Biology subjects

Voss, J. E.

Publications and source records attributed to Voss, J. E..

11 recordsLinked to original sources

bioRxiv2021

The dengue virus NS1 protein conveys pro-inflammatory signals by docking onto human high-density lipoproteins

The nonstructural NS1 protein is a virulence factor secreted by dengue virus (DENV)-infected cells. NS1 is known to alter the complement system, activate immune cells and perturb endothelial barriers. Here we show that pro-inflammatory signals are triggered by a high affinity complex formed between NS1 and human high-density lipoproteins (HDL). Electron microscopy images of the NS1-HDL complexes show spherical HDL particles with rod-shaped NS1 protrusions on their surface. These complexes are readily detectable in the plasma of hospitalized dengue patients using anti-apolipoprotein A-I (ApoA-I) antibodies specific of the HDL moiety. The functional reprogramming of HDL particles by the NS1 protein as a means to exacerbate systemic inflammation during DENV infection provides a new paradigm linking the human lipoprotein network to dengue pathogenesis.

microbiology↗

bioRxiv2021

In vivo engineered B cells retain memory and secrete high titers of anti-HIV antibodies in mice

As a potential single-shot HIV therapy, transplanted engineered B cells allow robust secretion of broadly neutralizing antibodies (bNAbs). However, ex vivo engineering of autologous B cells is expensive and requires specialized facilities, while allogeneic B cell therapy necessitates MHC compatibility. Here, we develop in vivo B cell engineering, by injecting two adeno associated viral vectors, one coding for saCas9 and another coding for a bNAb. Following immunizations, we demonstrate memory retention and bNAb secretion at neutralizing titers. We observed minimal CRISPR/Cas9 off-target cleavage, using unbiased CHANGE-Seq analysis, while on-target cleavage at undesired tissues is reduced by expressing saCas9 from a B cell specific promoter. In vivo B cell engineering is thus a safe, potent and scalable method for expressing desired antibodies against HIV and beyond. One sentence summaryB cells can be engineered in vivo to robustly secrete anti-HIV bNAbs in a safe, durable and scalable manner.

immunology↗

bioRxiv2020

An Engineered Antibody with Broad Protective Efficacy in Murine Models of SARS and COVID-19

The recurrent zoonotic spillover of coronaviruses (CoVs) into the human population underscores the need for broadly active countermeasures. Here, we employed a directed evolution approach to engineer three SARS-CoV-2 antibodies for enhanced neutralization breadth and potency. One of the affinity-matured variants, ADG-2, displays strong binding activity to a large panel of sarbecovirus receptor binding domains (RBDs) and neutralizes representative epidemic sarbecoviruses with remarkable potency. Structural and biochemical studies demonstrate that ADG-2 employs a unique angle of approach to recognize a highly conserved epitope overlapping the receptor binding site. In murine models of SARS-CoV and SARS-CoV-2 infection, passive transfer of ADG-2 provided complete protection against respiratory burden, viral replication in the lungs, and lung pathology. Altogether, ADG-2 represents a promising broad-spectrum therapeutic candidate for the treatment and prevention of SARS-CoV-2 and future emerging SARS-like CoVs.

immunology↗

bioRxiv2020

Cross-reactive serum and memory B cell responses to spike protein in SARS-CoV-2 and endemic coronavirus infection

Pre-existing immune responses to seasonal endemic coronaviruses could have profound consequences for antibody responses to SARS-CoV-2, either induced in natural infection or through vaccination. Such consequences are well established in the influenza and flavivirus fields. A first step to establish whether pre-existing responses can impact SARS-CoV-2 infection is to understand the nature and extent of cross-reactivity in humans to coronaviruses. We compared serum antibody and memory B cell responses to coronavirus spike (S) proteins from pre-pandemic and SARS-CoV-2 convalescent donors using a series of binding and functional assays. We found weak evidence of pre-existing SARS-CoV-2 cross-reactive serum antibodies in pre-pandemic donors. However, we found stronger evidence of pre-existing cross-reactive memory B cells that were activated on SARS-CoV-2 infection. Monoclonal antibodies (mAbs) isolated from the donors showed varying degrees of cross-reactivity with betacoronaviruses, including SARS and endemic coronaviruses. None of the cross-reactive mAbs were neutralizing except for one that targeted the S2 subunit of the S protein. The results suggest that pre-existing immunity to endemic coronaviruses should be considered in evaluating antibody responses to SARS-CoV-2.

immunology↗

bioRxiv2020

Broad sarbecovirus neutralizing antibodies define a key site of vulnerability on the SARS-CoV-2 spike protein

Broadly protective vaccines against known and pre-emergent coronaviruses are urgently needed. Critical to their development is a deeper understanding of cross-neutralizing antibody responses induced by natural human coronavirus (HCoV) infections. Here, we mined the memory B cell repertoire of a convalescent SARS donor and identified 200 SARS-CoV-2 binding antibodies that target multiple conserved sites on the spike (S) protein. A large proportion of the antibodies display high levels of somatic hypermutation and cross-react with circulating HCoVs, suggesting recall of pre-existing memory B cells (MBCs) elicited by prior HCoV infections. Several antibodies potently cross-neutralize SARS-CoV, SARS-CoV-2, and the bat SARS-like virus WIV1 by blocking receptor attachment and inducing S1 shedding. These antibodies represent promising candidates for therapeutic intervention and reveal a new target for the rational design of pan-sarbecovirus vaccines.

immunology↗

bioRxiv2020

Rapid isolation of potent SARS-CoV-2 neutralizing antibodies and protection in a small animal model

The development of countermeasures to prevent and treat COVID-19 is a global health priority. In under 7 weeks, we enrolled a cohort of SARS-CoV-2-recovered participants, developed neutralization assays to interrogate serum and monoclonal antibody responses, adapted our high throughput antibody isolation, production and characterization pipeline to rapidly screen over 1000 antigen-specific antibodies, and established an animal model to test protection. We report multiple highly potent neutralizing antibodies (nAbs) and show that passive transfer of a nAb provides protection against high-dose SARS-CoV-2 challenge in Syrian hamsters. The study suggests a role for nAbs in prophylaxis, and potentially therapy, of COVID-19. The nAbs define protective epitopes to guide vaccine design.

immunology↗

bioRxiv2020

Vaccine Elicitation of HIV Broadly Neutralizing Antibodies from Engineered B cells

HIV broadly neutralizing antibodies (bnAbs) can suppress viremia and protect against infection1. However, their elicitation is made difficult by low frequencies of appropriate precursor B cell receptors and the complex maturation pathways required to generate bnAbs from these precursors2. Antibody genes can be engineered into B cells for expression as both a functional receptor on cell surfaces and as secreted antibody3-5. Here, we show that HIV bnAb-engineered primary mouse B cells can be adoptively transferred and vaccinated in immunocompetent wild-type animals resulting in the expansion of durable bnAb memory and long-lived plasma cells. Somatic hypermutation after immunization indicated that engineered cells have the capacity to respond to an evolving pathogen. These results encourage further exploration of engineered B cell vaccines as a strategy for durable elicitation of HIV bnAbs to protect against infection and as a contributor to a functional cure.

immunology↗

bioRxiv2020

B cells expressing authentic naive human VRC01-class BCRs can be primed and recruited to germinal centers in multiple independent mouse models

Animal models of human antigen-specific B cell receptors (BCR) generally depend on "inferred germline" sequences, and thus their relationship to authentic naive human B cell BCR sequences and affinities is unclear. Here, BCR sequences from authentic naive human VRC01-class B cells from healthy human donors were selected for the generation of three new BCR knock-in mice. The BCRs span the physiological range of affinities found in humans, and use three different light chains (VK3-20, VK1-5, and VK1-33) found among subclasses of naive human VRC01-class B cells and HIV broadly neutralizing antibodies (bnAbs). The germline-targeting HIV immunogen eOD-GT8 60mer is currently in clinical trial as a candidate bnAb vaccine priming immunogen. To attempt to model human immune responses to the eOD-GT8 60mer, we tested each authentic naive human VRC01-class BCR mouse model under rare human physiological B cell precursor frequency conditions. B cells with high (HuGL18HL) or medium (HuGL17HL) affinity BCRs were primed, recruited to germinal centers, accrued substantial somatic hypermutation, and formed memory B cells. Precursor frequency and affinity interdependently influenced responses. Taken together, these experiments utilizing authentic naive human VRC01-class BCRs validate a central tenet of germline-targeting vaccine design and extend the overall concept of the reverse vaccinology approach to vaccine development.

immunology↗

bioRxiv2019

HIV Envelope Trimer-Elicited Autologous Neutralizing Antibodies Bind a Region Overlapping the N332 Glycan Supersite

To date, immunization studies of rabbits with the BG505 SOSIP.664 HIV envelope glycoprotein trimers have revealed the 241/289 glycan hole as the dominant neutralizing antibody epitope. Here, we isolated monoclonal antibodies from a rabbit that did not exhibit glycan hole-dependent autologous serum neutralization. The antibodies did not compete with a previously isolated glycan hole-specific antibody but did compete with N332 glycan supersite broadly neutralizing antibodies. A high resolution cryoEM structure of one of the antibodies in complex with the BG505 SOSIP.664 trimer demonstrated that, while the epitope recognized overlapped with the N332 glycan supersite by contacting the GDIR motif at the base of V3, the primary contacts were located in the variable V1 loop. These data suggest that strain-specific responses to V1 may interfere with broadly neutralizing responses to the N332 glycan supersite and vaccine immunogens may require engineering to minimize these off-target responses or steer them toward a more desirable pathway.

immunology↗

bioRxiv2019

Neutralizing antibody responses to an HIV envelope glycan hole are not easily broadened

Extensive studies with subtype A BG505-derived HIV envelope glycoprotein (Env) SOSIP immunogens have revealed that the dominant autologous neutralizing site in rabbits is located in an exposed region of the heavily glycosylated trimer that lacks potential N-linked glycosylation sites at positions 230, 241, and 289. The Env derived from B41, a subtype B virus, shares a glycan hole centered on positions 230 and 289. BG505 and B41 SOSIP immunogens were combined to test whether immunization in rabbits could induce broader Tier 2 neutralizing responses to the common glycan hole shared between BG505 and B41. Here we isolated autologous neutralizing antibodies (nAbs) that were induced by immunization with B41 SOSIP alone, as well as B41 and BG505 co-immunization, and describe their structure in complex with the B41 SOSIP trimer. Our data suggest that distinct autologous nAb lineages are induced by BG505 and B41 immunogens, even when both immunogens were administered together. In contrast to previously described BG505 glycan hole antibodies, the B41-specific nAbs accommodate the highly conserved N241 glycan (>97% conserved), which is present in B41. Single particle cryo-electron microscopy (cryoEM) studies confirmed that B41 and BG505-specific nAbs bind to overlapping glycan hole epitopes. In an attempt to broaden the reactivity of a B41-specific nAb, mutations in the BG505 glycan hole epitope guided by our high-resolution data only recovered partial binding. Overall, designing prime-boost immunogens to increase the breath of nAb responses directed at glycan holes epitopes remains challenging even when the typically immunodominant glycan holes despite overlap with different Envs.\n\nIMPORTANCEA glycan hole is one of the most dominant autologous neutralizing epitopes targeted on BG505 and B41 SOSIP trimer immunized rabbits. Our high-resolution cryoEM studies of B41 in complex with a B41-specific antibody complex elucidate the molecular basis of this strain-specific glycan hole response. We conclude that eliciting cross-reactive responses to this region would likely require hybrid immunogens that bridge between BG505 and B41.

immunology↗

bioRxiv2018

Reprogramming the antigen specificity of B cells using genome-editing technologies

We have developed a method to introduce novel paratopes into the human antibody repertoire by modifying the immunoglobulin genes of mature B cells directly using genome editing technologies. We used CRISPR-Cas9 in a homology directed repair strategy, to replace the heavy chain (HC) variable region in B cell lines with that from an HIV broadly neutralizing antibody, PG9. Our strategy is designed to function in cells that have undergone VDJ recombination using any combination of variable (V), diversity (D) and joining (J) genes. The modified locus expresses PG9 HC which pairs with native light chains resulting in the cell surface expression of HIV specific B cell receptors (BCRs). Endogenous activation-induced cytidine deaminase (AID) in engineered cells allowed for Ig class switching and generated BCR variants with improved anti-HIV neutralizing activity. Thus, BCRs engineered in this way retain the genetic flexibility normally required for affinity maturation during adaptive immune responses.

immunology↗