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Although flaviviruses, including DENV, ZIKV and JEV, remain important causes of febrile, congenital, and neurological diseases, treatment options remain largely supportive, with limited availability of virus-specific antiviral therapies. Marine organisms and marine-derived microorganisms produce chemically distinct antiviral materials, including sulfated polysaccharides, terpenoids, alkaloids, peptides, cyclodepsipeptides, and polyketides. However, their activities range from preliminary extract-level inhibition to direct biochemical target validation, making mechanistic comparison difficult. This review critically evaluates marine-derived anti-flaviviral agents using two complementary dimensions, the infection stage implicated by experimental assays and the strength of evidence supporting that assignment. DENV evidence is dominated by sulfated algal macromolecules that interfere with adsorption or internalization, whereas ZIKV studies encompass lipophilic algal metabolites, fungal alkaloids, cyclodepsipeptides, and a few target-oriented candidates. Across the field, most reports remain stage-associated rather than target-validated. Cross-study potency comparisons are constrained by differences in virus strains, cell models, assay formats, and treatment schedules. JEV-specific evidence is particularly sparse. Based on the DENV and ZIKV evidence map, we propose concise priorities for JEV-oriented discovery: early compound-level dereplication, parallel cytotoxicity testing, orthogonal confirmation of productive infection, stage-resolved assays, and biochemical or genetic validation of conserved flaviviral targets. This evidence-based framework can help distinguish promising chemical candidate scaffolds from preliminary antiviral signals and guide mechanism-informed development of marine-derived natural products against flaviviruses. Full article

Quinoline is a bicyclic aromatic heterocycle composed of a fused benzene and pyridine ring, and it has held an important place in medicinal chemistry for nearly two centuries. F. Runge first isolated it from coal tar in 1834, and it was later found to form the structural core of well-known natural products such as quinine, camptothecin, and γ-fagarine. Its asymmetric electron distribution, amphoteric character, and ability to undergo both electrophilic and nucleophilic substitution confer considerable pharmacophoric versatility on the quinoline scaffold. This review covers the chemistry and therapeutic relevance of quinoline derivatives, with an emphasis on their pharmacological significance rather than on their synthesis alone. It begins with a brief account of the scaffold’s structural features and main synthetic routes, then examines the biological activities reported for quinoline-based compounds, including antibacterial, anticancer, anti-inflammatory, antimalarial, antiparasitic, antitubercular, antioxidant, and antiviral activities, together with structure–activity relationships discussed at the level of specific ligand–target interactions where data allow. The last section covers more recent directions in quinoline-based drug discovery, including PROTAC degraders, kinase inhibitors, and multitarget-directed ligands, an area not extensively addressed in earlier reviews of this scaffold. The literature surveyed here shows that quinoline derivatives continue to serve as a versatile scaffold for generating new leads, linking established synthetic chemistry with current mechanistic and computational approaches. The continued diversification of quinoline-based chemotypes and their biological mechanisms reinforces the importance of this scaffold as a versatile platform for medicinal chemistry and drug discovery. Full article

A lifelong career devoted to the development of specific antiviral agents eventually yielded, besides (almost) 3000 publications, about ten antiviral compounds that were approved and marketed as antiviral drugs, i.e., DHPA (Duviragel^®), BVDU (Zostex^®, Mevir^®, Brivir^®…), VACV (Zelitrex^®, Valtrex^®), d4T (Stavudine^®), emivirine (Coactinon^®), rilpivirine (Edurant^®), HPMPC (Vistide^®), PMEA (Hepsera^®), tenofovir (Viread^®) and AMD-3100 (Mozobil^®), with the latter as a hematopoietic stem cell mobilizer. The targeted viruses for these compounds were herpes simplex virus (HSV), varicella-zoster virus (VZV), cytomegalovirus (CMV), human immunodeficiency virus (HIV), and hepatitis B virus (HBV). For other viruses, such as filo-, rhabdo-, arena-, myxo-, polyoma- and papillomaviruses, strategies have been elaborated that should facilitate future developments of antiviral drugs. Full article

Highly pathogenic RNA viruses, such as Ebola, SARS-CoV-2, and influenza, cause severe disease in humans. High mutation rates, which enable RNA viruses to evade immunity and escape antivirals, and their ability to spread from animals to humans and cause pandemics and outbreaks, make RNA viruses significant threats to public health. Diseases caused by Ebola, SARS-CoV-2, and influenza are prevented and treated with only a limited number of approved antiviral drugs, the effectiveness of which is limited by mutations in the viral targets. It is crucial to understand the structural determinants, molecular mechanisms, and host interactions of pathogenic RNA viruses to develop effective antiviral strategies. In this review, we discuss selected RNA viruses, focusing on the structure of their RNA polymerases and interactions with host factors during the different stages of the viral lifecycle, as well as the traditional antivirals targeting these structures and pathways. Furthermore, emerging concepts such as liquid–liquid phase separation and biomolecular condensates, and novel promising antiviral strategies are discussed. Understanding shared and distinct structures, molecular mechanisms, and host interactions across highly pathogenic RNA viruses enables the discovery of new and more effective antiviral strategies, ultimately improving clinical outcomes against evolving RNA viruses. Full article

Maraviroc (MVC), a CCR5 antagonist, has been proposed as a potential antiviral agent against SARS-CoV-2; however, its mechanism of action across viral variants remains unclear. Here, we evaluated the antiviral activity of MVC against SARS-CoV-2 wild-type (WT) and Omicron BA.1 variants using single-round infectious particles (SRIPs), virus-like particles (VLPs), and cell-based assays, with a focus on its impact on viral entry and Mpro function. MVC potently inhibited infection of both WT and BA.1 SRIPs in Vero E6 cells, exhibiting EC₅₀ values of 0.0065 μM and 0.016 μM, respectively. Time-of-addition assays revealed that MVC primarily targets the early phase of infection, with the strongest inhibition observed at the viral entry stage, while moderate effects were detected during attachment and post-entry stages. Fluorescence-labeled VLP imaging demonstrated distinct entry pathways, with WT predominantly entering via plasma membrane fusion and BA.1 via endocytosis, independent of cell type. MVC altered WT-VLP trafficking by promoting internalization and lysosomal localization, whereas it had minimal impact on BA.1 internalization. In spike-mediated cell–cell fusion assays, MVC preferentially inhibited WT spike-driven syncytium formation but showed limited effects on BA.1 or BA.4 fusion, while more effectively reducing Omicron spike-mediated binding. At the post-entry stage, MVC inhibited SARS-CoV-2 main protease (Mpro) activity, with BA.1 Mpro (P132H) exhibiting greater sensitivity (IC₅₀ = 0.496 µM) than WT (1.869 µM). Collectively, these findings demonstrate that MVC exerts variant-dependent antiviral effects by targeting viral entry, modulating trafficking pathways, and inhibiting Mpro activity. This study highlights MVC as a multi-stage inhibitor with differential efficacy against SARS-CoV-2 variants, providing insights into its potential therapeutic application. Full article

5′-Adenosine monophosphate-activated protein kinase (AMPK) is the principal cellular energy sensor that coordinates metabolic adaptation by balancing anabolic and catabolic pathways in response to energic stress. Beyond its canonical role in maintaining energy homeostasis, AMPK has emerged as a central regulator of host–pathogen interactions by integrating lipid metabolism, autophagy, mitochondrial dynamics, oxidative stress, and innate immune signaling. Flaviviruses, including dengue virus, Zika virus, West Nile virus, Japanese encephalitis virus, and yellow fever virus, extensively remodel host metabolism to establish productive infection. As a master regulator of cellular metabolism, AMPK can either restrict or facilitate flavivirus replication in a context-dependent manner by regulating lipid droplet biogenesis, fatty acid synthesis and beta-oxidation, autophagy, mitochondrial homeostasis, and interferon-mediated antiviral responses. Conversely, flaviviruses actively manipulate AMPK signaling and its downstream metabolic networks to promote endoplasmic reticulum remodeling, replication organelle biogenesis, energy production, and immune evasion. In this review, we summarize recent advances in understanding the multifaceted roles of AMPK during flavivirus infection, with an emphasis on its regulation of metabolic reprogramming, organelle remodeling, and antiviral immunity. We further discuss the therapeutic potential of pharmacologically targeting AMPK and its downstream pathways as a host-directed strategy for broad-spectrum antiviral intervention against flaviviruses. Full article

Infectious bovine rhinotracheitis virus (IBRV) causes highly contagious bovine respiratory disease and threatens the global cattle industry. Ferroptosis, an iron-dependent regulated cell death, is involved in multiple viral infections, but its role and mechanism in IBRV infection remain unclear. This study investigated IBRV-induced ferroptosis and the NFKB1-SLC39A8 axis in MDBK cells and examined the effect of ferroptosis on IBRV replication. Ferroptotic phenotypes and molecules were detected by biochemical assays, qPCR, Western blotting and TEM. Gain- and loss-of-function assays were performed to modulate gene expression, and their transcriptional relationship was verified by dual-luciferase assay. IBRV induced typical ferroptosis in MDBK cells, including Fe²⁺ overload, excessive ROS and MDA accumulation, GSH depletion and mitochondrial damage. Ferrostatin-1 reversed these changes and reduced viral titers, suggesting that ferroptosis contributes to IBRV replication. SLC39A8 overexpression aggravated ferroptosis, whereas its knockdown suppressed it. Mechanistically, our data support that NFKB1 positively regulates SLC39A8 transcription, and NFKB1 silencing inhibited IBRV-induced ferroptosis. In conclusion, this in vitro study shows that IBRV induces ferroptosis in MDBK cells via the NFKB1-SLC39A8 axis, and ferroptosis may contribute to viral replication. These findings provide insights into IBRV–host cellular interaction and identify potential candidate molecular targets for future antiviral research. Full article

SARS-CoV-2 relies on a virus-encoded RNA capping pathway to produce 5′ cap structures that are essential for mRNA stability, efficient translation, and evasion of host innate immune surveillance. Within this pathway, nonstructural protein 14 (nsp14) catalyzes N7 methylation of the guanine cap, a key step that converts the cap core into a functional Cap-0 structure and enables subsequent maturation. Owing to its essential role in viral replication and its high conservation across coronaviruses, nsp14 has emerged as an attractive antiviral target. Recent structural and biochemical studies have elucidated the architecture of the nsp14 N7-methyltransferase domain, revealing an S-adenosyl-L-methionine (SAM)-dependent fold with a defined cofactor-binding site and an adjacent cap-binding pocket that orients the RNA substrate for methyl transfer. These insights have guided the development of diverse inhibitor classes, including SAM-competitive analogs, bisubstrate-like compounds, and non-nucleoside inhibitors identified through screening approaches. While early SAM-like inhibitors demonstrated target tractability, their therapeutic potential has been limited by challenges in selectivity and cellular permeability. More recent inhibitors that target the cap-binding pocket or exploit product-assisted ternary complex mechanisms highlight alternative strategies for achieving improved potency and specificity. Despite these advances, current structural models rely on truncated RNA substrates and isolated protein constructs, which may not fully capture the native catalytic environment. Future efforts to resolve nsp14 within the replication–transcription complex and develop novel inhibition strategies will be critical for advancing mechanistic understanding and antiviral development. Full article

Superoxide dismutase 2 (SOD2), a key mitochondrial antioxidant enzyme, is essential for maintaining cellular redox homeostasis by scavenging superoxide radicals. While viruses often induce oxidative stress, the specific role of SOD2 in antiviral defense remains unclear. Here, we report that vaccinia virus (VACV) infection triggers mitochondrial and cellular reactive oxygen species (ROS) and selectively upregulates SOD2, but not SOD1. Genetic knockout of SOD2 exacerbated mitochondrial ROS (mtROS) accumulation and significantly enhanced VACV replication and spread, resulting in larger viral plaques. Conversely, SOD2 overexpression constrained plaque formation and suppressed viral dissemination. Mechanistically, the antiviral function of SOD2 does not strictly rely on its enzymatic activity or mitochondrial targeting, as neither the deacetylation-mimicking mutant nor the mutant lacking the mitochondrial localization signal peptide appreciably impaired its antiviral potency. Furthermore, in a rabbit model, local overexpression of human SOD2 attenuated the poxvirus lesion formation. Our findings unveil an important yet easily overlooked role of SOD2 in antiviral defense and posit it as a promising candidate for the development of host-directed therapeutics against poxviruses. Full article

Kidney transplant recipients (KTRs) face a significantly elevated risk of persistent high-risk human papillomavirus (HR-HPV) infection and subsequent anal squamous cell carcinoma (ASCC) due to chronic immunosuppressive therapy impairing immunosurveillance. Despite the markedly increased risk of ASCC in this vulnerable cohort, standardized screening protocols and optimal clinical management guidelines are not exhaustive. Chronically compromised immunosurveillance permits prolonged HR-HPV carriage and viral genome integration, driving oncogenesis via the E6 and E7 oncoproteins. While calcineurin inhibitors exert pro-oncogenic effects, transitioning to mTOR inhibitors offers distinct antiproliferative and antiviral advantages. Early detection relies on risk-stratified screening utilizing digital anorectal examination, anal cytology, and high-resolution anoscopy. For managing anal intraepithelial neoplasia, traditional topical agents and minimally invasive ablative procedures are widely used, although high recurrence rates present a major clinical challenge. This review analyzes HPV pathogenesis and clinical management in KTRs, evaluating the impact of immunosuppressive regimens and exploring innovative diagnostic and therapeutic strategies. To address viral persistence without compromising the allograft, integrating novel non-invasive, target-specific nutraceuticals may represent an interesting complementary approach. Ultimately, mitigating post-transplant ASCC requires a multidisciplinary strategy that couples early localized screening with tailored systemic immunosuppression. Full article

Stop codon readthrough is a noncanonical translation strategy employed by certain RNA viruses, in which a viral termination codon is either decoded by host near-cognate tRNAs or canonically recognized by the class I release factor (RF, eRF1 in eukaryotes). Ribosomal A-site competition between near-cognate tRNAs and eRF can shift decoding toward near-cognate tRNAs, thereby promoting non-canonical decoding events by transiently pausing termination and favoring readthrough. This review focuses on two viral cis-elements that modulate readthrough across four viral genera in which this decoding event has been experimentally validated: (i) primary sequences surrounding the stop codon (stop codon context), and (ii) downstream RNA structures. Effects of stop codon context have been observed more broadly in cellular genes, including nonsense suppression in bacteria, with mechanisms including inefficient RF association or tRNA interactions at adjacent sense codons. In eukaryotic systems, interactions with the ribosomal mRNA entry channel have been suggested. Diverse downstream structures, including gammaretroviral pseudoknots and specific structures in alpha- and coltiviruses, further stimulate readthrough in a location- and structure-sensitive manner. This effect has not been consistently observed in chikungunya and triatoviral structures, suggesting a strong dependence on local sequence and structural context. Compared with the larger number of cellular readthrough occurrences that can be detected at low efficiency by ribosome profiling, viral readthrough in mammalian systems is consistently high (>2%). Understanding the interplay between viral RNA elements and host translational machinery, including potential kinetic trapping at the termination codon, provides insights into this unusual elongation mechanism. These findings may have implications for antiviral strategies targeting these RNA elements. Full article

The red-spotted grouper nervous necrosis virus (RGNNV) exhibits high pathogenicity in larval C. sonnerati, yet the immune molecular mechanism remains unclear. Non-coding RNAs (ncRNAs) are vital in the host’s immune responses during viral infection. However, there has been no study on ncRNA research for this species to date. We systematically identified 105 DE microRNAs (miRNAs), 157 DE long non-coding RNAs (lncRNAs) and 31 DE circular RNAs between the infection group and control group. Functional enrichment analysis revealed that these differentially expressed genes were significantly enriched in pathways associated with innate immune defense, inflammatory, and cell death, such as JAK-STAT signaling pathway, NF-κB signaling pathway, apoptosis, and necroptosis. Furthermore, the lncRNA–miRNA–mRNA interaction network involving miR-93 was constructed, which may represent a promising candidate therapy target for future investigations. This study presents the first comprehensive ncRNA transcriptome dataset of C. sonnerati infected with RGNNV, identifies key antiviral defense and cell death-related genes and hub pathways, and thereby identifies miR-93-involved lncRNA–miRNA–mRNA network and key targeted genes (STAT1, TRIM25, UNC93B, IL12RB1, IRF8, CDKN1A, FCGR1A) as hub molecular regulators in immune response of this species. Full article

Background: Elranatamab, a bispecific antibody targeting BCMA and CD3, has demonstrated clinical activity in relapsed/refractory multiple myeloma. Real-world evidence regarding infectious complications and supportive care remains limited. We evaluated the early clinical activity, safety profile, infectious complications, and supportive care practices associated with relapsed/refractory multiple myeloma (RRMM). This study represents one of the first multicenter real-world evaluations of elranatamab in Türkiye. Methods: This multicenter retrospective study included 87 patients with relapsed/refractory multiple myeloma treated with elranatamab. Clinical characteristics, treatment responses, immune-mediated toxicities, infectious complications, and supportive care practices were assessed. Overall response rate (ORR), progression-free survival (PFS), and overall survival (OS) were evaluated. Multivariable analyses were performed to identify factors associated with treatment response and clinical outcomes. Results: At 3 months, ORR was 47.1% in the ITT population, 54.7% in the mITT population, and 83.7% among evaluable patients; corresponding 6-month ORRs were 31.0%, 42.2%, and 81.8%, respectively. The high proportion of patients without landmark response assessments primarily reflected insufficient follow-up, early death, or disease progression. Elevated LDH remained independently associated with lower response probability and inferior clinical outcomes. Cytokine release syndrome (CRS) occurred in 69% of patients, with grade ≥ 3 events in 5.7%, whereas immune effector cell-associated neurotoxicity syndrome (ICANS) was infrequent (4.6%) and no grade ≥ 3 events occurred. Grade ≥ 3 infections occurred in 39% of patients, including CMV events requiring antiviral treatment in 24.1%. No HBV reactivation occurred among patients receiving antiviral prophylaxis. Median PFS and OS were 8.1 and 10.6 months, respectively. Conclusions: Elranatamab demonstrated early clinical activity and a manageable safety profile in a heavily pretreated real-world RRMM population. Infectious complications, including CMV events, remained clinically relevant, emphasizing the importance of supportive care. Longer follow-up is needed to characterize long-term outcomes. Full article

Kaposi’s Sarcoma Herpesvirus (KSHV) is the etiological agent of Kaposi’s Sarcoma (KS), which induces metabolic stress in infected host cells. KSHV reprograms host metabolic pathways for efficient viral replication and infectious virion production. Here, we report a time-course global metabolomics study conducted in iSLK.BAC16 cells to compare latent and lytic KSHV infection. Our data show that amino acid, central carbon, and nucleotide metabolic pathways are highly dysregulated upon reactivation. During lytic KSHV infection, pathway enrichment analysis identifies purine and pyrimidine metabolism as the top two most significantly impacted and dysregulated pathways. Further experiments have shown that nucleotide metabolism is required during lytic KSHV infection to produce maximal infectious virus. Treatment with the FDA-approved drug, methotrexate (MTX), a folate antagonist that decreases nucleotide metabolism by reducing tetrahydrofolate cofactors, significantly reduced KSHV copy number and late lytic viral gene expression upon reactivation compared to controls. Additionally, titers of cell-free supernatants from MTX-treated lytic samples showed a significant reduction in infectious virion production. Furthermore, MTX significantly decreased the viral titer of murine herpesvirus 68 (MHV-68), a model virus to study gammaherpesvirus. Overall, our study demonstrates that metabolic inhibition during lytic gammaherpesvirus infection decreases productive infection and hence serves as a potential therapeutic antiviral target. Full article

Hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis D virus (HDV), together with HIV and bacterial sexually transmitted infections (STIs), account for a rising toll of more than one million deaths annually and overlap within shared behavioral and social networks, yet are still diagnosed through separate, pathogen-specific pathways. This narrative review synthesizes contemporary evidence on the convergence between viral hepatitis, HIV, and high-risk STI groups—men who have sex with men, pre-exposure prophylaxis (PrEP) users, people practicing chemsex, people who inject drugs, incarcerated populations, and migrants from endemic regions—and characterizes the diagnostic technologies and linkage-to-care models available to address it. Despite effective antivirals, the diagnostic cascade remains the principal bottleneck: most people with chronic HCV are undiagnosed, and HDV—with a pooled anti-HDV seroprevalence of approximately 4.5% among HBsAg-positive individuals—is its clearest expression, as most carriers are never tested. Reflex algorithms, multiplex panels, point-of-care assays, dried blood spots, and electronic health record alerts are validated but unevenly implemented. We argue that, alongside persistent resource, political, and equity-related constraints, a substantial share of the remaining barriers is operational rather than purely technological, and propose a practical, STI-clinic-centered framework integrating reflex testing, population-specific periodicity, and explicit linkage pathways toward the WHO 2030 elimination targets. Full article