Biology subjects

Mansur, D. S.

Publications and source records attributed to Mansur, D. S..

14 recordsLinked to original sources

bioRxiv2026

Genotype-Resolved Interaction Landscape of the Dengue Envelope Glycoprotein with Host Cellular Proteins: Structural Dynamics, Thermodynamic Cooperativity, and Binding Specificity

1Dengue virus (DENV) entry has historically been viewed as a receptor-centric process in which viral envelope proteins engage isolated host factors to initiate infection. However, mounting evidence reveals that viral attachment, internalization, and intracellular trafficking occur within complex molecular environments where multiple interacting host proteins shape the infection landscape. Here we introduce vectorial host interaction fields--a framework that represents intermolecular contacts as directional vectors embedded within host protein interaction networks, providing structural and systems-level insight into viral entry. Docking analyses were performed across sixteen dengue envelope genotype variants, whereas molecular dynamics and MM/GBSA analyses were conducted on representative complexes selected from this genotype-informed screening. We characterized dengue envelope interactions with thirteen host proteins involved in membrane attachment, receptor signaling, cytoskeletal transport, vesicular trafficking, proteostasis, and immune regulation. Our multiscale approach integrated protein-protein docking, 200 ns molecular dynamics simulations of representative complexes, MM/GBSA binding free energy analysis, and vectorial hydrogen-bond formalism encoding orientation, persistence, and angular entropy. We identified four recurrent viral interface architectures: multivalent anchoring (BiP/GRP78, Betaglycan), electrostatic sliding (Glypican-1), focal regulation (Claudin-1, SUMO), and conserved cytoskeletal modules (Actin, Rab5). Ternary docking analyses revealed that viral stability is strongly conditioned by local network context, with conditional {Delta}{Delta}G values ranging from approximately -3.4 to +6.9 kcal mol-1 depending on neighboring proteins and assembly sequence. These findings support a systems-level model of dengue entry driven by layered host interaction fields rather than a single dominant receptor, but they should be interpreted as computational structural hypotheses requiring biochemical, biophysical, and cellular validation. Detailed structural datasets, molecular dynamics trajectories, vectorial analyses, and per-residue MM/GBSA decomposition are provided in the companion Supplementary Material, which includes extended Results and Discussion, comprehensive Limitations assessment, and VectorPROT pipeline documentation supporting these findings.

biophysics↗

bioRxiv2025

IFIT3 controls IFIT1 accumulation and specificity preventing self mRNA targeting during the innate immune response.

IFIT1 is among the highest expressed proteins following virus detection and interferon (IFN) induction and binds the 5-end of non-self viral cap0-mRNAs lacking 2-O-methylation, blocking their translation. IFIT1 hetero-complexes with IFIT3, which enhances IFIT1 cap0-binding. Here, we demonstrate that IFIT3 is a master regulator of IFIT1, dictating its activity and stability. When expressed at high levels in the absence of IFIT3, IFIT1 can inhibit Semliki Forest virus replication, but can also inhibit translation of certain other self IFN-stimulated genes (ISGs), including the important innate immune proteins ISG15 and IFITM1 as exemplars. However, IFIT1:IFIT3 complexing rescues ISG15 and IFITM1 from IFIT1 translation inhibition. We demonstrate that IFIT1 is degraded by the proteasome in the absence of IFIT3, but that direct binding to IFIT3 protects IFIT1 from degradation, ensuring IFIT1 accumulation only occurs along with IFIT3, demonstrating a mechanism to control the fine balance between antiviral activity and self-targeting in the face of unrelenting viral evolution.

immunology↗

bioRxiv2025

Determinant host differences in ZIKV sfRNA accumulation.

Zika virus (Orthoflavivirus zikaese) is part of the Orthoflavivirus genus that contains several viral species posing major and expanding burdens to public health worldwide. Upon infection, orthoflaviviruses produce viral RNA fragments named sfRNAs (short flaviviral RNA), generated from viral genomic RNA incompletely degraded by Xrn1/Pcm, the major cellular 5-3 exonuclease. Several conserved elements in the orthoflavivirus 3 untranslated region (UTR) are responsible for XrnI-resistance, named xrRNA. The ubiquitous prevalence of xrRNA/sfRNA in flaviviruses indicate an important role of these structures in the viral life cycle, although their function is not completely understood. Here, we used in vitro reconstitution and infection models to examine the role of ZIKV xrRNA2 in mammalian and insect cells. SHAPE RNA structure probing revealed that disruption of ZIKV xrRNA2 does not affect xrRNA1 or dumbbell structure elsewhere in the 3UTR despite disrupting all sfRNA accumulation in mammalian cells. In vitro RNA degradation assays showed that xrRNA1 efficiently stalled human or mosquito Xrn1 independent of xrRNA2 integrity. Reversion in mammalian cells occurred at early passages in protein kinase R (PKR)-/- or IFN-receptor1 (IFAR1)-/-/PKR-/- knock out (KO) or double KO mammalian A549 cells, respectively, while wild-type virus outcompeted the xrRNA2 defective virus in RNAi-deficient mosquito cells. Together, our data reveals novel details of the mechanism of sfRNA accumulation in mammalian and insect cells We demonstrate a differential sensitivity to the absence of a functional xrRNA2 structure in mammalian and insect cells, with reversion to an active xrRNA2 occurring more rapidly in mammalian cells. Together, our work reveals new details on the requirements for ZIKV sfRNA accumulation in mammalian and mosquito cells.

microbiology↗

bioRxiv2025

A Specialized CD107a+ Macrophage Subset Drives Selective Mycobacterial Phagocytosis

Macrophages are essential for pathogen clearance, yet phagocytic specialization among subsets is poorly defined. Bone marrow-derived macrophages cultured with L929 supernatant or M-CSF separate into FSCloSSCloF4/80loCD11blo (FSCloSSClo) and FSChiSSChiF4/80hiCD11bhi (FSChiSSChi) subsets. Transcriptomic and functional analyses reveal that FSCloSSClo cells possess a hyperphagocytic program driven by enhanced actin cytoskeleton regulators (e.g., Arp2/3) and pro-inflammatory signaling (NF-{kappa}B). These cells excel at internalizing Mycobacterium tuberculosis virulent H37Rv and BCG through actin-mediated, cytochalasin D-sensitive mechanisms. High surface CD107a (LAMP1) expression marks this hyperphagocytic subset and correlates strongly with mycobacterial uptake. FSCloSSClo macrophages produce more TNF and IL-6 upon mycobacterial or TLR2/TLR5 stimulation yet retain IFN-{gamma}-mediated killing capacity. In vivo, CD107a alveolar macrophages in BCG-infected lungs preferentially capture bacilli and upregulate CD195, recapitulating the in vitro phenotype. These findings establish CD107a as a key surface marker of a hyperphagocytic macrophage subset and highlight its role in selective mycobacterial phagocytosis, providing new mechanistic understanding relevant to tuberculosis host defense and therapeutic development. HighlightsO_LIBone marrow-derived FSCloSSCloF4/80loCD11blo macrophage subset excels at M. tuberculosis and BCG uptake C_LIO_LIHyperphagocytic macrophages mount rapid pro-inflammatory TNF/IL-6 responses C_LIO_LICD107a (LAMP1) identifies a pre-existing hyperphagocytic macrophage subset in vitro and in vivo C_LIO_LIBCG infection triggers CD195 (CCR5) upregulation selectively on CD107a alveolar macrophages C_LI

immunology↗

bioRxiv2024

A Laboratory-Adapted and a Clinical Isolate of Dengue Virus Serotype 4 Differently Impact Aedes aegypti Life-History Traits Relevant to Vectorial Capacity

1Dengue virus cases are on the rise globally, and strategies to reduce new infections by controlling its primary vector, the mosquito Aedes aegypti, represent a promising biotechnological approach. However, the interaction between virus serotypes and genotypes with Aedes aegypti is poorly characterized at the molecular level, as well as in terms of life-history traits related to vector capacity and mosquito disease tolerance. Here, we infected Aedes aegypti with two philogenetically distant strains of Dengue virus serotype 4 genotype II: a laboratory-adapted strain, DENV4 - TVP/360, and a recent clinical strain isolated from southern Brazil, DENV4 - LRV 13/422. These strains, which exhibit 26 amino acid differences in their sequences, have been shown in to produce distinct immune phenotypes in vertebrate cells. Here, we assessed various life-history traits of Aedes aegypti, including mortality, fecundity, fertility, and induced flight capacity, as well as vector competence-related parameters such as infection intensity and prevalence, following exposure to different viral concentrations. We found that each viral strain differentially affected mosquito traits. While neither strain significantly reduced mosquito lifespan, Aedes aegypti infection prevalence was influenced by the initial dose of DENV4 - TVP/360. This laboratory-adapted strain also enhanced mosquito induced-flight capacity at early (24 hours post-infection - DPI) and late (21 DPI) time points. On the other hand, the recent clinical isolate, DENV4 - LRV 13/422, specifically reduced Aedes aegypti fertility. A better understanding of how different arbovirus strains influence mosquito life-history traits connected to disease spread will be critical in public health efforts to mitigate arbovirus outbreaks that are focused on the mosquito vector. 2 Highlights- The DENV4 strains TVP/360 and LRV 13/422 have 26 amino acid differences in their sequences. - Aedes aegypti infection prevalence is influenced by the initial dose of DENV4 - TVP/360 strain but not DENV4 - LRV 13/422. - Fertility is specifically reduced by DENV4 - LRV 13/422. - Induced-flight activity is enhanced at 1 and 21 days post-infection with DENV4 - TVP/360 strain.

microbiology↗

bioRxiv2022

Exploring dose-response relationships in Aedes aegypti survival upon bacteria and arbovirus infection.

A detailed understanding of host fitness changes upon variation in microbe density is a central aim of infection biology. Here, we applied dose-response curves to study Aedes aegypti survival upon exposure to different microbes. We challenged female mosquitoes with Listeria monocytogenes, a model bacterial pathogen, Dengue 4 virus and Zika virus, two medically relevant arboviruses, to understand the distribution of mosquito susceptibility and net fitness (survival) following microbe exposure. By correlating microbe loads and host health, we found that a blood meal promotes survival in our systemic bacterial infection model and that mosquitoes orally infected with bacteria had an enhanced defensive capacity than insects infected through injection. We also showed that Aedes aegypti has a higher survival profile upon arbovirus infection but, under the conditions tested, was more susceptible to Zika virus when compared to Dengue virus. Here, we applied a framework for the study of microbe-induced mosquito mortality detailing how Aedes aegypti lifespan varies upon different inoculum sizes of bacteria and arboviruses.

microbiology↗

bioRxiv2022

LUBAC is required for RIG-I sensing of RNA viruses

The ability of cells to mount an interferon response to virus infections depends on intracellular nucleic acid sensing pattern recognition receptors (PRRs). RIG-I is an intracellular PRR that binds short double stranded viral RNAs to trigger MAVS-dependent signalling. The RIG-I/MAVS signalling complex requires the coordinated activity of multiple kinases and E3 ubiquitin ligases to activate the transcription factors that drive type I and type III interferon production from infected cells. The linear ubiquitin chain assembly complex (LUBAC) regulates the activity of multiple receptor signalling pathways in both ligase-dependent and -independent ways. Here, we show that the three proteins that constitute LUBAC have separate functions in regulating RIG-I signalling. Both HOIP, the E3 ligase capable of generating M1-ubiquitin chains, and LUBAC accessory protein HOIL-1 are required for viral RNA sensing by RIG-I. The third LUBAC component, SHARPIN, is not required for RIG-I signalling. These data cement the role of LUBAC as a positive regulator of RIG-I signalling and as an important component of antiviral innate immune responses.

immunology↗

bioRxiv2021

PKR-MEDIATED STRESS RESPONSE ENHANCES DENGUE AND ZIKA VIRUS REPLICATION

The mechanisms by which flaviviruses use non-canonical translation to support their replication in host cells are largely unknown. Here we investigated how the integrated stress response (ISR), which promotes translational arrest by eIF2[a] phosphorylation (p-eIF2[a]), regulates flavivirus replication. During Dengue virus (DENV) and Zika virus (ZIKV) infection, eIF2[a] phosphorylation peaked at 24 hours post infection and was dependent on PKR but not type I interferon. The ISR is activated downstream of p-eIF2 during infection with either virus, but translation arrest only occurred following DENV4 infection. Despite this difference, both DENV4 and ZIKV replication was impaired in cells lacking PKR, independent of IFN-I/NF-kB signalling or cell viability. By using a ZIKV 5' UTR reporter system as a model, we found that this region of the genome is sufficient to promote an enhancement of viral mRNA translation in the presence of an active ISR. Together we provide evidence that flaviviruses escape ISR translational arrest and co-opt this response to increase viral replication.

immunology↗

bioRxiv2020

Neuraminidase inhibitors rewire neutrophil function in murine sepsis and COVID-19 patient cells

Neutrophil overstimulation plays a crucial role in tissue damage during severe infections. Neuraminidase (NEU)-mediated cleavage of surface sialic acid has been demonstrated to regulate leukocyte responses. Here, we report that antiviral NEU inhibitors constrain host NEU activity, surface sialic acid release, ROS production, and NETs released by microbial-activated human neutrophils. In vivo, treatment with Oseltamivir results in infection control and host survival in peritonitis and pneumonia models of sepsis. Single-cell RNA sequencing re-analysis of publicly data sets of respiratory tract samples from critical COVID-19 patients revealed an overexpression of NEU1 in infiltrated neutrophils. Moreover, Oseltamivir or Zanamivir treatment of whole blood cells from severe COVID-19 patients reduces host NEU-mediated shedding of cell surface sialic acid and neutrophil overactivation. These findings suggest that neuraminidase inhibitors can serve as host-directed interventions to dampen neutrophil dysfunction in severe infections. At a GlanceIn a severe systemic inflammatory response, such as sepsis and COVID-19, neutrophils play a central role in organ damage. Thus, finding new ways to inhibit the exacerbated response of these cells is greatly needed. Here, we demonstrate that in vitro treatment of whole blood with the viral neuraminidase inhibitors Oseltamivir or Zanamivir, inhibits the activity of human neuraminidases as well as the exacerbated response of neutrophils. In experimental models of severe sepsis, oseltamivir decreased neutrophil activation and increased the survival rate of mice. Moreover, Oseltamivir or Zanamivir ex vivo treatment of whole blood cells from severe COVID-19 patients rewire neutrophil function.

immunology↗

bioRxiv2019

Flaviviruses exploit fine-tuning of the interferon response to promote replication

The establishment of a virus infection is the result of the pathogens ability to replicate in a hostile environment generated by the hosts immune system. Here, we found that ISG15 restricts Dengue and Zika viruses replication through the stabilisation of its binding partner USP18. ISG15 expression was necessary to control DV replication driven by both autocrine and paracrine type one interferon (IFN-I) signalling. Moreover, USP18 competes with NS5-mediated STAT2 degradation, a major mechanism for establishment of flavivirus infection. Strikingly, reconstitution of USP18 in ISG15-deficient cells was sufficient to restore the STAT2s stability and restrict virus growth, suggesting that the IFNAR-mediated ISG15 activity is also antiviral. Our results add a novel layer of complexity in the virus/host interaction interface and suggest that NS5 has a narrow window of opportunity to degrade STAT2, therefore suppressing hosts IFN-I mediated response and promoting virus replication. IMPORTANCEDisease is an emergent property that results from a microorganisms ability to replicate in a given host and the latters immune response. Here we describe how the immunoregulatory function of ISG15 (an interferon stimulated gene) affects Dengue and Zika virus replication by occupying a niche used by the virus non-structural protein 5 (NS5) to evade hosts immunity. In the absence of ISG15, NS5 efficiently degrades a main signalling hub of innate immunity (STAT2), leading to cell immune suppression and consequently virus growth. This sheds light into how flaviviruses intimately interact with the host immune system and could lead to a host-based therapy target.

immunology↗

bioRxiv2019

Mycobacterium tuberculosis hijacks an evolutionary recent IFN-IL-6-CEBP axis linked to monocyte development and disease severity in humans

Monocyte counts are increased during human tuberculosis (TB) but it has not been determined whether Mycobacterium tuberculosis (Mtb) directly regulates myeloid commitment. We demonstrated that exposure to Mtb directs primary human CD34+ cells to differentiate into monocytes/macrophages. In vitro myeloid conversion did not require type I or type II IFN signaling. In contrast, Mtb enhanced IL-6 responses by CD34+ cell cultures and IL-6R neutralization inhibited myeloid differentiation and decreased mycobacterial growth in vitro. Integrated systems biology analysis of transcriptomic, proteomic and genomic data of large data sets of healthy controls and TB patients established the existence of a myeloid IL-6/IL6R/CEBP gene module associated with disease severity. Furthermore, genetic and functional analysis revealed the IL6/IL6R/CEBP gene module has undergone recent evolutionary selection, including Neanderthal introgression and human pathogen adaptation, connected to systemic monocyte counts. These results suggest Mtb co-opts an evolutionary recent IFN-IL6-CEBP feed-forward loop, increasing myeloid differentiation linked to severe TB in humans.

immunology↗

bioRxiv2018

Vasculature-associated adipose tissue macrophages dynamically adapt to inflammatory and metabolic challenges

Tissue-resident macrophages comprise the most abundant immune cell population in healthy adipose tissue. Adipose tissue macrophage populations change during metabolic stress and ageing, and are thought to contribute to the pathogenesis of obesity. Here, we studied adipose tissue macrophage subpopulations in the steady state, and in response to nutritional and infectious challenges.\n\nUsing comprehensive cell-surface-based and gene expression analyses, we found that tissue-resident macrophages from healthy epididymal white adipose tissue (eWAT) tightly associate with blood vessels, displaying a very high endocytic capacity. We refer to these cells as Vasculature-associated Adipose tissue Macrophages (VAMs). Chronic high fat diet (HFD) feeding results in the accumulation of a monocyte-derived CD11c+CD64+ double positive (DP) macrophage eWAT population with a predominant anti-inflammatory gene profile, but reduced endocytic function. In contrast, fasting rapidly and reversibly leads to VAM depletion, while acute inflammatory stress induced by pathogens transiently depletes VAMs and simultaneously boosts DP macrophage accumulation. Our results indicate that adipose tissue macrophage populations adapt to metabolic stress and inflammation, suggesting an important role for these cells in restoring homeostasis.

immunology↗

bioRxiv2018

IFIT3 and IFIT2/3 promote IFIT1-mediated translation inhibition by enhancing binding to non-self RNA.

Interferon-induced proteins with tetratricopeptide repeats (IFITs) are highly expressed during the cell-intrinsic immune response to viral infection. IFIT1 inhibits translation by binding directly to the 5' end of foreign RNAs, particularly those with non-self cap structures, precluding the recruitment of the cap-binding eukaryotic translation initiation factor 4F and subsequent 40S recruitment. Interaction of different IFIT family members is well described, but little is known of the molecular basis of IFIT association or its impact on function. Here, we reconstituted different complexes of IFIT1, IFIT2 and IFIT3 in vitro, which enabled us to reveal critical aspects of IFIT complex assembly. IFIT1 interacts rapidly and strongly with IFIT3 forming a stable heterotetramer. IFIT2 and IFIT3 homodimers dissociate to form a more stable heterodimer that associates with IFIT1, forming an IFIT1:IFIT2:IFIT3 trimer. Site-directed mutagenesis revealed a C-terminal YxxxL motif in IFIT1 that mediates its association with IFIT3. Using various reporter mRNAs, we demonstrate for the first time that IFIT3 stabilises IFIT1 binding to cap0-mRNA and enhances its translation inhibition activity. Disrupting the binding interface between IFIT1 and IFIT3 abrogated this enhancement. This work reveals molecular aspects of IFIT assembly and provides an important missing link between IFIT interaction and function.

immunology↗

bioRxiv2017

ISG15 induces IL-10 production in human monocytes and is a biomarker of disease severity during active tuberculosis

Interferon stimulated gene 15 (ISG15) deficiency in humans leads to severe interferonopathies and mycobacterial disease, the latter being previously associated to its extracellular cytokine-like activity. Here, we demonstrate a novel role for secreted ISG15 as an IL-10 inducer, unique to human primary monocytes. Employing ex vivo systems analysis of human transcriptome datasets, we observed a significant correlation of ISG15-induced monocyte IL-10 and lymphocyte IFN{gamma} balanced expression. This effect was associated with p38 MAPK and PI3K signalling in healthy volunteers. The specificity and MAPK/PI3K-dependence of ISG15-induced monocyte IL-10 production was confirmed in vitro using CRISPR/Cas9 knockout and pharmacological inhibitors. Moreover, this ISG15/IL10 axis was amplified in leprosy but disrupted in human active tuberculosis (TB) patients. Importantly, ISG15 strongly correlated with inflammation and disease severity during active TB. In conclusion, this study identifies a novel anti-inflammatory ISG15/IL-10 myeloid axis that is disrupted in active TB, revealing a potential biomarker for disease severity in this major human disease.

immunology↗