RESUMO
Broadly neutralizing monoclonal antibodies protect against infection with HIV-1 in animal models, suggesting that a vaccine that elicits these antibodies would be protective in humans. However, it has not yet been possible to induce adequate serological responses by vaccination. Here, to activate B cells that express precursors of broadly neutralizing antibodies within polyclonal repertoires, we developed an immunogen, RC1, that facilitates the recognition of the variable loop 3 (V3)-glycan patch on the envelope protein of HIV-1. RC1 conceals non-conserved immunodominant regions by the addition of glycans and/or multimerization on virus-like particles. Immunization of mice, rabbits and rhesus macaques with RC1 elicited serological responses that targeted the V3-glycan patch. Antibody cloning and cryo-electron microscopy structures of antibody-envelope complexes confirmed that immunization with RC1 expands clones of B cells that carry the anti-V3-glycan patch antibodies, which resemble precursors of human broadly neutralizing antibodies. Thus, RC1 may be a suitable priming immunogen for sequential vaccination strategies in the context of polyclonal repertoires.
Assuntos
Vacinas contra a AIDS/imunologia , Linfócitos B/imunologia , Células Clonais/imunologia , HIV-1/química , HIV-1/imunologia , Macaca mulatta/imunologia , Vacinação , Sequência de Aminoácidos , Animais , Anticorpos Neutralizantes/química , Anticorpos Neutralizantes/genética , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/ultraestrutura , Afinidade de Anticorpos , Especificidade de Anticorpos/imunologia , Complexo Antígeno-Anticorpo/imunologia , Linfócitos B/citologia , Proliferação de Células , Células Clonais/citologia , Clonagem Molecular , Apresentação Cruzada/imunologia , Microscopia Crioeletrônica , Feminino , Anticorpos Anti-HIV/química , Anticorpos Anti-HIV/genética , Anticorpos Anti-HIV/imunologia , Anticorpos Anti-HIV/ultraestrutura , Epitopos Imunodominantes/química , Epitopos Imunodominantes/imunologia , Epitopos Imunodominantes/ultraestrutura , Ativação Linfocitária , Masculino , Camundongos , Modelos Moleculares , Polissacarídeos/imunologia , Coelhos , Hipermutação Somática de ImunoglobulinaRESUMO
A small number of HIV-1-infected individuals develop broadly neutralizing antibodies to the virus (bNAbs). These antibodies are protective against infection in animal models. However, they only emerge 1-3 yr after infection, and show a number of highly unusual features including exceedingly high levels of somatic mutations. It is therefore not surprising that elicitation of protective immunity to HIV-1 has not yet been possible. Here we show that mature, primary mouse and human B cells can be edited in vitro using CRISPR/Cas9 to express mature bNAbs from the endogenous Igh locus. Moreover, edited B cells retain the ability to participate in humoral immune responses. Immunization with cognate antigen in wild-type mouse recipients of edited B cells elicits bNAb titers that neutralize HIV-1 at levels associated with protection against infection. This approach enables humoral immune responses that may be difficult to elicit by traditional immunization.