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Viral infections are responsible for several chronic and acute diseases in both humans and animals. Despite the incredible progress in human medicine, several viral diseases, such as acquired immunodeficiency syndrome, respiratory syndromes, and hepatitis, are still associated with high morbidity and mortality rates in humans. Natural products from plants or other organisms are a rich source of structurally novel chemical compounds including antivirals. Indeed, in traditional medicine, many pathological conditions have been treated using plant-derived medicines. Thus, the identification of novel alternative antiviral agents is of critical importance. In this review, we summarize novel phytochemicals with antiviral activity against human viruses and their potential application in treating or preventing viral disease.

Due to their antimicrobial and antiviral activity potential in vitro, polyphenols are gaining a lot of attention from the pharmaceutical and healthcare industries. A novel antiviral and antimicrobial approach could be based on the use of polyphenols obtained from natural sources. Here, we tested the antibacterial and antiviral effect of a mix of polyphenols present in natural almond skin (NS MIX). The antimicrobial potential was evaluated against the standard American Type Culture Collection (ATCC) and clinical strains of Staphylococcus aureus, including methicillin-resistant (MRSA) strains, by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Herpes simplex virus type I was used for the antiviral assessment of NS MIX by plaque assay. Furthermore, we evaluated the expression of viral cascade antigens. NS MIX exhibited antimicrobial (MIC values of 0.31–1.25 mg/ml) and antiviral activity (decrease in the viral titer ** p < 0.01, and viral DNA accumulation * p < 0.05) against Staphylococcus aureus and HSV-1, respectively. Amongst the isolated compounds, the aglycones epicatechin and catechin showed the greatest activity against S. aureus ATCC 6538P (MIC values of 0.078–0.15 and 0.15 mg/ml, respectively), but were not active against all the other strains. These results could be used to develop novel products for topical use.

Graphene-based nanomaterials exhibit exceptional physicochemical properties that facilitate a range of diverse biomedical applications, including liquid biopsy. In this study, graphene-based magnetic units, termed MAGU (MAGnetic Units), were specifically engineered for the selective isolation of exosomes. Total extracellular vesicles were first enriched using ultracentrifugation, followed by immunomagnetic capture of CD9+ exosomes. MAGU functionalized with anti-CD9 antibody (MAGU-anti-CD9) efficiently recovered a CD9-positive exosome subpopulation expressing canonical markers ALIX, CD147, TSG101, and Flotillin-1, thereby confirming selective isolation performance. To investigate viral associated signaling, 293T cells were transduced with SARS-CoV-2 spike pseudovirus. This pseudovirus was engineered to express the SARS-CoV-2 spike protein, enabling simulation of viral entry and assessment of potential alterations in the exosomal profile induced by viral binding. Exosomes released by pseudovirus-transduced 293T cells were analyzed and compared to those from non-transduced controls. The MAGU-anti-CD9 complex selectively isolated a defined subset of CD9-positive vesicles enriched in the multifunctional transmembrane glycoprotein CD147, which has been proposed as a cofactor in SARS-CoV-2 entry. Comprehensive molecular profiling of selectively captured exosome subpopulations is expected to further support the application of MAGU technology in virus–host interaction research and liquid-biopsy-based diagnostics.

In recent years, great interest has been committed to the search for alternative clinical treatments for herpetic infections that reduce side effects, overcome drug resistance, and combat the intense inflammatory response triggered by viral infection. Pistachios ( Pistacia vera L. ) are known to contain polyphenols, pharmacologically active compounds with both immunomodulatory and antiviral activities. The present work investigates the antiviral properties of pistachio extracts against HSV-1 and their potential immunomodulatory effect on human monocytic cells, with a focus on NF-κB signaling. The RT2 Profiler PCR array was used to identify differential expression of chemokines during infection and pretreatment. We discovered that HSV-1 induces potent cytokine and chemokine activation in monocytes, and that this activation is significantly reduced by in vitro treatment with pistachio extracts. Our focus included CXCL10, CXCL11, CCL13, CCL2, CCL4, CCL13 and the receptor CMKLR1, which were particularly expressed after HSV-1 replication and downregulated by pretreatment with pistachio extracts. We further confirmed this inhibitory activity using zeaxanthin, a bioactive carotenoid found in pistachios, which has previously shown to inhibit HSV-1 replication in permissive cells. In addition, by blocking viral replication with phosphonoacetic acid (PAA), we demonstrated that in HSV-1-infected THP-1 cells, activation of CXCL10, CXCL11, CCL13, CCL2, CCL4, CCL13 and CMKLR1 was significantly downregulated, suggesting that chemokine activation is partially dependent on active HSV-1 replication. Lastly, using THP-1-dnIκBα cells, we have demonstrated that chemokine accumulation was correlated with HSV-1-induced NF-κB activation. Importantly, when neuronal (SH-SY5Y) and epithelial (HEp-2) cells were exposed to supernatants derived from pistachio extracts and zeaxanthin-treated infected THP-1 cells, we observed a significant reduction in the production of new HSV-1 viral progeny compared to the untreated infected THP-1 cells. In conclusion, the study highlights the use of pistachio extracts and zeaxanthin as a promising therapeutic approach against HSV-1. Notably, it offers valuable insights into the complex virus-host interaction, demonstrating how HSV-1 modulates the chemokine-mediated cell response, including CXCL10, CXCL11, CCL13, CCL2, and CCL4, and the receptor CMKLR1, to maintain a delicate balance with the host cell, thereby promoting viral persistence.

The application of nanotechnology in medicine has garnered significant interest, particularly in the development of advanced drug delivery systems. Graphene oxide (GO) shows promise as a carrier for delivering microRNA (miRNA) mimics or antisense constructs. miRNAs play a crucial role in regulating gene expression, and their dysregulation is associated with various diseases, including cancer. This study aimed to evaluate the impact of graphene oxide on cellular signaling pathways and its potential as a platform for gene delivery by developing a GO–antisense miRNA-21 nanosystem in HepG2 liver cancer cells. A colloidal dispersion of GO was used to prepare GO-antisense miRNA-21 nanosystems via self-assembly. The nanosystem was characterized in terms of ultrastructure, size distribution, surface composition and binding by TEM, DLS, ATR-FTIR and UV-Vis spectra. Zeta potential measurements were conducted to evaluate nanosystem stability by assessing the release kinetics of antisense miRNA-21. The efficiency of the GO nanosystem in delivering antisense miRNA-21 into HepG2 cells was analyzed using confocal microscopy and flow cytometry. Given the central role of miRNA-21 in inflammatory and oncogenic pathways, we first assessed its expression following GO exposure. In line with previous studies reporting high miRNA-21 expression in hepatocellular carcinoma cells, GO treatment further increased miRNA-21 levels in HepG2 cells compared with untreated controls. Changes in the expression levels of IL-8, MCP-1, ICAM-1, TIMP-2, and NF-kB were quantified by qPCR analysis. The ultrastructural analysis confirmed a strong affinity between GO and antisense miRNA-21. Transfection results demonstrate that the GO-based nanosystem effectively delivered antisense miRNA-21 into HepG2 cells, leading to a reduction in the expression of key pro-inflammatory genes. These findings suggest that GO-based nanocarriers may offer a promising strategy for delivering localized intratumoral miRNA-based therapies that target gene regulation in hepatocellular carcinoma.

Graphene oxide (GO) is a promising nanocarrier for the delivery of oligonucleotides. It offers a high loading capacity, efficient cellular uptake, and surface functionalization. MicroRNA-21 (miR-21) is a well-characterized oncomiR commonly overexpressed in hepatocellular carcinoma (HCC). In HCC, miR-21 contributes to tumor progression, inflammation, and angiogenesis. In a previous in vitro study, we showed that GO alone induces the upregulation of pro-inflammatory and tumor-related genes in HepG2 cells. However, conjugation with an antisense miR-21 (GO-antisense miRNA 21) reverses this effect, suggesting a potential therapeutic application. This study aims to evaluate the antitumor and anti-angiogenic efficacy of the GO-antisense miR-21 nanosystem in ovo using the chick embryo chorioallantoic membrane (CAM) model. Fertilized chicken eggs (n = 4 per group) were randomized into untreated, GO-treated, and GO–antisense miR-21-treated cohorts. A dose of 200 μL (GO 10.0 µg/mL: antisense miR-21 5.0 pmol/mL) was administered intratumorally. Tumor size, volume, and vascularization were monitored through stereomicroscopy and histological analysis. The expression of inflammatory and tumor-associated genes (IL-8, MCP-1, TIMP-2, ICAM-1 and NF-kB) was assessed by quantitative PCR. Given its prominent response, IL-8 protein expression was further analyzed via immunofluorescence. To evaluate tumor-specific delivery, FITC-labeled GO was tracked by confocal microscopy. Our data revealed that treatment with unfunctionalized graphene oxide (GO) unexpectedly promoted tumor vascularization and led to a significant increase in tumor weight. This was accompanied by upregulation of inflammatory markers. In contrast, GO-antisense miR-21 significantly reduced the tumor volume and vessel density. It also successfully downregulated all target genes. Confocal imaging demonstrated preferential accumulation of the nanosystem within the tumor mass. Our results highlight the dual anti-inflammatory and anti-angiogenic effects of GO-antisense miRNA 21 in ovo and support its potential as a targeted nanoplatform for HCC treatment.

The HSV-1 tegument protein Us11 counteracts the antiviral defense mechanisms by precluding the host protein shutoff. Previous works demonstrated that Us11 prevents heat-and staurosporine-induced apoptosis and inhibits autophagy. Therefore, in the present study, we investigated the hypothesis that HSV-1, through Us11, could recruit caspase-8, a key enzyme regulating programmed cell death. We first show that HSV-1 promotes the accumulation of caspase-8-p18 active fragments in both semi permissive THP-1 cells and fully permissive HEp-2 cells to HSV-1 replication. Using a recombinant virus R3630 (ΔUs11/ΔUs12) and a plasmid encoding Us11-recombinant protein we have proven that Us11 promotes p18 accumulation, which does not trigger the apoptotic signaling. Additional, in an in vitro model, we demonstrated that Us11-recombinant protein induces caspase-8-p18 cleavage by physically interacting with the caspase-8 recombinant protein. Finally, we found that, during HSV-1 replication, activated-caspase-8 cleaves Atg3 protein to potentially block autophagy and support its replication.

To replicate, spread and persist in the host environment, viruses have evolved several immunological escape mechanisms via the action of specific viral proteins. The model “host shut off” adopted by virion host shut off (VHS) protein of Herpes simplex type 1 (HSV-1) represents an immune evasion mechanism which affects the best-characterized component of the innate immunological response, protein kinase R (PKR). However, up to now, the real mechanism employed by VHS to control PKR is still unknown. In this paper, we implement and extend our previous findings reporting that wild-type HSV-1 is able to control PKR, whereas a VHS mutant virus (R2621) clearly induces an accumulation of phosphorylated PKR in several cell types in a VHS-RNase activity-dependent manner. Furthermore, we demonstrate for the first time a new PKR-regulatory mechanism based on the involvement of Us3 and UL13 tegument viral proteins. The combined approach of transfection and infection assay was useful to discover the new role of both viral proteins in the immunological escape and demonstrate that Us3 and UL13 control the accumulation of the phosphorylated form (ph-PKR). Lastly, since protein kinases are tightly regulated by phosphorylation events and, at the same time, phosphorylate other proteins by inducing post-translational modifications, the interplay between Us3 and VHS during HSV-1 infection has been investigated. Interestingly, we found that VHS protein accumulates at higher molecular weight following Us3 transfection, suggesting an Us3-mediated phosphorylation of VHS. These findings reveal a new intriguing interplay between viral proteins during HSV-1 infection involved in the regulation of the PKR-mediated immune response.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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.