CryoEM Structures of Antibodies Elicited by Germline-Targeting HIV MPER Epitope-Scaffolds.

Applying cryoEM to small protein complexes is usually challenging due to their lack of features for particle alignment. Here, we characterized antibody responses to 21 kDa HIV membrane-proximal external region germline-targeting (MPER-GT) immunogens through cryoEM by complexing them with 10E8 or Fabs derived from MPER-GT immunized animals. Distinct antibody-antigen interactions were analyzed using atomic models generated from cryoEM maps.

A modification to heptad repeat 1 of gp41 improves yield and/or quality of soluble pre-fusion HIV-1 envelope glycoprotein trimers.

Unlabelled: Native-like HIV-1 envelope glycoprotein (Env) trimers, exemplified by the SOSIP design, are widely used as immunogens, analytical antigens, and for structural studies. These vaccine research and development programs require trimers that are based on multiple HIV-1 genotypes. While a wide range of protein engineering strategies can produce SOSIP trimers from most Env gene sequences, there are still examples of trimers that are expressed only at impractically low yields or that are unstable.

HIV broadly neutralizing antibody precursors to the Apex epitope induced in nonhuman primates.

An effective prophylactic HIV vaccine will likely need to induce broadly neutralizing antibodies (bnAbs). bnAbs to the Apex region of the HIV envelope glycoprotein (Env) are promising targets for vaccination because of their relatively low somatic hypermutation compared with other bnAbs. Most Apex bnAbs engage Env using an exceptionally long heavy-chain complementarity-determining region 3 (HCDR3) containing specific binding motifs, which reduces bnAb precursor frequency and makes priming of rare bnAb precursors a likely limiting step in the path to Apex bnAb induction.

Immunofocusing on the conserved fusion peptide of HIV envelope glycoprotein in rhesus macaques.

During infection, the fusion peptide (FP) of HIV envelope glycoprotein (Env) serves a central role in viral fusion with the host cell. As such, the FP is highly conserved and therefore an attractive epitope for vaccine design. Here, we describe a vaccination study in non-human primates (NHPs) where glycan deletions were made on soluble HIV Env to increase FP epitope exposure.

Accelerated cGMP production of near-native HIV-1 Env trimers following electroporation transfection and immunogenicity analysis.

Evaluation of recombinant HIV-1 surface glycoproteins (Env) as vaccine candidates for Phase I human experimental trials often requires production of cGMP-grade well-ordered Env trimers. Here, we report an accelerated cGMP compatible approach for expression and purification of a stabilized HIV clade C-derived trimer '16055 DG4 NFL' (for native flexibly linked). This recombinant trimer was expressed from CHO-S™ cells using a MaxCyte® VLX™ electroporation-based transient transfection process.

Vaccination with mRNA-encoded membrane-anchored HIV envelope trimers elicited tier 2 neutralizing antibodies in a phase 1 clinical trial.

mRNA technology might accelerate development of an urgently needed preventive human immunodeficiency virus (HIV) vaccine. We evaluated the safety and immunogenicity of three mRNA-encoded envelope trimers, including two doses of soluble and membrane-anchored forms, in a randomized, open-label, phase 1 clinical trial. Vaccines were generally well tolerated, although 6.

Vaccination with an mRNA-encoded membrane-bound HIV envelope trimer induces neutralizing antibodies in animal models.

A protective vaccine against human immunodeficiency virus (HIV) will likely need to induce broadly neutralizing antibodies (bnAbs) that engage relatively conserved epitopes on the HIV envelope glycoprotein (Env) trimer. Nearly all vaccine strategies to induce bnAbs require the use of complex immunization regimens involving a series of different immunogens, most of which are Env trimers. Producing protein-based clinical material to evaluate such relatively complex regimens in humans presents major challenges in cost and time.

Virus glycoprotein nanodisc platform for vaccine design.

Transmembrane glycoproteins of enveloped viruses are the targets of neutralizing antibodies and essential vaccine antigens. mRNA-LNP technology allows in situ production of transmembrane glycoproteins upon immunization, but biophysical characterization of transmembrane antigens and in vitro analysis of post-immunization antibody responses typically rely on soluble proteins. Here, we present a methodological platform for assembling transmembrane glycoprotein vaccine candidates into lipid nanodiscs.

Replaying germinal center evolution on a quantified affinity landscape.

Darwinian evolution of immunoglobulin genes within germinal centers (GC) underlies the progressive increase in antibody affinity following antigen exposure. Whereas the mechanics of how competition between GC B cells drives increased affinity are well established, the dynamical evolutionary features of this process remain poorly characterized. We devised an experimental evolution model in which we "replay" over one hundred instances of a clonally homogenous GC reaction and follow the selective process by assigning affinities to all cells using deep mutational scanning.

Vaccines combining slow release and follicle targeting of antigens increase germinal center B cell diversity and clonal expansion.

Vaccine adjuvants play important roles in shaping the humoral response to immunization. Here, we analyzed mechanisms of action of a clinically relevant combination adjuvant strategy, where phosphoserine (pSer)-tagged immunogens bound to aluminum hydroxide (alum) adjuvant, promoting prolonged antigen release to draining lymph nodes, are combined with a saponin nanoparticle adjuvant termed SMNP, which alters lymph flow and antigen entry into lymph nodes. When used with a stabilized HIV envelope trimer antigen in mice, this combined adjuvant approach promoted substantial enhancements in germinal center and antibody responses relative to either adjuvant alone.

Germline-targeting HIV Envelope SOSIP immunization more frequently elicits broadly-neutralizing antibody precursor responses in infant compared to juvenile rhesus macaques.

A vaccine capable of inducing broadly neutralizing antibodies (bnAbs) is essential for effective prevention against HIV in children and adolescents. Germline-targeting vaccine strategies aim to stimulate bnAb precursor B cells through carefully designed immunogens, such as the stabilized SOSIP trimers, which mimic native HIV envelope (Env) proteins while presenting key neutralizing epitopes to germline B cell receptors. Given the ability of children living with HIV to develop bnAbs earlier and at a higher frequency than adults, we compared the immunogenicity of a CD4 binding site (CD4bs) bnAb germline-targeting SOSIP trimer immunization strategy in infant (n = 5) and juvenile (n = 4) rhesus macaques (RMs).

Microfluidics combined with electron microscopy for rapid and high-throughput mapping of antibody-viral glycoprotein complexes.

Understanding the mechanistic interplay between antibodies and invading pathogens is essential for vaccine development. Current methods are labour and time intensive and limited by sample preparation bottlenecks. Here we present microfluidic electron microscopy-based polyclonal epitope mapping (mEM), which combines microfluidics with single-particle electron microscopy for the structural characterization of immune complexes using small volumes of sera (<4 µl).

Antigen persistence and TLR stimulation contribute to induction of a durable HIV-1-specific neutralizing antibody response.

HIV-1 Env glycoprotein (Env) immunogenicity is limited in part by structural instability and extensive glycan shielding and is likely the greatest obstacle to an HIV-1 vaccine. Stabilized Env trimers can elicit serum neutralizing antibodies, but the response is short-lived. Here we use Newcastle Disease Virus-like particle (NDV-VLP) platform to present stabilized versions of HIV-1 Env at high valency and in the context of varied conformational stability, adjuvants, dose, and antigen persistence.

Precise targeting of HIV broadly neutralizing antibody precursors in humans.

A protective HIV vaccine will need to induce broadly neutralizing antibodies (bnAbs) in humans, but priming rare bnAb precursor B cells has been challenging. In a double-blinded, placebo-controlled phase 1 human clinical trial, the recombinant, germline-targeting envelope glycoprotein (Env) trimer BG505 SOSIP.v4.

Vaccination with mRNA-encoded nanoparticles drives early maturation of HIV bnAb precursors in humans.

A leading HIV vaccine strategy requires a priming immunogen to induce broadly neutralizing antibody (bnAb) precursors, followed by a series of heterologous boosters to elicit somatic hypermutation (SHM) and produce bnAbs. In two randomized, open-label phase 1 human clinical trials, IAVI G002 in the United States and IAVI G003 in Rwanda and South Africa (IAVI, International Aids Vaccine Initiative), we evaluated the safety and immunogenicity of mRNA-encoded nanoparticles as priming immunogens (both trials) and first-boosting immunogens (IAVI G002). The vaccines were generally safe and well tolerated, except that 18% of IAVI G002 participants experienced skin reactions.

Vaccination of nonhuman primates elicits a broadly neutralizing antibody lineage targeting a quaternary epitope on the HIV-1 Env trimer.

The elicitation of cross-neutralizing antibodies to the HIV-1 envelope glycoprotein (Env) by vaccination remains a major challenge. Here, we immunized previously Env-immunized nonhuman primates with a series of near-native trimers that possessed N-glycan deletions proximal to the conserved CD4 binding site (CD4bs) to focus B cells to this region. Following heterologous boosting with fully glycosylated trimers, we detected tier 2 cross-neutralizing activity in the serum of several animals.

Molecular parameters governing antibody FcγR signaling and effector functions in the context of HIV envelope.

Antibody effector functions contribute to the immune response to pathogens and can influence the efficacy of antibodies as therapeutics. To date, however, there is limited information on the molecular parameters that govern fragment crystallizable (Fc) effector functions. In this study, using AI-assisted protein design, the influences of binding kinetics, epitope location, and stoichiometry of binding on cellular Fc effector functions were investigated using engineered HIV-1 envelope as a model antigen.

Vaccination with mRNA-encoded membrane-bound HIV Envelope trimer induces neutralizing antibodies in animal models.

A protective vaccine against HIV will likely need to induce broadly neutralizing antibodies (bnAbs) that engage relatively conserved epitopes on the HIV envelope glycoprotein (Env) trimer. Nearly all vaccine strategies to induce bnAbs require the use of relatively complex immunization regimens involving a series of different immunogens, most of which are Env trimers. Producing protein-based clinical material to evaluate such relatively complex regimens in humans presents major challenges in cost and time.

Polyfunctionality and breadth of HIV-1 antibodies are associated with delayed disease progression.

HIV-1 infection leads to chronic disease requiring life-long treatment and therefore alternative therapeutics, a cure and/or a protective vaccine are needed. Antibody-mediated effector functions could have a role in the fight against HIV-1. However, the properties underlying the potential beneficial effects of antibodies during HIV-1 infection are poorly understood.

Immunofocusing on the conserved fusion peptide of HIV envelope glycoprotein in rhesus macaques.

During infection, the fusion peptide (FP) of HIV envelope glycoprotein (Env) serves a central role in viral fusion with the host cell. As such, the FP is highly conserved and therefore an attractive epitope for vaccine design. Here, we describe a vaccination study in non-human primates (NHPs) where glycan deletions were made on soluble HIV Env to increase FP epitope exposure.

Plant-produced SARS-CoV-2 antibody engineered towards enhanced potency and in vivo efficacy.

Prevention of severe COVID-19 disease by SARS-CoV-2 in high-risk patients, such as immuno-compromised individuals, can be achieved by administration of antibody prophylaxis, but producing antibodies can be costly. Plant expression platforms allow substantial lower production costs compared to traditional bio-manufacturing platforms depending on mammalian cells in bioreactors. In this study, we describe the expression, production and purification of the originally human COVA2-15 antibody in plants.

Mosaic and mixed HIV-1 glycoprotein nanoparticles elicit antibody responses to broadly neutralizing epitopes.

An effective human immunodeficiency virus 1 (HIV-1) vaccine will most likely have to elicit broadly neutralizing antibodies (bNAbs) to overcome the sequence diversity of the envelope glycoprotein (Env). So far, stabilized versions of Env, such as SOSIP trimers, have been able to induce neutralizing antibody (NAb) responses, but those responses are mainly strain-specific. Here we attempted to broaden NAb responses by using a multivalent vaccine and applying a number of design improvements.

Use of 3M-052-AF with Alum adjuvant in HIV trimer vaccine induces human autologous neutralizing antibodies.

Stabilized trimers preserving the native-like HIV envelope structure may be key components of a preventive HIV vaccine regimen to induce broadly neutralizing antibodies (bnAbs). We evaluated trimeric BG505 SOSIP.664 gp140 formulated with a novel TLR7/8 signaling adjuvant, 3M-052-AF/Alum, for safety, adjuvant dose-finding, and immunogenicity in a first-in-healthy adult (n = 17), randomized, and placebo-controlled trial (HVTN 137A).

Vaccines combining slow delivery and follicle targeting of antigens increase germinal center B cell clonal diversity and clonal expansion.

Vaccines incorporating slow delivery, multivalent antigen display, or immunomodulation through adjuvants have an important role to play in shaping the humoral immune response. Here we analyzed mechanisms of action of a clinically relevant combination adjuvant strategy, where phosphoserine (pSer)-tagged immunogens bound to aluminum hydroxide (alum) adjuvant (promoting prolonged antigen delivery to draining lymph nodes) are combined with a potent saponin nanoparticle adjuvant termed SMNP (which alters lymph flow and antigen entry into lymph nodes). When employed with a stabilized HIV Env trimer antigen in mice, this combined adjuvant approach promoted substantial enhancements in germinal center (GC) and antibody responses relative to either adjuvant alone.