Co-Immunization with Multimeric Scaffolds and DNA Rapidly Induces Potent Autologous HIV-1 Neutralizing Antibodies and CD8+ T Cells

Abstract

To obtain proof of concept for HIV vaccines, we generated recombinant multimeric particles displaying the HIV-1 Envelope (Env) third hypervariable region (V3) as an N-terminal fusion protein on the E2 subunit of the pyruvate dehydrogenase complex of Geobacillus stearothermophilus. The E2 scaffold self-assembles into a 60-mer core that is 24 nm in diameter, with a molecular weight of 1.5 MDa, similar to a virus like particle with up to 60 copies of a heterologous protein accessible on the surface. Env(V3)-E2 multimers were tested alone and in combination with Env(gp160) DNA in mice and rabbits. Following two or more co-immunizations with Env(V3)-E2 and Env gp160 DNA, all 18 rabbits developed potent autologous neutralizing antibodies specific for V3 in six weeks. These neutralizing antibodies were sustained for 16 weeks without boosting, and comparable responses were obtained when lipopolysaccharide, a contaminant from expression in E. coli, was removed. Co-immunizations of Env(V3)-E2 and DNA expressing gp160 elicited moderate CD8-specific responses and Env-specific antibodies in mice. Co-immunization with DNA and E2 was superior to individual or sequential vaccination with these components in eliciting both neutralizing antibodies in rabbits and CD8+ T cell responses in mice. Co-immunization with DNA and multimeric E2 scaffolds appears to offer a highly effective means of eliciting rapid, specific, and sustained immune responses that may be a useful approach for other vaccine targets.

Comprehensive Analysis of Contributions from Protein Conformational Stability and Major Histocompatibility Complex Class II-Peptide Binding Affinity to CD4+Epitope Immunogenicity in HIV-1 Envelope Glycoprotein

“…It is possible that an immunization protocol could optimize both arms of the immune response by combining stable and unstable immunogens. A similar outcome might be achieved by use of multiple formulations of the same immunogen, as has been observed in recent studies (55,56).…”

The effect of stable macromolecular complexes of ionic polyphosphazene on HIV Gag antigen and on activation of human dendritic cells and presentation to T-cells

“…As multimeric HIV complexes have demonstrated significant potential in the induction of potent immune responses [38], this formulation was selected for further studies.…”

Envelope Variants Circulating as Initial Neutralization Breadth Developed in Two HIV-Infected Subjects Stimulate Multiclade Neutralizing Antibodies in Rabbits

“…We expanded this approach to using immunogens from a subtype A-infected human subject, using a bioinformatic approach to select vaccine clones that recapitulate the evolution of quasispecies variants (48). Moreover, we also showed that coimmunization with Env-expressing plasmid DNA and recombinant Env proteins more effectively generated Env-specific antibodies in rabbits (49,50) and CD8 T cell responses in mice (49). In the current study, we built upon these recent findings and used longitudinally cloned quasispecies gp160 env genes isolated from plasma from two subjects (VC10014 and VC20013).…”