Biology subjects

Guerra, D.

Publications and source records attributed to Guerra, D..

9 recordsLinked to original sources

bioRxiv2026

Phenuivirus glycoprotein Gc domain is a conserved target of cross-functional monoclonal antibodies

Phenuiviruses which include Rift Valley Fever Virus (RVFV), classified by WHO as one of the top priority pathogens with outbreak potential, are emerging arthropod-borne viruses that pose an increasing threat to public health. In line with the prototype pathogen framework advanced by the NIAID, the sandfly-transmitted Toscana virus (TOSV) has been adopted as a prototype to advance understanding of relevant phenuiviruses and inform the development of broadly applicable medical countermeasures. In this study, we sought to isolate and characterize monoclonal antibodies (mAbs) elicited by natural TOSV infection to identify shared antigenic determinants. By employing the conserved envelope Gc glycoprotein as bait for antigen-specific B cell sorting, we recovered more than 1,450 memory B cells and identified 112 Gc-specific neutralizing mAbs. Over one-third of these mAbs exhibited cross-reactivity with RVFV, a genetically distinct phenuivirus. Selected mAbs provided prophylactic protection in a murine model of TOSV infection. Together, our findings establish Gc as an important target of protective neutralizing antibodies and provide insights that may guide the rational design of widely effective interventions, strengthening readiness against future phenuivirus outbreaks.

immunology↗

bioRxiv2025

Multimodal single-cell analysis following SARS-CoV-2 breakthrough infection reveals distinct B cell populations

B cells underpin durable immunity by generating long-lived memory B cells and antibody-secreting cells (ASCs) that re-engage upon antigen re-encounter. How human IgG memory B cells are organized to establish, maintain, and reactivate humoral immunity remains incompletely understood. Here, we combine multimodal single-cell profiling with longitudinal characterization of antigen-specific memory B cells following SARS-CoV-2 infection and vaccination to define the developmental relationships and biological functions of human IgG memory B cell subsets. We identify a coordinated activation-memory cycle shared by germinal center- and extrafollicular-derived memory B cells marked by differential CD45RB expression. Within this cycle, activated B cells represent specialized effector cells that acquire inflammatory responsiveness, migratory capacity, and differentiation potential toward ASCs. Activated memory B cells persist as an intermediate that retains migratory capacity while shifting toward homeostatic survival, preserving recall competence and contributing to the regeneration of long-lived resting memory. The resting memory compartment comprises two complementary populations: CD73 resting memory B cells form the principal long-lived recall reservoir, whereas CD24 resting memory B cells adopt a more regulatory resting state and shows limited participation in the SARS-CoV-2 recall response. We further identify a CD24 intermediate population as the earliest transitional state emerging upon memory B cell reactivation, bridging resting memory and the effector recall response. Together, these findings establish the human IgG memory B cell compartment as a dynamic activation-memory cycle rather than a collection of static subsets, providing a framework for understanding humoral immunity and interpreting B cell responses in vaccination, infection, and immune-mediated disease. One sentence summaryOur results provide novel insights on B cell recall responses after SARS-CoV-2 infection or vaccination, formulating distinct classical and non-classical re-activation trajectories from a resting memory state through intermediate phenotypes towards an activated state.

immunology↗

bioRxiv2024

An operational framework to map Essential Life Support Areas (ELSAs) for biodiversity, climate, and sustainable development

Almost all countries are making increasingly bold commitments to halt and reverse biodiversity loss, minimise the impacts of climate change, and transition to more sustainable development. The effective achievement of many of these commitments relies on integrated spatial planning frameworks that are adaptable to national circumstances, priorities and capabilities. This need is formally recognized by Target 1 of the Kunming-Montreal Global Biodiversity Framework (GBF), which specifies that all areas should be under such planning. Here, we describe the development and application of an operational framework for national-level integrated spatial planning: Essential Life Support Areas (ELSAs). This framework facilitates the identification of areas that - if protected, restored, or sustainably managed - can support the achievement of national commitments to biodiversity, climate, and sustainable development. The process of mapping ELSAs relies heavily on leadership by national experts and stakeholders and the integration of spatial data using systematic conservation planning tools. We showcase the ELSA process carried out for Ecuador, where the use of real-time scenario analyses enabled diverse stakeholder groups to collaborate to assess national priorities for nature, climate, and sustainable development, view trade-offs and synergies, and arrive at a spatial plan to guide national action. ELSA presented an actionable approach for Ecuador, and 12 other pilot countries, to create a spatial plan aimed at fulfilling their national and international commitments to nature, including to the GBF.

ecology↗

bioRxiv2024

Broadening sarbecovirus neutralization with bispecific antibodies combining distinct conserved targets on the receptor binding domain

Monoclonal neutralizing antibodies (mAbs) are considered an important prophylactic against SARS-CoV-2 infection in at-risk populations and a strategy to counteract future sarbecovirus-induced disease. However, most mAbs isolated so far neutralize only a few sarbecovirus strains. Therefore, there is a growing interest in bispecific antibodies (bsAbs) which can simultaneously target different spike epitopes and thereby increase neutralizing breadth and prevent viral escape. Here, we generate and characterize a panel of 30 novel broadly reactive bsAbs using an efficient controlled Fab-arm exchange protocol. We specifically combine some of the broadest mAbs described so far, which target conserved epitopes on the receptor binding domain (RBD). Several bsAbs show superior cross-binding and neutralization compared to the parental mAbs against sarbecoviruses from diverse clades, including recent SARS-CoV-2 variants. BsAbs which include mAb COVA2-02 are among the most potent and broad combinations. As a result, we study the unknown epitope of COVA2-02 and show that this mAb targets a distinct conserved region at the base of the RBD, which could be of interest when designing next-generation bsAb constructs to contribute to a better pandemic preparedness.

microbiology↗

bioRxiv2022

Identification of new drugs to counteract anti-spike IgG-induced hyperinflammation in severe COVID-19

Previously, we and others have shown that SARS-CoV-2 spike-specific IgG antibodies play a major role in disease severity in COVID-19 by triggering macrophage hyperactivation, disrupting endothelial barrier integrity, and inducing thrombus formation. This hyper-inflammation is dependent on high levels of anti-spike IgG with aberrant Fc tail glycosylation, leading to Fc{gamma} receptor hyper-activation. For development of immune-regulatory therapeutics, drug specificity is crucial to counteract excessive inflammation while simultaneously minimizing inhibition of antiviral immunity. We here developed an in vitro activation assay to screen for small molecule drugs that specifically counteract antibody-induced pathology. We identified that anti-spike induced inflammation is specifically blocked by small molecule inhibitors against SYK and PI3K. We identified SYK inhibitor entospletinib as the most promising candidate drug, which also counteracted anti-spike-induced endothelial dysfunction and thrombus formation. Moreover, entospletinib blocked inflammation by different SARS-CoV-2 variants of concern. Combined, these data identify entospletinib as a promising treatment for severe COVID-19. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=136 SRC="FIGDIR/small/521247v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@edb3d5org.highwire.dtl.DTLVardef@1b99dd8org.highwire.dtl.DTLVardef@129ec7corg.highwire.dtl.DTLVardef@165000f_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2022

Broad SARS-CoV-2 Neutralization by Monoclonal and Bispecific Antibodies Derived from a Gamma-infected Individual

The worldwide pandemic caused by SARS-CoV-2 has remained a human medical threat due to the continued evolution of multiple variants that acquire resistance to vaccines and prior infection. Therefore, it is imperative to discover monoclonal antibodies (mAbs) that neutralize a broad range of SARS-CoV-2 variants for therapeutic and prophylactic use. A stabilized autologous SARS-CoV-2 spike glycoprotein was used to enrich antigen-specific B cells from an individual with a primary Gamma variant infection. Five mAbs selected from those B cells showed considerable neutralizing potency against multiple variants of concern, with COVA309-35 being the most potent against the autologous virus, as well as against Omicron BA.1 and BA.2. When combining the COVA309 mAbs as cocktails or bispecific antibody formats, the breadth and potency was significantly improved against all tested variants. In addition, the mechanism of cross-neutralization of the COVA309 mAbs was elucidated by structural analysis. Altogether these data indicate that a Gamma-infected individual can develop broadly neutralizing antibodies.

immunology↗

bioRxiv2021

A public antibody class recognizes a novel S2 epitope exposed on open conformations of SARS-CoV-2 spike

Delineating the origins and properties of antibodies elicited by SARS-CoV-2 infection and vaccination is critical for understanding their benefits and potential shortcomings. Therefore, we investigated the SARS-CoV-2 spike (S)-reactive B cell repertoire in unexposed individuals by flow cytometry and single-cell sequencing. We found that [~]82% of SARS-CoV-2 S-reactive B cells show a naive phenotype, which represents an unusually high fraction of total human naive B cells ([~]0.1%). Approximately 10% of these naive S-reactive B cells shared an IGHV1-69/IGKV3-11 B cell receptor pairing, an enrichment of 18-fold compared to the complete naive repertoire. A proportion of memory B cells, comprising switched ([~]0.05%) and unswitched B cells ([~]0.04%), was also reactive with S and some of these cells were reactive with ADAMTS13, which is associated with thrombotic thrombocytopenia. Following SARS-CoV-2 infection, we report an average 37-fold enrichment of IGHV1-69/IGKV3-11 B cell receptor pairing in the S-reactive memory B cells compared to the unselected memory repertoire. This class of B cells targets a previously undefined non-neutralizing epitope on the S2 subunit that becomes exposed on S proteins used in approved vaccines when they transition away from the native pre-fusion state because of instability. These findings can help guide the improvement of SARS-CoV-2 vaccines.

immunology↗

bioRxiv2020

Potent neutralizing antibodies from COVID-19 patients define multiple targets of vulnerability

The rapid spread of SARS-CoV-2 has a significant impact on global health, travel and economy. Therefore, preventative and therapeutic measures are urgently needed. Here, we isolated neutralizing antibodies from convalescent COVID-19 patients using a SARS-CoV-2 stabilized prefusion spike protein. Several of these antibodies were able to potently inhibit live SARS-CoV-2 infection at concentrations as low as 0.007 {micro}g/mL, making them the most potent human SARS-CoV-2 antibodies described to date. Mapping studies revealed that the SARS-CoV-2 spike protein contained multiple distinct antigenic sites, including several receptor-binding domain (RBD) epitopes as well as previously undefined non-RBD epitopes. In addition to providing guidance for vaccine design, these mAbs are promising candidates for treatment and prevention of COVID-19.

microbiology↗

bioRxiv2018

Hybrid de novo assembly of the draft genome of the freshwater mussel Venustaconcha ellipsiformis (Bivalvia: Unionida).

Freshwater mussels (Bivalvia: Unionida) serve an important role as aquatic ecosystem engineers but are one of the most critically imperilled groups of animals. Here, we used a combination of sequencing strategies to assemble and annotate a draft genome of Venustaconcha ellipsiformis, which will serve as a valuable genomic resource given the ecological value and unique \"doubly uniparental inheritance\" mode of mitochondrial DNA transmission of freshwater mussels. The genome described here was obtained by combining high coverage short reads (65X genome coverage of Illumina paired-end and 11X genome coverage of mate-pairs sequences) with low coverage Pacific Biosciences long reads (0.3X genome coverage). Briefly, the final scaffold assembly accounted for a total size of 1.54Gb (366,926 scaffolds, N50 = 6.5Kb, with 2.3% of \"N\" nucleotides), representing 86% of the predicted genome size of 1.80Gb, while over one third of the genome (37.5%) consisted of repeated elements and more than 85% of the core eukaryotic genes were recovered. Given the repeated genetic bottlenecks of V. ellipsiformis populations as a result of glaciations events, heterozygosity was also found to be remarkably low (0.6%), in contrast to most other sequenced bivalve species. Finally, we reassembled the full mitochondrial genome and found six polymorphic sites with respect to the previously published reference. This resource opens the way to comparative genomics studies to identify genes related to the unique adaptations of freshwater mussels and their distinctive mitochondrial inheritance mechanism.

genomics↗