Search Results (756)

NS4A plays a role in forming the flavivirus replication complex, which inhibits apoptosis in host cells by inducing autophagy, thereby promoting viral replication. The host protein ENO1 interacts with NS4A, but the precise mechanism underlying this interaction and its role in viral replication remain unclear. In this study, we identified ZIKV NS4A^1–73 as a key regulator of replication and infection cycles in both temporal and spatial dimensions. Through surface plasmon resonance (SPR) analysis, we demonstrated that ENO1 directly interacts with NS4A^1–73. This critical binding inhibits the enzymatic activity of ENO1 and reduces cellular lactate and ATP production. Our findings suggest that ZIKV NS4A may effectively impede cellular metabolism by targeting the host factor ENO1, thus disrupting the glycolytic process. This insight could open new avenues for targeting ZIKV and similar viruses in therapeutic strategies. Full article

Zika virus (ZIKV) remains a significant global public health threat due to its association with severe neurological and ocular abnormalities, including microcephaly and congenital glaucoma in infants. Viruses often exploit host metabolic programs, such as energy and lipid metabolism, to support their replication. However, how ZIKV-driven metabolic reprogramming affects the anterior segment of the eye, especially trabecular meshwork (TM) cells, remains poorly defined. In this study, we investigated the roles of AMP-activated protein kinase (AMPK) signaling, fatty acid (FA) metabolism, and lipid droplet (LD) biogenesis in ZIKV-induced ocular pathogenesis using primary human TM cells and an IFNAR1-deficient mouse model. ZIKV infection triggered time-dependent activation of the LKB1-AMPK-ACC signaling axis and significantly increased LD accumulation. Pharmacological activation of AMPK suppressed viral replication, whereas its inhibition enhanced infection, highlighting an antiviral role for AMPK signaling. In contrast, ZIKV promoted LD biogenesis, and inhibition of DGAT1 reduced both LD formation and viral replication, indicating a proviral role for LDs. Modulation of FA metabolism further revealed differential effects on ZIKV infection: saturated FA (palmitate) enhanced viral replication, whereas inhibition of FA oxidation with etomoxir reduced infection. Conversely, unsaturated FAs (oleate and linoleate) suppressed viral replication, in part by impairing viral binding and entry. Collectively, these findings show that ZIKV reshapes host metabolic pathways in TM by differentially engaging AMPK signaling, FA metabolism, and LD biogenesis to promote viral replication and spread in ocular tissue. Targeting these metabolic pathways may offer promising therapeutic avenues for preventing and/or treating ZIKV-associated ocular complications. Full article

Endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) represent fundamental cellular adaptive mechanisms that maintain protein homeostasis and metabolic balance. Many RNA viruses, particularly flaviviruses such as dengue virus (DENV), Zika virus (ZIKV), West Nile virus (WNV), yellow fever virus (YFV), and Japanese encephalitis virus (JEV), extensively remodel the ER to establish replication compartments and assemble progeny virions. This massive reorganization disrupts ER homeostasis, leading to UPR activation. Emerging evidence reveals that flaviviruses not only trigger but also manipulate the three UPR branches—PERK, IRE1, and ATF6—to optimize viral translation, replication, and egress. In parallel, flavivirus infection profoundly alters host lipid metabolism and promotes dynamic changes in lipid droplets (LDs), key organelles that mediate lipid storage and serve as scaffolds for viral replication and assembly. The UPR intimately connects to LD biogenesis through transcriptional and translational programs mediated by XBP1, ATF4, and ATF6, thereby coupling ER stress responses to lipid remodeling and energy homeostasis. This intricate crosstalk between UPR and LDs creates a metabolic and structural niche favorable for viral replication but detrimental to host cell integrity. This review provides a comprehensive analysis of the molecular mechanisms by which flaviviruses exploit ER stress and the UPR to reprogram lipid metabolism and LD dynamics. We highlight the dual role of UPR signaling in promoting adaptive lipid synthesis and initiating cell death under prolonged stress, discuss recent insights into ER–LD interactions during flavivirus infection, and explore therapeutic opportunities targeting UPR–lipid metabolic pathways as broad-spectrum antiviral strategies. Understanding this interconnected network will advance our knowledge of viral pathogenesis and identify new avenues for host-directed antiviral intervention. Full article

Background/Objectives: Febrile illness in returning travelers presents a diagnostic and operational challenge for emergency medicine clinicians as early symptoms of high-consequence tropical infections often overlap with common viral syndromes. This review synthesizes current evidence to guide frontline clinicians in the systematic evaluation, diagnosis, and management of internally acquired febrile illnesses with a focus on pathogen of greatest relevance to United States (US) emergency departments (ED). Methods: We conducted a narrative review of the literature addressing epidemiology, clinical presentation, diagnostic testing, and management strategies for key travel-associated infections. Special consideration was given to rapid diagnostic modalities, pediatric risk factors, and infections most frequently implicated in returning travelers, including chikungunya (CHIK), dengue virus (DENV) disease, Ebola virus (EBV) disease, malaria, Mpox, typhoid fever (TF), yellow fever (YF), and Zika virus (ZIKV) disease. Results: Effective evaluation begins with a detailed travel and exposure history, recognition of epidemiologic and clinical red flags, and targeted use of rapid diagnostic tests. Malaria remains the most common life-threatening cause of post-travel fever and the only pathogen with reliable Food and Drug Administration (FDA)-cleared rapid testing available in the ED. Arboviral infections such as DENV, CHIK, ZIKV, and YFrequire region-specific consideration and phase-appropriate molecular or serologic evaluation. Emerging and high-consequence pathogens, including Mpox and EBV, necessitate strict infection control measures and coordination with public health authorities. Pediatric travelers, particularly those visiting friends and relatives, face disproportionate risk for severe systemic infections and often require broader diagnostic testing. Conclusions: A structured approach integrating travel history, focused examination, rapid diagnostics, and early recognition of high-risk features is essential to improving outcomes for febrile returning travelers. Strengthened vector control, enhanced vaccination uptake, and global surveillance are critical to reducing future disease burden. Full article

Background: Despite significant improvements in blood safety, the risk of transfusion-transmitted infections persists, particularly from emerging and re-emerging viruses. For red blood cell (RBC) products, this risk is exacerbated by the fact that there is no routine testing for many of these pathogens, and effective, commercially available pathogen inactivation technologies specifically for RBCs are still lacking. This gap in the safety framework means that viruses capable of establishing an asymptomatic viremia—a characteristic of many arboviruses like Zika, dengue, and West Nile virus—present a tangible threat to the blood supply, highlighting the need for broad-spectrum countermeasures. Study Design and Methods: This study aims to investigate the antiviral activity of green tea extract (GTE) and its key catechins, epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), against ZIKV in both cellular models and red blood cell (RBC) products. In vitro antiviral activity was assessed using A549 cells treated with GTE (150 μg/mL) or purified EGCG/ECG (20 μM). Mechanistic studies focused on viral attachment inhibition. Additionally, ZIKV-spiked RBC products were co-incubated with GTE (300 μg/mL) for 1 h to evaluate virucidal effects. Erythrocyte integrity was confirmed via hemolysis assays. Results: Co-treatment with GTE or catechins suppressed ZIKV replication by ≥3.64 logs (p < 0.001) in A549 cells. GTE and catechins primarily inhibited viral attachment. In RBCs, GTE reduced viral infectivity by 99.99% (4-log reduction) without compromising erythrocyte membrane integrity or cellular viability. Furthermore, RBCs with added GTE demonstrated a lower hemolysis rate during storage for up to 60 days. Conclusions: GTE exhibits potent virucidal activity against ZIKV in blood matrices, highlighting its potential as a pathogen reduction agent to enhance transfusion safety. Further development of GTE-based additive solutions or technologies is warranted. Full article

The overuse of chemical insecticides highlights the urgent need for novel vector control strategies. Insect-specific viruses (ISVs), such as the cell-fusing agent virus (CFAV), have shown potential to block arbovirus transmission by inhibiting viral replication in mosquitoes. However, the effects of CFAV beyond its natural host, Aedes aegypti, remain largely unexplored. In this study, we established a CFAV infection model in Aedes albopictus, a major vector for Zika virus (ZIKV), via intrathoracic injection. Stable infection was achieved, with viral loads reaching up to 10⁷ copies per mosquito by day 10 post-injection. Nevertheless, high post-injection mortality (median survival: 3 days) was observed, which we attribute primarily to mechanical injury. No evidence of vertical transmission of CFAV was detected in Ae. albopictus. Co-injection of CFAV and ZIKV did not significantly affect ZIKV replication in this species. In contrast, in Ae. aegypti pre-infected with CFAV followed by oral ZIKV challenge, CFAV significantly reduced ZIKV infection rates in the ovaries at day 4 and viral loads in salivary glands at day 10. These findings demonstrate that while CFAV can productively infect Ae. albopictus, it does not undergo vertical transmission in this species, and has no inhibitory effect on ZIKV under the co-infection conditions tested. This study underscores challenges associated with using single ISVs such as CFAV for arbovirus control and highlights the complex, bidirectional role of multiple ISV co-infections. While exploring multi-ISV combinations may offer a potential strategy to enhance antiviral efficacy, their net effect—whether suppression or enhancement of arboviruses—warrants careful investigation. Full article

Background: Zika virus (ZIKV) is a mosquito-borne flavivirus associated with severe neurological disease, including congenital Zika syndrome (CZS) following utero infection and Guillain–Barré syndrome in adults. The 2015–2016 epidemic in the Americas highlighted the profound maternal and neonatal consequences of ZIKV infection. Although reported transmission has declined, ongoing circulation of competent vectors and population susceptibility sustain a substantial risk of future outbreaks, underscoring the need for effective vaccines. Methods: We developed a recombinant Modified Vaccinia Ankara (MVA)-based vaccine candidate expressing the ZIKV pre-membrane (prM) and envelope (E) proteins and evaluated its immunogenicity and protective efficacy in interferon receptor-deficient AG129 mice. Results: Vaccination induced strong humoral and cellular immune responses and conferred significant protection against viral replication in key target organs, including the brain and testes, following ZIKV challenge. Conclusions: These preclinical findings support further development of this MVA-based ZIKV vaccine as a promising strategy to prevent ZIKV infection and its associated neurological complications. Full article

Zika virus (ZIKV), a unique flavivirus with neurotropic and teratogenic potential, can cross the blood–brain barrier and persist in human brain microvascular endothelial cells (BMECs); however, no approved vaccines or specific antivirals exist, and its barrier-crossing and neuroinvasive mechanisms remain elusive. Innovative strategies to identify additional host factors mediating ZIKV infection could yield key insights and help address these challenges. To uncover novel host factors, we established the first tree shrew (Tupaia belangeri) genome-wide CRISPR/Cas9 knockout (GeCKO) library and performed a screen in BMECs, identifying ring finger protein 6 (RNF6) as a novel proviral factor for ZIKV. ZIKV infection in BMECs was significantly reduced following RNF6 knockout or knockdown but enhanced upon RNF6 overexpression or rescue. Mechanistically, RNF6 interacts with the ZIKV NS5 protein and acts as a potential negative regulator of the type I interferon and MAPK signaling pathways. Evolutionary and structural analyses revealed that RNF6 is highly conserved between humans and tree shrews; molecular docking further identified shared NS5-binding residues (Gln-59, Arg-140), supporting the conserved proviral role of human RNF6 in ZIKV infection. Our findings highlight tree shrew GeCKO screening as an efficient approach for identifying novel host factors and establish RNF6 as a critical proviral factor for ZIKV replication in BMECs, providing new insights into ZIKV neurotropic pathogenesis and informing potential antiviral strategies. Full article

A small library of 23 pyrrole-based tricyclic derivatives bearing bulky amine moieties was synthesized, and all were evaluated for their antiviral activities against ZIKV and SARS-CoV. Three compounds, derivatives 2g, 2h and 2j, elicited interesting activity against ZIKV: compound 2g, containing a bornylamine residue, showed the best activity against Huh-7 cells with EC₅₀ and CC₅₀ values of 0.4 μM and 230.5 μM, respectively, and a Selectivity Index (SI) of 501. All three compounds reduce ZIKV yield primarily by impairing viral protein. Full article

The endo-lysosomal channel TRPML2 regulates key processes like membrane trafficking and autophagy, which are hijacked by many RNA viruses during endocytic entry. However, the development of TRPML2-targeted therapeutics has been hindered by a notable lack of high-affinity and selective peptide-based activators. Scorpion venom peptides, honed by evolution for exceptional specificity toward diverse membrane ion channels, represent a promising, underexplored natural library for discovering novel pharmacological probes and drug leads. Here, we screened and identified seven candidate peptides interacting with TRPML2 using co-immunoprecipitation combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of the Mesobuthus martensii venom. Based on molecular docking analysis, the top four candidates—MMTX, BmP05, BmTX1, and BmKK12—were selected for chemical synthesis, oxidatively cyclized to form their native disulfide-bridged conformations, and subsequently purified and characterized by analytical HPLC and MS. Calcium imaging confirmed that two of the four oxidized peptides, BmP05 and BmKK12, exhibited superior potency in inducing a sharp increase in Ca²⁺ influx. Crucially, BmP05 and BmKK12 demonstrated potent, concentration-dependent inhibition of Zika virus (ZIKV) replication at the RNA level at non-cytotoxic concentrations, whereas the weaker activators MMTX and BmTX1 did not. The current study first reports animal venom-derived peptides that function as specific TRPML2 agonists with concomitant antiviral activity. Together, our findings provide not only new molecular probes for dissecting TRPML2 biology but also a pioneering strategy for developing host-directed, broad-spectrum therapeutics against viruses dependent on endo-lysosomal entry. Full article

Emerging mosquito-borne flaviviruses, such as Dengue virus (DENV) and Zika virus (ZIKV), pose major global public health threats due to their geographic expansion, climate change, and the absence of effective antiviral therapies. Antiviral development against these pathogens has primarily focused on two complementary strategies. On the one hand, the blocking of viral replication by directly inhibiting essential viral enzymes, and on the other, enhancing the host’s innate immune defenses via targeted activation of intracellular antiviral pathways. Among the viral proteins required for replication, the NS2B–NS3 protease complex is one of the most conserved and druggable targets, prompting extensive efforts to design both covalent and non-covalent inhibitors. Covalent inhibitors, such as boronic acids, aldehydes, trifluoromethyl ketones, phenoxymethylphenyl derivatives, and α-ketoamides, form irreversible or slowly reversible bonds with the catalytic serine residue (Ser 135), producing long-lasting and high-affinity suppression of protease activity. In parallel, several classes of non-covalent, particularly allosteric, inhibitors have emerged as promising alternatives with improved specificity and reduced off-target reactivity. A complementary antiviral strategy involves the use of agonists of key innate immune sensors such as TLRs, RIG-I, and the cGAS–STING axis, which mediate the release of interferons (IFNs). This review brings together current knowledge on these two mechanistically distinct yet convergent approaches, highlighting how both can ultimately restrict flavivirus replication. Future opportunities involving modified peptide scaffolds, advanced delivery systems, and drug-repurposing strategies are finally discussed for the development of next-generation therapeutics against DENV and ZIKV. Full article

Glioblastoma (GBM) is an aggressive tumor with limited therapeutic options. Zika virus (ZIKV) has demonstrated activity against GBM; however, the cellular pathways behind this interaction remain unclear. We systematically reviewed open-access primary studies assessing differentially expressed genes (DEGs) in GBM models infected with wild-type or engineered ZIKV using transcriptomic approaches (inclusion criteria); reviews, restricted-access studies, commentaries, preprints, abstracts, and articles lacking data or not meeting these conditions were excluded (PROSPERO CRD420251077092). We performed a pathway analysis of reported DEGs. PubMed and Google Scholar were searched up to 5 March 2025; 139 records were identified and 5 met the eligibility criteria. Risk of bias was evaluated using an adapted ToxRTool for in vitro experiments and the SYRCLE RoB tool for in vivo models. Altogether, 4360 genes were reported as upregulated and 2072 as downregulated; 12 genes (DNAJB9, SESN2, PMAIP1, PPP1R15A, KLF4, ATF3, IFNB1, IFNL1, ANKRD33B, ZC3HAV1, OASL, and CCL5) were consistently upregulated, none were consistently downregulated. Pathway analysis of the studies providing complete DEG lists identified 23 commonly enriched pathways mostly related to interferon signaling. These findings may help guide future research in this field; nevertheless, methodological heterogeneity limits comparability, reinforcing the need for standardized protocols. Funding: ITpS, CNPq, and FAPEMIG. Full article

Flaviviruses such as dengue virus (DENV) and Zika virus (ZIKV) co-circulate widely and cause significant morbidity, yet effective broad-spectrum antivirals are limited. This study evaluated the antiviral efficacy, cytotoxicity, and host transcriptional responses to the nucleic acid–hydrolyzing antibody fragment 3D8 scFv in mono- and co-infection models. RNA sequencing of A549 cells treated with 3D8 scFv revealed a dose-dependent activation of the MAPK–HSP70 stress response, with minimal transcriptomic disruption at antiviral concentrations. Comparative transcriptomic analysis identified distinct host signatures for ZIKV and DENV2, and machine learning classifiers accurately distinguished infection states (AUC > 0.95). In Vero E6 cells, prophylactic treatment with 3D8 scFv significantly reduced viral RNA, protein expression, and infectious particle production for both viruses, including during co-infection. Optimized post-entry treatment also demonstrated antiviral activity. Cytotoxicity assays confirmed good tolerability at effective concentrations. These findings indicate that 3D8 scFv inhibits viral replication through early cleavage of viral nucleic acids while inducing a limited protective stress response, supporting its development as a broad-spectrum antiviral candidate. Full article

Background: Zika virus (ZIKV), a mosquito-borne flavivirus, is associated with congenital malformations and neuroinflammatory disorders, highlighting the need to identify host factors that shape infection outcomes. Macrophages, key targets and reservoirs of ZIKV, orchestrate both antiviral and inflammatory responses. Methods: Vitamin D (VitD) has emerged as a potent immunomodulator that enhances macrophage antimicrobial activity and regulates inflammation. To investigate how VitD shapes macrophage responses to ZIKV, we reanalyzed publicly available RNA-seq and miRNA-seq datasets from monocyte-derived macrophages (MDMs) of four donors, differentiated with or without VitD and subsequently infected with ZIKV. Results: Differential expression analysis identified long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and mRNAs integrated into competing endogenous RNA (ceRNA) networks. In VitD-conditioned and ZIKV-infected MDMs, 65 lncRNAs and 23 miRNAs were significantly modulated. Notably, lncRNAs such as HSD11B1-AS1, Lnc-FOSL2, SPIRE-AS1, and PCAT7 were predicted to regulate immune and metabolic genes, including G0S2, FOSL2, PRELID3A, and FBP1. Among the miRNAs, let-7a and miR-494 were downregulated, while miR-146a, miR-708, and miR-378 were upregulated, all of which have been previously implicated in antiviral immunity. Functional enrichment analysis revealed pathways linked to metabolism, stress responses, and cell migration. ceRNA network analysis suggested that SOX2-OT and SLC9A3-AS1 may act as molecular sponges, modulating regulatory axes relevant to immune control and viral response. Conclusions: Despite limitations in sample size and experimental validation, this study provides an exploratory map of ncRNA–mRNA networks shaped by VitD during ZIKV infection, highlighting candidate molecules and pathways for further studies on host–virus interactions and VitD-mediated immune regulation. Full article

Flaviviruses are responsible for significant morbidity and mortality worldwide. Despite intensive research, the structure and oligomerization properties of non-structural (NS) proteins, like NS2 or NS4, are still uncertain because of their high hydrophobicity. Solution NMR has shown that NS2B protein has two hydrophobic domains, organized as two short α-helical hairpins that contribute to both viral RNA replication and particle formation. These are separated by a hydrophilic loop that is a cofactor of protease NS3. However, the oligomerization behavior of NS2B has not been explored in detail. Herein, we have expressed Zika virus NS2B protein (ZIKV NS2B) and characterized its oligomerization in both detergent and lipids using crosslinking in liposomes, and mass photometry and analytical ultracentrifugation in detergent. We show that, in contrast to the small oligomers proposed earlier, ZIKV NS2B protein has a very complex oligomerization behavior, forming from dimers to very large multimers (>10) in both detergent and lipids. Although AlphaFold (AF) provided a model for monomeric NS2B that is consistent with available experimental data, no oligomeric model was predicted with confidence. We suggest that the role of the two short α-helical hairpins in membrane destabilization and reshaping host ER during viral infection may be aided or triggered by multimerization. Finally, although our results report a high tendency of NS2B to oligomerize, in the context of the infected cell, a biologically relevant multimeric complex may necessitate other viral proteins like NS4A or NS4B and/or host proteins. Full article