route of NKT cell activation; however, the molecular identity of specific autoantigens that stimulate human NKT cells remains unclear. Here, we have analyzed human NKT cell recognition of CD1d cellular ligands. The most clearly antigenic species was lyso-phosphatidylcholine (LPC). Diacylated phosphatidylcholine and lyso-phosphoglycerols differing in the chemistry of the head group stimulated only weak responses from human NKT cells. However, lyso-sphingomyelin, which shares the phosphocholine head group of LPC, also activated NKT cells. Antigen-presenting cells pulsed with LPC were capable of stimulating increased cytokine responses by NKT cell clones and by freshly isolated peripheral blood lymphocytes. These results demonstrate that human NKT cells recognize cholinated lyso-phospholipids as antigens presented by CD1d. Since these lyso-phospholipids serve as lipid messengers in normal physiological processes and are present at elevated levels during inflammatory responses, these findings point to a novel link between NKT cells and cellular signaling pathways that are associated with human disease pathophysiology.
Assuntos
Lisofosfatidilcolinas/imunologia , Células T Matadoras Naturais/imunologia , Apresentação de Antígeno , Células Apresentadoras de Antígenos/imunologia , Antígenos CD1d/imunologia , Autoantígenos/imunologia , Linhagem Celular , Citocinas/biossíntese , Humanos , Inflamação/imunologia , Ativação Linfocitária , Células T Matadoras Naturais/metabolismo , Fosforilcolina/análogos & derivados , Fosforilcolina/imunologia , Transdução de Sinais , Esfingosina/análogos & derivados , Esfingosina/imunologiaRESUMO
The HIV-1 envelope (Env) glycoprotein binds to host cell receptors to mediate membrane fusion. The prefusion Env trimer is stabilized by V1V2 loops that interact at the trimer apex. Broadly neutralizing antibodies (bNAbs) against V1V2 loops, exemplified by PG9, bind asymmetrically as a single Fab to the apex of the symmetric Env trimer using a protruding CDRH3 to penetrate the Env glycan shield. Here we characterized a distinct mode of V1V2 epitope recognition by the new bNAb BG1 in which two Fabs bind asymmetrically per Env trimer using a compact CDRH3. Comparisons between cryo-EM structures of Env trimer complexed with BG1 (6.2 Å resolution) and PG9 (11.5 Å resolution) revealed a new V1V2-targeting strategy by BG1. Analyses of the EM structures provided information relevant to vaccine design including molecular details for different modes of asymmetric recognition of Env trimer and a binding model for BG1 recognition of V1V2 involving glycan flexibility.
Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Anti-HIV/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Anticorpos Neutralizantes/metabolismo , Anticorpos Neutralizantes/ultraestrutura , Microscopia Crioeletrônica , Anticorpos Anti-HIV/metabolismo , Anticorpos Anti-HIV/ultraestrutura , Humanos , Fragmentos Fab das Imunoglobulinas/metabolismo , Ligação Proteica , Produtos do Gene env do Vírus da Imunodeficiência Humana/metabolismo , Produtos do Gene env do Vírus da Imunodeficiência Humana/ultraestruturaRESUMO
Since neutralizing antibodies (NAb) targeting the human cytomegalovirus (HCMV) pentamer complex (PC) potently block HCMV host cell entry, anti-PC NAb induction is thought to be important for a vaccine formulation to prevent HCMV infection. By developing a vaccine strategy based on soluble PC protein and using a previously generated Modified Vaccinia Ankara vector co-expressing all five PC subunits (MVA-PC), we compared HCMV NAb induction by homologous immunization using prime-boost vaccine regimen employing only PC protein or MVA-PC and heterologous immunization using prime-boost combinations of PC protein and MVA-PC. Utilizing a recently isolated anti-PC NAb, we produced highly pure soluble PC protein that displayed conformational and linear neutralizing epitopes, interfered with HCMV entry, and was recognized by antibodies induced by HCMV during natural infection. Mice vaccinated by different immunization routes with the purified PC protein in combination with a clinically approved adjuvant formulation elicited high-titer and durable HCMV NAb. While MVA-PC and soluble PC protein either alone or in combination elicited robust HCMV NAb, significantly different potencies of these vaccine approaches were observed in dependence on immunization schedule. Using only two immunizations, vaccination with MVA-PC alone or prime-boost combinations of MVA-PC and PC protein was significantly more effective in stimulating HCMV NAb than immunization with PC protein alone. In contrast, with three immunizations, NAb induced by soluble PC protein either alone or combined with two boosts of MVA-PC increased to levels that exceeded NAb titer stimulated by MVA-PC alone. These results provide insights into the potency of soluble protein and MVA to elicit NAb by the HCMV PC via homologous and heterologous prime-boost immunization, which may contribute to develop clinically deployable vaccine strategies to prevent HCMV infection.
Assuntos
Anticorpos Neutralizantes/imunologia , Vacinas/imunologia , Animais , Citomegalovirus/imunologia , Ensaio de Imunoadsorção Enzimática , Humanos , Camundongos , Vaccinia virus/imunologiaRESUMO
Some HIV-1-infected patients develop broad and potent HIV-1 neutralizing antibodies (bNAbs) that when passively transferred to mice or macaques can treat or prevent infection. However, bNAbs typically fail to neutralize coexisting autologous viruses due to antibody-mediated selection against sensitive viral strains. We describe an HIV-1 controller expressing HLA-B57*01 and HLA-B27*05 who maintained low viral loads for 30 years after infection and developed broad and potent serologic activity against HIV-1. Neutralization was attributed to three different bNAbs targeting nonoverlapping sites on the HIV-1 envelope trimer (Env). One of the three, BG18, an antibody directed against the glycan-V3 portion of Env, is the most potent member of this class reported to date and, as revealed by crystallography and electron microscopy, recognizes HIV-1 Env in a manner that is distinct from other bNAbs in this class. Single-genome sequencing of HIV-1 from serum samples obtained over a period of 9 years showed a diverse group of circulating viruses, 88.5% (31 of 35) of which remained sensitive to at least one of the temporally coincident autologous bNAbs and the individual's serum. Thus, bNAb-sensitive strains of HIV-1 coexist with potent neutralizing antibodies that target the virus and may contribute to control in this individual. When administered as a mix, the three bNAbs controlled viremia in HIV-1YU2-infected humanized mice. Our finding suggests that combinations of bNAbs may contribute to control of HIV-1 infection.
Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Anti-HIV/imunologia , HIV-1/imunologia , Antígenos HLA-B/imunologia , Antígeno HLA-B27/imunologia , Animais , Linfócitos B/metabolismo , Estudos de Coortes , Cristalografia por Raios X , Epitopos/imunologia , Células HEK293 , Infecções por HIV/imunologia , Humanos , Camundongos , Camundongos Transgênicos , Testes de Neutralização , Carga Viral , Viremia , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologiaRESUMO
Efforts to elicit broadly neutralizing antibodies (bNAbs) against HIV-1 require understanding germline bNAb recognition of HIV-1 envelope glycoprotein (Env). The VRC01-class bNAb family derived from the VH1-2*02 germline allele arose in multiple HIV-1-infected donors, yet targets the CD4-binding site on Env with common interactions. Modified forms of the 426c Env that activate germline-reverted B cell receptors are candidate immunogens for eliciting VRC01-class bNAbs. We present structures of germline-reverted VRC01-class bNAbs alone and complexed with 426c-based gp120 immunogens. Germline bNAb-426c gp120 complexes showed preservation of VRC01-class signature residues and gp120 contacts, but detectably different binding modes compared to mature bNAb-gp120 complexes. Unlike typical antibody-antigen interactions, VRC01-class germline antibodies exhibited preformed antigen-binding conformations for recognizing immunogens. Affinity maturation introduced substitutions increasing induced-fit recognition and electropositivity, potentially to accommodate negatively-charged complex-type N-glycans on gp120. These results provide general principles relevant to the unusual evolution of VRC01-class bNAbs and guidelines for structure-based immunogen design.
Assuntos
Anticorpos Neutralizantes/química , Anticorpos Anti-HIV/química , Antígenos HIV/química , Proteína gp120 do Envelope de HIV/química , HIV-1/química , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/metabolismo , Cristalografia por Raios X , Anticorpos Anti-HIV/imunologia , Anticorpos Anti-HIV/metabolismo , Antígenos HIV/imunologia , Antígenos HIV/metabolismo , Proteína gp120 do Envelope de HIV/imunologia , Proteína gp120 do Envelope de HIV/metabolismo , HIV-1/imunologia , Humanos , Modelos Moleculares , Ligação Proteica , Conformação ProteicaRESUMO
PURPOSE OF REVIEW: This review highlights recent developments in HIV-1 antibody engineering and discusses the effects of increased polyreactivity on serum half-lives of engineered antibodies. RECENT FINDINGS: Recent studies have uncovered a wealth of information about the relationship between the sequences and efficacies of anti-HIV-1 antibodies through a combination of bioinformatics, structural characterization and in vivo studies. This knowledge has stimulated efforts to enhance antibody breadth and potency for therapeutic use. Although some engineered antibodies have shown increased polyreactivity and short half-lives, promising efforts are circumventing these problems. SUMMARY: Antibodies are desirable as therapeutics due to their ability to recognize targets with both specificity and high affinity. Furthermore, the ability of antibodies to stimulate Fc-mediated effector functions can increase their utility. Thus, mAbs have become central to strategies for the treatment of various diseases. Using both targeted and library-based approaches, antibodies can be engineered to improve their therapeutic properties. This article will discuss recent antibody engineering efforts to improve the breadth and potency of anti-HIV-1 antibodies. The polyreactivity of engineered HIV-1 bNAbs and the effect on serum half-life will be explored along with strategies to overcome problems introduced by engineering antibodies. Finally, advances in creating bispecific anti-HIV-1 reagents are discussed.
Assuntos
Anticorpos Biespecíficos , Anticorpos Anti-HIV , Engenharia de Proteínas/métodos , Animais , Sítios de Ligação , Humanos , Camundongos , Modelos MolecularesRESUMO
Broadly neutralizing antibodies (bNAbs) to HIV-1 envelope glycoprotein (Env) can prevent infection in animal models. Characterized bNAb targets, although key to vaccine and therapeutic strategies, are currently limited. We defined a new site of vulnerability by solving structures of bNAb 8ANC195 complexed with monomeric gp120 by X-ray crystallography and trimeric Env by electron microscopy. The site includes portions of gp41 and N-linked glycans adjacent to the CD4-binding site on gp120, making 8ANC195 the first donor-derived anti-HIV-1 bNAb with an epitope spanning both Env subunits. Rather than penetrating the glycan shield by using a single variable-region CDR loop, 8ANC195 inserted its entire heavy-chain variable domain into a gap to form a large interface with gp120 glycans and regions of the gp120 inner domain not contacted by other bNAbs. By isolating additional 8ANC195 clonal variants, we identified a more potent variant, which may be valuable for therapeutic approaches using bNAb combinations with nonoverlapping epitopes.