Publications by authors named "Sewall L"

Vaccination strategies against HIV-1 aim to elicit broadly neutralizing antibodies (bnAbs) using prime-boost regimens with HIV envelope (Env) immunogens. Epitope mapping has shown that early antibody responses are directed to easily accessible nonneutralizing epitopes on Env instead of bnAb epitopes. Autologously neutralizing antibody responses appear upon boosting, once immunodominant epitopes are saturated.

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Current COVID-19 vaccines are largely limited in their ability to induce broad, durable immunity against emerging viral variants. Design and development of improved vaccines utilizing existing platforms requires an in-depth understanding of the antigenic and immunogenic properties of available vaccines. Here we examined the antigenicity of two of the original COVID-19 vaccines, mRNA-1273 and NVX-CoV2373, by electron microscopy-based polyclonal epitope mapping (EMPEM) of serum from immunized non-human primates (NHPs) and clinical trial donors.

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Article Synopsis
  • - The study focuses on generating broadly neutralizing antibodies (bnAbs) against HIV's Envelope (Env) by immunizing cows, which show a reliable response compared to common animal models.
  • - Two groups of cows were given different regimens of V2-apex focusing immunogens, resulting in some cows producing serum neutralizing antibodies specifically targeting the V2-apex region of Env.
  • - The successful isolation of bnAbs from the cows, particularly those with ultralong CDRH3 regions, indicates that these antibodies are more effective in responding to highly glycosylated proteins like HIV Env.
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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).

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Adolescents are a growing population of people living with HIV. The period between weaning and sexual debut presents a low-risk window for HIV acquisition, making early childhood an ideal time for implementing an immunization regimen. Because the elicitation of broadly neutralizing antibodies (bnAbs) is critical for an effective HIV vaccine, our goal was to assess the ability of a bnAb B cell lineage-designed HIV envelope SOSIP (protein stabilized by a disulfide bond between gp120-gp41-named "SOS"-and an isoleucine-to-proline point mutation-named "IP"-at residue 559) to induce precursor CD4 binding site (CD4bs)-targeting bnAbs in early life.

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Article Synopsis
  • Immunodominance of antibodies targeting non-neutralizing epitopes and high somatic hypermutation in germinal centers (GCs) are major challenges in developing a successful HIV vaccine.
  • The study utilized implantable osmotic pumps to deliver epitope-targeted immunogens to rhesus macaques, aiming to enhance antibody responses against the conserved fusion peptide over six months.
  • Results indicated that while antibody responses against the FP/N611 glycan hole were primed, they showed limited neutralization breadth, and cryoEMPEM revealed key residue information to guide future vaccine design.
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Unlabelled: 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, placebo-controlled trial (HVTN 137A).

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Vaccination strategies against HIV-1 aim to elicit broadly neutralizing antibodies (bnAbs) using prime-boost regimens with HIV envelope (Env) immunogens. Early antibody responses to easily accessible epitopes on these antigens are directed to non-neutralizing epitopes instead of bnAb epitopes. Autologous neutralizing antibody responses appear upon boosting once immunodominant epitopes are saturated.

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A vaccine that can achieve protective immunity prior to sexual debut is critical to prevent the estimated 410,000 new HIV infections that occur yearly in adolescents. As children living with HIV can make broadly neutralizing antibody (bnAb) responses in plasma at a faster rate than adults, early childhood is an opportune window for implementation of a multi-dose HIV immunization strategy to elicit protective immunity prior to adolescence. Therefore, the goal of our study was to assess the ability of a B cell lineage-designed HIV envelope SOSIP to induce bnAbs in early life.

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Electron microscopy-based polyclonal epitope mapping (EMPEM) can delineate epitope specificities of serum antibodies to a given antigen following vaccination or infection. Here, we present a protocol for the EMPEM method for rapid high-throughput assessment of antibody responses to glycoprotein antigens in vaccination and infection studies. We describe steps for antibody isolation and digestion, antigen complex and purification, and electron microscope imaging.

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Understanding antibody-antigen interactions in a polyclonal immune response in humans and animal models is critical for rational vaccine design. Current approaches typically characterize antibodies that are functionally relevant or highly abundant. Here, we use photo-cross-linking and single-particle electron microscopy to increase antibody detection and unveil epitopes of low-affinity and low-abundance antibodies, leading to a broader structural characterization of polyclonal immune responses.

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Article Synopsis
  • Immunodominance of non-neutralizing antibodies and somatic hypermutation in germinal centers pose challenges for creating an effective HIV vaccine.
  • Researchers used implantable osmotic pumps to deliver targeted immunogens to rhesus macaques over six months, aiming to stimulate immune responses against a conserved fusion peptide.
  • Methods like electron microscopy polyclonal epitope mapping (EMPEM) and lymph node analysis tracked antibody responses, helping identify key residues for future vaccine design.
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Background: Older patients with advanced chronic kidney disease (CKD) face difficult decisions about managing kidney failure, frequently experiencing decisional conflict, regret, and treatment misaligned with preferences.

Objective: To assess whether a decision aid about kidney replacement therapy improved decisional quality compared with usual care.

Design: Multicenter, randomized, controlled trial.

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Article Synopsis
  • The study investigates the persistence of germinal centre B cells for over 6 months following HIV Env protein immunization in rhesus monkeys, showing a significant increase in B cells at week 10 compared to conventional methods.
  • Continuous somatic hypermutation of the B cells during the 29-week period indicates ongoing selection pressure, leading to a substantial boost in HIV-neutralizing antibodies after a single booster.
  • Findings suggest that a longer priming strategy can enhance immune memory, allowing B cells to better recognize challenging antigens, potentially improving vaccine efficacy for difficult targets.
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SIVmac239 infection of macaques is a favored model of human HIV infection. However, the SIVmac239 envelope (Env) trimer structure, glycan occupancy, and the targets and ability of neutralizing antibodies (nAbs) to protect against SIVmac239 remain unknown. Here, we report the isolation of SIVmac239 nAbs that recognize a glycan hole and the V1/V4 loop.

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Objectives: Patients with pelvic congestion syndrome (PCS) often report overlapping somatic symptoms and syndromes. The objective of this study was to explore the prevalence of co-existing symptoms and self-reported syndrome diagnoses among women with PCS and to inform future research hypotheses.

Methods: A brief online survey was offered to members of a PCS support group website.

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  • Scientists studied how people's previous infections with seasonal coronaviruses affect their response to SARS-CoV-2, the virus that causes COVID-19.
  • They used a special technique to look at how antibodies target different parts of the virus spikes.
  • The researchers found that most people had antibodies from earlier coronaviruses, which worked differently than those found in people who had recovered from COVID-19.
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One of the rate-limiting steps in analyzing immune responses to vaccines or infections is the isolation and characterization of monoclonal antibodies. Here, we present a hybrid structural and bioinformatic approach to directly assign the heavy and light chains, identify complementarity-determining regions, and discover sequences from cryoEM density maps of serum-derived polyclonal antibodies bound to an antigen. When combined with next-generation sequencing of immune repertoires, we were able to specifically identify clonal family members, synthesize the monoclonal antibodies, and confirm that they interact with the antigen in a manner equivalent to the corresponding polyclonal antibodies.

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Article Synopsis
  • This study investigates the immunogenicity of stabilized HIV vaccine candidates, specifically engineered ectodomain trimer immunogens based on the BG505 envelope glycoprotein, using rhesus macaques as subjects.
  • Researchers utilized a high-resolution imaging technique called cryoEMPEM to analyze the antibody responses generated from these vaccinations, highlighting its effectiveness without needing to isolate monoclonal antibodies.
  • The findings show that both engineered mutations and specific glycosylation sites on the immunogens can elicit immune responses, revealing important information about the types of epitopes that can be targeted for HIV vaccines.
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Evaluating the structure-function relationship of viral envelope (Env) evolution and the development of broadly cross-neutralizing antibodies (bnAbs) in natural infection can inform rational immunogen design. In the present study, we examined the magnitude and specificity of autologous neutralizing antibodies induced in rabbits by a novel HIV-1 clade C Env protein (1PGE-THIVC) vis-à-vis those developed in an elite neutralizer from whom the env sequence was obtained that was used to prepare the soluble Env protein. The novel 1PGE-THIVC Env trimer displayed a native like pre-fusion closed conformation in solution as determined by small angle X-ray scattering (SAXS) and negative stain electron microscopy (EM).

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Stabilized HIV-1 envelope (Env) trimers elicit tier 2 autologous neutralizing antibody (nAb) responses in immunized animals. We previously demonstrated that BG505 SOSIP.664.

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Porcine epidemic diarrhea virus (PEDV) is an alphacoronavirus responsible for significant morbidity and mortality in pigs. A key determinant of viral tropism and entry, the PEDV spike protein is a key target for the host antibody response and a good candidate for a protein-based vaccine immunogen. We used electron microscopy to evaluate the PEDV spike structure, as well as pig polyclonal antibody responses to viral infection.

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The induction of broad and potent immunity by vaccines is the key focus of research efforts aimed at protecting against HIV-1 infection. Soluble native-like HIV-1 envelope glycoproteins have shown promise as vaccine candidates as they can induce potent autologous neutralizing responses in rabbits and non-human primates. In this study, monoclonal antibodies were isolated and characterized from rhesus macaques immunized with the BG505 SOSIP.

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