ABSTRACT
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.
Subject(s)
AIDS Vaccines/immunology , B-Lymphocytes/immunology , Clone Cells/immunology , HIV-1/chemistry , HIV-1/immunology , Macaca mulatta/immunology , Vaccination , Amino Acid Sequence , Animals , Antibodies, Neutralizing/chemistry , Antibodies, Neutralizing/genetics , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/ultrastructure , Antibody Affinity , Antibody Specificity/immunology , Antigen-Antibody Complex/immunology , B-Lymphocytes/cytology , Cell Proliferation , Clone Cells/cytology , Cloning, Molecular , Cross-Priming/immunology , Cryoelectron Microscopy , Female , HIV Antibodies/chemistry , HIV Antibodies/genetics , HIV Antibodies/immunology , HIV Antibodies/ultrastructure , Immunodominant Epitopes/chemistry , Immunodominant Epitopes/immunology , Immunodominant Epitopes/ultrastructure , Lymphocyte Activation , Male , Mice , Models, Molecular , Polysaccharides/immunology , Rabbits , Somatic Hypermutation, ImmunoglobulinABSTRACT
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.
