Design and Functional Characterization of HIV-1 Envelope Protein-Coupled T Helper Liposomes.

Functionalization of experimental HIV-1 virus-like particle vaccines with heterologous T helper epitopes (T helper VLPs) can modulate the humoral immune response via intrastructural help (ISH). Current advances in the conjugation of native-like HIV-1 envelope trimers (Env) onto liposomes and encapsulation of peptide epitopes into these nanoparticles renders this GMP-scalable liposomal platform a feasible alternative to VLP-based vaccines. In this study, we designed and analyzed customizable Env-conjugated T helper liposomes.

Covalent Linkage of HIV-1 Trimers to Synthetic Liposomes Elicits Improved B Cell and Antibody Responses.

We have demonstrated that a liposomal array of well-ordered trimers enhances B cell activation, germinal center formation, and the elicitation of tier-2 autologous neutralizing antibodies. Previously, we coupled well-ordered cleavage-independent NFL trimers via their C-terminal polyhistidine tails to nickel lipids integrated into the lipid bilayer. Despite favorable effects, concern remained over the potentially longer-term instability of noncovalent linkage of the trimers to the liposomes.

Particulate Array of Well-Ordered HIV Clade C Env Trimers Elicits Neutralizing Antibodies that Display a Unique V2 Cap Approach.

The development of soluble envelope glycoprotein (Env) mimetics displaying ordered trimeric symmetry has ushered in a new era in HIV-1 vaccination. The recently reported native, flexibly linked (NFL) design allows the generation of native-like trimers from clinical isolates at high yields and homogeneity. As the majority of infections world-wide are of the clade C subtype, we examined responses in non-human primates to well-ordered subtype C 16055 trimers administered in soluble or high-density liposomal formats.

Dense Array of Spikes on HIV-1 Virion Particles.

HIV-1 is rare among viruses for having a low number of envelope glycoprotein (Env) spikes per virion, i.e., ∼7 to 14.

High-Density Array of Well-Ordered HIV-1 Spikes on Synthetic Liposomal Nanoparticles Efficiently Activate B Cells.

A major step toward an HIV-1 vaccine is an immunogen capable of inducing neutralizing antibodies. Envelope glycoprotein (Env) mimetics, such as the NFL and SOSIP designs, generate native-like, well-ordered trimers and elicit tier 2 homologous neutralization (SOSIPs). We reasoned that the display of well-ordered trimers by high-density, particulate array would increase B cell activation compared to soluble trimers.

HIV-1 Vaccine-elicited Antibodies Reverted to Their Inferred Naive Germline Reveal Associations between Binding Affinity and in vivo Activation.

The elicitation of HIV-1 broadly neutralizing antibodies following envelope glycoprotein (Env) vaccination is exceedingly difficult. Suboptimal engagement of naïve B cells is suggested to limit these low frequency events, especially at the conserved CD4bs. Here, we analyzed CD4bs-directed monoclonal antibodies (mAbs) elicited by YU2 gp140-foldon trimers in a non-human primate by selective sorting using CD4bs "knock out" trimers.

Kinetic Analysis of Monoclonal Antibody Binding to HIV-1 gp120-derived Hyperglycosylated Cores.

Kinetic analysis of antibodies is one of the important study for characterization of antibodies and screening of ligands. In our recent study, we compared the antigenic profiles and binding characteristics of four HIV-1 envelope glycoprotein (Env) core immunogens using multiple monoclonal antibodies by Bio-Layer Light Interferometry (BLI). This technology enables real-time analysis of interactions on the surface of a fiber optic biosensor by accurately measuring kinetic constants such as K, K, and K in a 96-well format.

Coupling of HIV-1 gp120-derived Core Protein to Paramagnetic Beads and Adsorption Assays.

Analysis of the functional activity in polyclonal serum following immunization of a complex protein or glycoprotein immunogen is a very important but tedious process. Fine mapping of epitope specific antibodies is difficult when they are elicited at relatively low levels. In our recent study focused at developing an HIV-1 vaccine, we immunized rabbits with hyperglycosylated stable core immunogens, which were designed using high resolution structural information to elicit antibodies against the primary receptor-binding, CD4-binding site on HIV-1 gp120.

Diverse antibody genetic and recognition properties revealed following HIV-1 envelope glycoprotein immunization.

Isolation of mAbs elicited by vaccination provides opportunities to define the development of effective immunity. Ab responses elicited by current HIV-1 envelope glycoprotein (Env) immunogens display narrow neutralizing activity with limited capacity to block infection by tier 2 viruses. Intense work in the field suggests that improved Env immunogens are forthcoming, and it is therefore important to concurrently develop approaches to investigate the quality of vaccine-elicited responses at a higher level of resolution.

Hyperglycosylated stable core immunogens designed to present the CD4 binding site are preferentially recognized by broadly neutralizing antibodies.

Unlabelled: The HIV-1 surface envelope glycoprotein (Env) trimer mediates entry into CD4(+) CCR5(+) host cells. Env possesses conserved antigenic determinants, such as the gp120 primary receptor CD4 binding site (CD4bs), a known neutralization target. Env also contains variable regions and protein surfaces occluded within the trimer that elicit nonneutralizing antibodies.