RESUMO
The vaccine-mediated elicitation of antibodies (Abs) capable of neutralizing diverse HIV-1 strains has been a long-standing goal. To understand how broadly neutralizing antibodies (bNAbs) can be elicited, we identified, characterized, and tracked five neutralizing Ab lineages targeting the HIV-1-fusion peptide (FP) in vaccinated macaques over time. Genetic and structural analyses revealed two of these lineages to belong to a reproducible class capable of neutralizing up to 59% of 208 diverse viral strains. B cell analysis indicated each of the five lineages to have been initiated and expanded by FP-carrier priming, with envelope (Env)-trimer boosts inducing cross-reactive neutralization. These Abs had binding-energy hotspots focused on FP, whereas several FP-directed Abs induced by immunization with Env trimer-only were less FP-focused and less broadly neutralizing. Priming with a conserved subregion, such as FP, can thus induce Abs with binding-energy hotspots coincident with the target subregion and capable of broad neutralization.
Assuntos
Vacinas contra a AIDS/imunologia , Anticorpos Neutralizantes/imunologia , Anticorpos Anti-HIV/imunologia , Peptídeos/imunologia , Sequência de Aminoácidos , Animais , Anticorpos Neutralizantes/química , Anticorpos Neutralizantes/classificação , Linfócitos B/citologia , Linfócitos B/metabolismo , Cristalografia por Raios X , Feminino , Células HEK293 , Anticorpos Anti-HIV/química , Anticorpos Anti-HIV/classificação , HIV-1/metabolismo , Humanos , Macaca mulatta , Masculino , Peptídeos/química , Estrutura Terciária de Proteína , Produtos do Gene env do Vírus da Imunodeficiência Humana/química , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/metabolismoRESUMO
A central goal of HIV-1 vaccine research is the elicitation of antibodies capable of neutralizing diverse primary isolates of HIV-1. Here we show that focusing the immune response to exposed N-terminal residues of the fusion peptide, a critical component of the viral entry machinery and the epitope of antibodies elicited by HIV-1 infection, through immunization with fusion peptide-coupled carriers and prefusion stabilized envelope trimers, induces cross-clade neutralizing responses. In mice, these immunogens elicited monoclonal antibodies capable of neutralizing up to 31% of a cross-clade panel of 208 HIV-1 strains. Crystal and cryoelectron microscopy structures of these antibodies revealed fusion peptide conformational diversity as a molecular explanation for the cross-clade neutralization. Immunization of guinea pigs and rhesus macaques induced similarly broad fusion peptide-directed neutralizing responses, suggesting translatability. The N terminus of the HIV-1 fusion peptide is thus a promising target of vaccine efforts aimed at eliciting broadly neutralizing antibodies.
Assuntos
Vacinas contra a AIDS/imunologia , Anticorpos Neutralizantes/imunologia , Epitopos/imunologia , Anticorpos Anti-HIV/imunologia , HIV-1/imunologia , Peptídeos/farmacologia , Proteínas Recombinantes de Fusão/farmacologia , Sequência de Aminoácidos , Animais , Feminino , Cobaias , HIV-1/efeitos dos fármacos , Imunização , Macaca mulatta , Camundongos Endogâmicos C57BL , Modelos Moleculares , Testes de Neutralização , Produtos do Gene env do Vírus da Imunodeficiência Humana/química , Produtos do Gene env do Vírus da Imunodeficiência Humana/metabolismoRESUMO
The HIV-1 fusion peptide, comprising 15 to 20 hydrophobic residues at the N terminus of the Env-gp41 subunit, is a critical component of the virus-cell entry machinery. Here, we report the identification of a neutralizing antibody, N123-VRC34.01, which targets the fusion peptide and blocks viral entry by inhibiting conformational changes in gp120 and gp41 subunits of Env required for entry. Crystal structures of N123-VRC34.01 liganded to the fusion peptide, and to the full Env trimer, revealed an epitope consisting of the N-terminal eight residues of the gp41 fusion peptide and glycan N88 of gp120, and molecular dynamics showed that the N-terminal portion of the fusion peptide can be solvent-exposed. These results reveal the fusion peptide to be a neutralizing antibody epitope and thus a target for vaccine design.