Reduced Virus Titers Research Articles

The Combination of GS-441524 (Remdesivir) and Ribavirin Results in a Potent Antiviral Effect Against Human Parainfluenza Virus 3 Infection in Human Airway Epithelial Cell Cultures and in a Mouse Infection Model

Human parainfluenza virus type 3 (HPIV-3) can cause severe respiratory diseases, particularly in young children, the elderly and immunocompromised. There are no approved antiviral drugs against this virus. We report that the combination of ribavirin with either remdesivir or its parent nucleoside GS-441524 results in a pronounced antiviral effect against HPIV-3 in LLC-MK2 cells and in human airway epithelial cells grown at the air–liquid interface. In AG129 mice intranasally inoculated with HPIV-3, the combined treatment with ribavirin and GS-441524 decreased infectious viral lung titers by >2.5 log10 to undetectable levels in 4 out of 11 mice and by 1.6 log10 in the remaining 7 mice as compared with the vehicle. The lungs of all mice that received the combined treatment appeared histologically normal or virtually normal, whereas 8 of 11 vehicle-treated mice presented with bronchopneumonia. By contrast, ribavirin alone did not result in a reduction in infectious viral lung titers; GS-441524 alone reduced infectious viral lung titers by 1.2 log10. Moreover, several mice in the single-treatment groups exhibited severe lung pathology. These findings may warrant exploring this combination in patients with severe HPIV-3 infections and possibly also against infections with other viruses that are susceptible in vitro to these two drugs.

Fc-binding nanodisc restores antiviral efficacy of antibodies with reduced neutralizing effects against evolving SARS-CoV-2 variants

Passive antibody therapies, typically administered via parenteral routes, have played a crucial role in the initial response to the COVID-19 pandemic. However, the ongoing evolution of SARS-CoV-2 has revealed significant limitations of this approach, primarily due to mutational escape and the inadequate delivery of antibodies to the upper respiratory tract. To overcome these challenges, we propose a novel prophylactic strategy involving the intranasal delivery of an antibody in combination with an Fc-binding nanodisc. This nanodisc, engineered to specifically bind to the Fc regions of IgG antibodies, served two key functions: extending the antibody's half-life in the larynx and trachea, and enhancing its neutralization efficacy. Notably, Sotrovimab, an FDA-approved monoclonal antibody that has experienced a significant decline in neutralizing potency due to viral evolution, exhibited robust antiviral activity when complexed with the nanodisc against all tested Omicron variants. Furthermore, the Fc-binding nanodisc significantly boosted the antiviral efficacy of the soluble angiotensin-converting enzyme 2 (sACE2) Fc fusion protein, which possesses broad but modest antiviral activity. In ACE2 transgenic mice, the Fc-binding nanodisc protected better than sACE2-Fc alone with two more log reduction in lung viral titer. Therefore, the intranasal Fc-binding nanodisc offers a promising and powerful approach to counteract the diminished antiviral activity of neutralizing antibodies caused by mutational escape, effectively restoring antiviral efficacy against various evolving SARS-CoV-2 variants.

Ubiquitin-like modifier-activating enzyme 1 interacts with Zika virus NS5 and promotes viral replication in the infected cell.

Translation errors, impaired folding or environmental stressors (e.g. infection) can all lead to an increase in the presence of misfolded proteins. These activate cellular responses to their removal, including intracellular protein degradation activities. Protein ubiquitylation is involved in two major degradation pathways, the ubiquitin-proteasome system and selective autophagy. In humans, the ubiquitin-like modifier-activating enzyme 1 (UBA1) is the primary E1 enzyme in the ubiquitin conjugation cascade. Viruses have evolved to exploit protein degradation pathways to complete their infection cycles. Zika virus (ZIKV) is an emerging orthoflavivirus causing serious neurologic disorders in neonates (congenital microcephaly) and adults (Guillain-Barré syndrome). Non-structural protein 5 (NS5), the largest and most conserved protein in the orthoflaviviruses, catalyses the synthesis and capping of new viral genomes. In addition to viral RNA replication in the cytoplasm, ZIKV NS5 is translocated into the nucleus to interfere with host antiviral responses. Here, we demonstrate that ZIKV NS5 co-immunoprecipitates with cellular UBA1. Immunofluorescence assays suggest that this interaction takes place primarily in the nucleus of an infected cell, although colocalization of both proteins is also detected in the cytosol. RNA interference-mediated depletion of UBA1 leads to reduced virus titres in the infected cells, while transient overexpression of UBA1 favours faster replication kinetics, with higher virus titres and protein levels detected. Moreover, UBA1-targeting drugs cause significant drops in virus infectivity. These results support a proviral role for UBA1 during ZIKV infection and encourage the potential use of inhibitors against this enzyme or its NS5-interacting epitopes as potential therapeutic targets.

Porcine reproductive and respiratory syndrome virus infection induces glycolysis of macrophages to facilitate viral replication

This work aims to explore the effect of glycolysis on the replication of porcine reproductive and respiratory syndrome virus (PRRSV) in porcine alveolar macrophages (PAMs). The changes of glucose metabolism, PRRSV protein levels, PRRSV titers, and the relative expression levels of genes and proteins in PAMs were analyzed by ELISA, qPCR, virus titration, and Western blotting after PRRSV infection. The effect of hypoxia-inducible factor-1α (HIF-1α) on PRRSV replication was subsequently assessed by specific siRNAs targeting to HIF-1α. The results showed that PRRSV infection enhanced glycolysis, elevated the levels of glucose uptake and lactate in the supernatant (P<0.05 and 0.01, respectively), reduced ATP production (P<0.05), and up-regulated the expression of hexokinase 2 (HK2), 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3 (PFKFB3), and pyruvate kinase isozyme type M2 (PKM2) in PAMs (P<0.05 and 0.01, respectively). Glycolysis inhibitors down-regulated the expression of PRRSV proteins and reduced virus titers (P<0.01). The knockdown of HIF-1α by siRNAs inhibited glycolysis and lowered PRRSV titers (P<0.05). In addition, the interferon pathways inhibited by PRRSV infection were reversed by the inhibition of glycolysis. These findings may facilitate further investigation of the role of glycolysis in PRRSV replication.

The inactivation of the Niemann Pick C1 cholesterol transporter restricts SARS-CoV-2 entry into host cells by decreasing ACE2 abundance at the plasma membrane

BackgroundThe Niemann Pick C1 (NPC1) protein is an intracellular cholesterol transporter located in the late endosome/lysosome (LE/Ly) that is involved in the mobilization of endocytosed cholesterol. Loss-of-function mutations in the NPC1 gene lead to the accumulation of cholesterol and sphingolipids in LE/Ly, resulting in severe fatal NPC1 disease. Cellular alterations associated with NPC1 inactivation affect both the integrity of lipid rafts and the endocytic pathway. Because the angiotensin-converting enzyme 2 (ACE2) and type 2 serine transmembrane protease (TMPRSS2), interactors of the SARS-CoV-2 Spike protein also localize to lipid rafts, we sought to investigate the hypothesis that NPC1 inactivation would generate an intrinsically unfavorable barrier to SARS-CoV-2 entry.ResultsIn this study, we show that inhibition of the cholesterol transporter activity of NPC1 in cells that express both ACE2 and TMPRSS2, considerably reduces SARS-CoV-2 infectivity, evaluated as early as 4 h post-infection. Mechanistically, treatment with NPC1 specific inhibitor U18666A relocalizes ACE2 from the plasma membrane to the autophagosomal/lysosomal compartment, thereby reducing SARS-CoV-2 entry into treated cells. Reduction of viral entry was observed for both fully infectious SARS-CoV-2 virus and with a pseudotyped VSV-Spike-GFP virus. For instance, U18666A-treated Caco-2 cells infected with the pseudotyped VSV-Spike-GFP showed a > threefold and > 40-fold reduction in virus titer when infectivity was measured at 4 h or 24 h post-infection, respectively. A similar effect was observed in CRISP/R-Cas9-edited Caco-2 cells, which were even more resistant to SARS-CoV-2 infection as indicated by a 97% reduction of viral titers.ConclusionOverall, this study provides compelling evidence that the inhibition of NPC1 cholesterol transporter activity generates a cellular environment that hinders SARS-CoV-2 entry. ACE2 depletion from the plasma membrane appears to play a major role as limiting factor for viral entry.

4-Substituted-2-Thiazole Amides as Viral Replication Inhibitors of Alphaviruses.

2-(Methylthio)-N-(4-(naphthalen-2-yl)thiazol-2-yl)nicotinamide 1 was identified as an inhibitor against Chikungunya virus (CHIKV) with good antiviral activity [EC50 = 0.6 μM; EC90 = 0.93 μM and viral titer reduction (VTR) of 6.9 logs at 10 μM concentration] with no observed cytotoxicity (CC50 = 132 μM) in normal human dermal fibroblast (NHDF) cells. Structure-activity relationship (SAR) studies to further improve the potency, efficacy, and drug-like properties of 1 led to the discovery of a new potent inhibitor N-(4-(3-((4-cyanophenyl)amino)phenyl)thiazol-2-yl)-2-(methylthio)nicotinamide 26, which showed a VTR of 8.7 logs at 10 μM against CHIKV and an EC90 of 0.45 μM with considerably improved MLM stability (t1/2 = 74 min) as compared to 1. Mechanism of action studies show that 26 inhibits alphavirus replication by blocking subgenomic viral RNA translation and structural protein synthesis. The in vivo efficacy studies of compound 26 on CHIKV infection in mice are reported.

The IL-33/ST2 signaling axis drives pathogenesis in acute SARS-CoV-2 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), remains a significant threat to global public health. Immunopathological damage plays a role in driving pneumonia, acute respiratory distress syndrome (ARDS), and multiorgan failure in severe COVID-19. Therefore, dissecting the pulmonary immune response to SARS-CoV-2 infection is critical to understand disease pathogenesis and identify immune pathways targetable by therapeutic intervention. Considering that the type 2 cytokine IL-13 enhances COVID-19 disease severity, therapeutic targeting of upstream signals that drive type 2 immunity may confer further protection. In this study, we investigate the role of the IL-33/ST2 signaling axis, a potent inducer of type 2 immunity in the lung, in a mouse model of COVID-19. Upon infection with mouse-adapted SARS-CoV-2 MA10, ST2 -/- mice had significantly improved weight loss and survival (69.2% vs 13.3% survival; P = 0.0005), as compared to wild-type mice. In a complementary pharmacologic approach, IL-33/ST2 signaling was inhibited using HpBARI_Hom2, a helminth derived protein that binds to mouse ST2 and blocks IL-33 signaling. In SARS-CoV-2 MA10 infection, HpBARI_Hom2-treated mice had significantly improved weight loss and survival (60% vs 10% survival; P = 0.0035), as compared to inert control-treated mice. These data demonstrate that loss of IL-33/ST2 signaling confers protection during acute SARS-CoV-2 MA10 infection, implicating the IL-33/ST2 signaling axis as an enhancer of COVID-19 disease severity. The protection conferred by pharmacologic blockade of IL-33/ST2 signaling was independent of viral control, as HpBARI_Hom2-treated mice had no reduction in viral titers. This finding suggests an immunopathogenic role for IL-33/ST2 signaling. One potential mechanism through which IL-33/ST2 signaling may drive severe disease is through enhancement of type 2 immune pathways including IL-5 production, as pulmonary IL-5 concentrations were found to depend on IL-33/ST2 signaling in acute SARS-CoV-2 MA10 infection.

Selective and complementary antimicrobial and antiviral activity of silver, copper, and selenium nanoparticle suspensions in deep eutectic solvent

Metallic and nonmetallic nanoparticles are bioactive compounds that exhibit broad resistance to bacteria, fungi, and even viruses. In this paper, a deep eutectic solvent (DES) based on betaine, glucose, and ethylene glycol was used to obtain suspensions of silver, copper, and selenium nanoparticles. Depending on the nanoparticle precursor used, Ag, Cu, and Se nanoparticles (NPs) with an average particle size of 50–100 nm were prepared, and the properties of the products were confirmed by the STEM, XPS, DLS, and UV–VIS methods. The use of a DES, without the need for additional reactants, allowed the production of stable nanoparticles with increased bioactivity against microorganisms. The obtained systems showed high bioactivity against strains of S. aureus, E. coli, and C. albicans. Nanosuspensions, by generating reactive oxygen species (ROSs), caused enzyme inactivation and the inhibition of the metabolic processes of microorganisms. Particle-generated cell degradation processes were investigated through ROS generation assays, API assays, the determination of the MIC/MBC, and cell decomposition rate assays in the early logarithmic growth phase. Copper nanoparticles derived from copper(II) acetate were also highly active against the human influenza A/H1N1 viruses, human coronavirus (HCoV-OC43, Betacoronavirus 1), and vesicular stomatitis virus (VSV, Rhabdoviridae), showing a virus titer reduction of more than 93.7−99.96%.

Insight into Antiviral Activity of Ag/TiO2 Nanocomposites Against Influenza H1N1 Virus and Its Antiviral Mechanism.

Synthesis and characterization of silver (Ag)/titanium dioxide (TiO2) nanocomposite (ATA) to investigate its antiviral activity against the H1N1 influenza virus and antiviral mechanisms. A water-dispersible ATA was prepared by a photocatalytic reduction process from AgNO3 and TiO2. The characterization of ATA was performed by ultraviolet-visible spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The antiviral activities and the antiviral mechanism of ATA were investigated in detail by light microscopy, transmission electron microscopy and biological techniques such as cell cytotoxicity, 50% tissue culture infectious dose detection, western blot and reverse transcription-polymerase chain reaction. These results showed the successful synthesis of ATA nanocomposite with uniform particle size and distribution. It demonstrated the highly efficient antiviral activity of ATA in a dose- and time-dependent manner, as indicated by the reduction of viral titer and the reduction of cytopathic effects caused by viral infection. In the presence of ATA, the structure of the H1N1 influenza virus is directly destroyed and even disintegrated, with the damaged surface membrane proteins and fuzzy contour. It reduces the infection efficiency of influenza by suppressing the activity and expression of hemagglutinin and neuraminidase. The results of mechanistic studies suggested that ATA nanocomposite primarily interferes with virus attachment to viral receptors on the cell surface. Our study suggests that ATA may be a good antiviral candidate against the influenza virus. Compared with AgNPs alone, our synthesized ATA nanocomposites can achieve similar viral inactivation rates using only a much smaller concentration of AgNPs, greatly reducing the amount of AgNPs and their potential side effects. It has great practical value for attaching ATA to the high-efficiency particulate air network in the air purifier, which can kill the virus attached to it and limit its spread.

Immunogenicity and efficacy of XBB.1.5 rS vaccine against the EG.5.1 variant of SARS-CoV-2 in Syrian hamsters.

As SARS-CoV-2 continues to evolve, there is a need to assess the immunogenicity and efficacy of updated vaccines against newly emerging variants in pre-clinical models such as mice and hamsters. Here, we compared the immunogenicity and efficacy between the updated XBB.1.5, the original Prototype Wuhan-1, and the bivalent Prototype + BA.5 vaccine against a challenge with the EG.5.1 Omicron variant of SARS-CoV-2 in hamsters. The XBB.1.5 and bivalent vaccine, but not the Prototype, induced serum-neutralizing antibodies against EG.5.1, albeit the titers were higher in the XBB.1.5 immunized hamsters. The presence of neutralizing antibodies was associated with complete protection against EG.5.1 infection in the lower airways and reduced virus titers in the upper airways. Compared with the bivalent vaccine, immunization with XBB.1.5 improved viral control in the nasal turbinates. Together, our data show that the updated vaccine is immunogenic and that it offers better protection against recent variants of SARS-CoV-2.

Role of RNA G-Quadruplexes in the Japanese Encephalitis Virus Genome and Their Recognition as Prospective Antiviral Targets.

G-quadruplexes (GQs) have been primarily studied in the context of cancer and neurodegenerative pathologies. However, recent research has shifted focus to their existence and functional roles in viral genomes, revealing GQ-regulated key pathways in various human pathogenic viruses. While GQ structures have been reported in the genomes of emerging and re-emerging viruses, RNA viruses have been understudied compared to DNA viruses, including notable examples such as human immunodeficiency virus-1, hepatitis C virus, Ebola virus, Nipah virus, Zika virus, and SARS-CoV-2. The flavivirus family, comprising the Japanese encephalitis virus (JEV), poses a significant global threat due to recurring outbreaks yet lacks approved antivirals. In this study, we identified and characterized eight putative G-quadruplex-forming motifs within essential genes involved in genome replication, assembly, and internalization in the host cell, conserved across different JEV isolates. The formation and stability of these motifs were validated through a multitude of biophysical and cell-based assays. The interaction and binding affinity of these motifs with the known GQ-binding ligand BRACO-19 were supported by biophysical assays, confirming the capability of these motifs to form GQ structures. Notably, BRACO-19 also exerted antiviral properties through reduction of viral replication and infectious virus titers as well as inhibition of viral protein expression, as evaluated by the cell-based assays. This comprehensive molecular characterization of G-quadruplex structures within the JEV genome highlights their potential as promising antiviral targets for intervention strategies against JEV infection through GQ-specific ligands.

Evaluation of anti-viral photodynamic therapy effects of different concentrations of 5-ALA using light irradiation on HSV-1

BackgroundHerpes simplex virus (HSV) infections are prevalent worldwide, posing challenges due to asymptomatic carriage and recurrent outbreaks. Conventional treatments, including antiviral medications, are limited by drug resistance. Photodynamic therapy (PDT) offers a promising alternative, leveraging photosensitizers to induce viral inactivation via reactive oxygen species (ROS) generation upon light activation. MethodsThis study investigates the efficacy of 5-aminolevulinic acid (5-ALA) as a photosensitizer in antiviral PDT against HSV-1. HSV-1 was treated with varying concentrations of 5-ALA and subjected to light irradiation at a 630 nm wavelength. Virus titers were assessed using the 50 % Tissue Culture Infectious dose (TCID50) assay. Six experimental groups were used: [1] Control (no 5-ALA or light), HSV-1 with 0.05 g/ml 5-ALA and 630 nm light, [2] HSV-1 with 0.05 g/ml 5-ALA (no light), [3] HSV-1 with 0.1 g/ml 5-ALA and light, [4] HSV-1 with 0.1 g/ml 5-ALA (no light), and [5] HSV-1 with light (no 5-ALA). ResultsVirus treatment with 0.1 g/ml 5-ALA combined with light irradiation significantly reduced HSV-1 titer compared to control groups (p < 0.05). Specifically, the virus titer decreased from 10 6.3 TCID50/ml in the control group to 10 4.5 TCID50/ml in the treated group. However, lower concentrations of 5-ALA or light irradiation alone did not yield significant reductions in HSV-1 titer (p > 0.05). Group 4, receiving 0.1 g/ml 5-ALA with light irradiation, exhibited a significantly greater reduction in virus titer than group 2, receiving 0.05 g/ml 5-ALA with light irradiation (p < 0.05). Conclusions5-ALA-mediated PDT demonstrates selective antiviral efficacy against HSV-1, particularly at higher concentrations coupled with light irradiation. These findings underscore the potential of 5-ALA-based PDT as a promising approach for HSV-1 treatment, especially in cases of drug-resistant strains and immunocompromised individuals. Optimization of dosage and treatment protocols is essential for maximizing effectiveness in clinical applications, highlighting the need for further research in this area.

Antiviral activity of povidone-iodine gargle and mouthwash solution against Enterovirus A71, Coxsackieviruses A16, A10 and A6.

Hand, Foot and Mouth Disease (HFMD), a highly contagious viral disease common among infants and young children, is primarily caused by Enterovirus A71 (EV-A71) and Coxsackievirus A16 (CVA16). Nonetheless, emerging enteroviruses, such as CV-A10 and CV-A6, have also caused widespread outbreaks globally, in part due to the absence of effective antiviral therapies, and the high personto-person transmission rate. Person-to-person transmission is usually through fecal-oral or oral-oral routes, and sometimes via droplets. As the oral cavity is a primary site for early virus infection and replication, controlling oral viral shedding can mitigate the risk of transmission through this route. Povidone-iodine (PVP-I), a widely used antiseptic, has shown broad-spectrum antimicrobial properties but antiviral studies against HFMD-causing enteroviruses are limited, especially for CV-A10 and CVA6. Our study demonstrated that a 1% PVP-I solution (final concentration of 0.5%) exhibited virucidal activity against EV-A71, CV-A16, CV-A10, and CV-A6. All seven EV-A71 isolates and five CV-A16 isolates showed a significant virus titer reduction after a 1-minute incubation, while five CV-A10 isolates and two CV-A6 isolates required a 5-minute incubation to achieve this. The virucidal activity was confirmed through the EN14476:2013+A2:2019 virucidal quantitative suspension test, wherein all four viruses were completely inactivated after a 30-minute incubation with PVP-I at 37°C under both clean and dirty conditions. Western blot analysis suggested that PVP-I could affect the VP1 structural proteins of EV-A71. Our results suggest that PVP-I could serve as a potential virucidal agent to reduce the risk of person-to-person transmission of HFMD.

Antiviral activity of Nigella sativa oil against two SARS-CoV-2surrogates in vitro as a dietary product

Background: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is primarily transmitted via aerosol and droplets, but environmental surfaces or potentially contaminated foods may contribute to further viral transmission. Nigella sativa seed (black cumin seed) oil possesses various biological activities against bacteria, fungi, parasites, orviruses. Objectives: This study aimed to explore black cumin seed oil (BSO) with anti-SARS-CoV-2 activities using bovine coronavirus (BCoV) and human coronavirus (HCoV) OC43 as surrogates. Methods and Results: BSO was tested at 1-100 mL/L concentrations for cytotoxicity towards human rectal tumor (HRT-18G) cells and 0.1-10 mL/L for efficacy against BCoV and HCoV OC43 in suspension. Two coronaviruses were separately mixed with BSO suspension and incubated for various times (0, 15, 30, 45, and 60 min) at 4, 23, and 37°C. The virus titerreduction was determined by median tissue culture infectious dose (TCID50) assay with HRT-18G cells as the host. BSO concentrations of 1-20 mL/L exhibited low cytotoxicity (&lt;10%) towards HRT-18G cells. The inactivation of coronaviruses by BSO was concentration-, temperature-, and exposure time-dependent. At 37°C, BSO reduced 2.0 logs of BCoV and3.0 logs of HCoV OC43 in 60 min, respectively. Specifically, half maximal effective concentration (EC50) of BSO at 4, 23, and 37°C after the 1-h exposure was 4.28, 3.06, and 0.87 mL/L against BCoV, respectively, and 0.61, 0.61 and 0.48 mL/L against HCoV OC43, respectively. Moreover, BSO didn’t affect the attachment of BCoV and HCoV OC43 into host cells. Conclusion: Our findings on the inhibition activity of BSO against SARS-CoV-2 surrogates suggested the potential use of this natural product in mitigating SARS-CoV-2 infection. Our results also suggest that HCoV OC43 may be a more appropriate surrogate for SARS-CoV-2 to screen antiviral dietary products. Keywords: Nigella sativa, SARS-CoV-2 surrogates, antiviral activity, quantitative suspension test, dietary supplement

Inhibition of SARS-CoV-2 growth in the lungs of mice by a peptide-conjugated morpholino oligomer targeting viral RNA

Further development of direct-acting antiviral agents against human SARS-CoV-2 infections remains a public health priority. Here, we report that an antisense peptide-conjugated morpholino oligomer (PPMO), named 5’END-2, targeting a highly conserved sequence in the 5’UTR of SARS-CoV-2 genomic RNA, potently suppressed SARS-CoV-2 growth in vitro and in vivo. In Hela-ACE 2 cells, 5’END-2 produced IC50 values of between 40 nM and 1.15 μM in challenges using six genetically disparate strains of SARS-CoV-2, including JN.1. In vivo, using K18-hACE2 mice and the WA-1/2020 virus isolate, two doses of 5’END-2 at 10 mg/kg, administered intranasally on the day before and the day after infection, produced approximately 1.4 log10 virus titer reduction in lung tissue at 3 days post-infection. Under a similar dosing schedule, intratracheal administration of 1.0 to 2.0 mg/kg 5’END-2 produced over 3.5 log10 virus growth suppression in mouse lungs. Electrophoretic mobility shift assays characterized specific binding of 5’END-2 to its complementary target RNA. Further, using reporter constructs containing SARS-CoV-2 5’UTR leader sequence, in an in-cell system, we observed that 5’END-2 could interfere with translation in a sequence-specific manner. The results demonstrate that direct pulmonary delivery of 5’END-2 PPMO is a promising antiviral strategy against SARS-CoV-2 infections and warrants further development.

Antiviral Activity of Graphene Oxide-Silver Nanocomposites Against Murine Betacoronavirus.

The high infectivity of coronaviruses has led to increased interest in developing new strategies to prevent virus spread. Silver nanoparticles (AgNPs) and graphene oxide (GO) have attracted much attention in the antiviral field. We investigated the potential antiviral activity of GO and AgNPs combined in the nanocomposite GO-Ag against murine betacoronavirus MHV using an in vitro model. GO, AgNPs, and GO-Ag characterization (size distribution, zeta potential, TEM visualization, FT-IR, and EDX analysis) and XTT assay were performed. The antiviral activity of GO-Ag nanocomposites was evaluated by RT-qPCR and TCID50 assays. The results were compared with free AgNPs and pure GO. Cell growth and morphology of MHV-infected hepatocytes treated with GO-Ag composites were analyzed by JuLI™Br. Immunofluorescence was used to visualize the cell receptor used by MHV. Ultrastructural SEM analysis was performed to examine cell morphology after MHV infection and GO-Ag composite treatment. A significant reduction in virus titer was observed for all nanocomposites tested, ranging from 3.2 to 7.3 log10 TCID50. The highest titer reduction was obtained for GO 5 µg/mL - Ag 25 µg/mL in the post-treatment method. These results were confirmed by RT-qPCR analysis. The results indicate that GO-Ag nanocomposites exhibited better antiviral activity compared to AgNPs and GO. Moreover, the attachment of AgNPs to the GO flake platform reduced their cytotoxicity. In addition, the GO-Ag composite modulates the distribution of the Ceacam1 cell receptor and can modulate cell morphology. Graphene oxide sheets act as a stabilizing agent, inhibiting the accumulation of AgNPs and reducing their cellular toxicity. The GO-Ag composite can physically bind and inhibit murine betacoronavirus from entering cells. Furthermore, the constant presence of GO-Ag can inhibit MHV replication and significantly limit its extracellular release. In conclusion, GO-Ag shows promise as an antiviral coating on solid surfaces to minimize virus transmission and spread.

Exacerbation of influenza virus induced lung injury by alveolar macrophages and its suppression by pyroptosis blockade in a human lung alveolus chip.

Alveolar macrophages (AMs) are the major sentinel immune cells in human alveoli and play a central role in eliciting host inflammatory responses upon distal lung viral infection. Here, we incorporated peripheral human monocyte-derived macrophages within a microfluidic human Lung Alveolus Chip that recreates the human alveolar-capillary interface under an air-liquid interface along with vascular flow to study how residential AMs contribute to the human pulmonary response to viral infection. When Lung Alveolus Chips that were cultured with macrophages were infected with influenza H3N2, there was a major reduction in viral titers compared to chips without macrophages; however, there was significantly greater inflammation and tissue injury. Pro-inflammatory cytokine levels, recruitment of immune cells circulating through the vascular channel, and expression of genes involved in myelocyte activation were all increased, and this was accompanied by reduced epithelial and endothelial cell viability and compromise of the alveolar tissue barrier. These effects were partially mediated through activation of pyroptosis in macrophages and release of pro-inflammatory mediators, such as interleukin (IL)-1β, and blocking pyroptosis via caspase-1 inhibition suppressed lung inflammation and injury on-chip. These findings demonstrate how integrating tissue resident immune cells within human Lung Alveolus Chip can identify potential new therapeutic targets and uncover cell and molecular mechanisms that contribute to the development of viral pneumonia and acute respiratory distress syndrome (ARDS).

Mucosal immunization with ChAd-SARS-CoV-2-S prevents sequential transmission of SARS-CoV-2 to unvaccinated hamsters.

COVID-19 vaccines have successfully reduced severe disease and death after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Nonetheless, COVID-19 vaccines are variably effective in preventing transmission and symptomatic SARS-CoV-2 infection. Here, we evaluated the impact of mucosal or intramuscular vaccine immunization on airborne infection and transmission of SARS-CoV-2 in Syrian hamsters. Immunization of the primary contact hamsters with a mucosal chimpanzee adenoviral-vectored vaccine (ChAd-CoV-2-S), but not intramuscular messenger RNA (mRNA) vaccine, reduced infectious virus titers ~100-fold and 100,000-fold in the upper and lower respiratory tract of the primary contact hamster following SARS-CoV-2 exposure. This reduction in virus titer in the mucosal immunized contact animals was sufficient to eliminate subsequent transmission to vaccinated and unvaccinated hamsters. In contrast, sequential transmission occurred after systemic immunization with the mRNA vaccine. Thus, immunization with a mucosal COVID-19 vaccine protects against cycles of respiratory transmission of SARS-CoV-2 and can potentially limit the community spread of the virus.

SILAR deposited Antiviral silver-doped Ceria nano-films

Amid the COVID-19 global pandemic, ceria nanomaterials (CN) have garnered renewed interest as potential antiviral agents due to their ability to generate reactive oxygen species (ROS) on their surfaces. Enhancing ROS generation through precise defect engineering is key to improving these antiviral properties. This can be achieved through various methods, such as altering nano-dimensions and doping. In this context, we report on silver-doped ceria thin films. We have employed a cost-effective SILAR (Successive Ionic Layer Adsorption and Reaction) method for ceria nano-film deposition, which offers excellent control over film thickness. Utilizing an Arduino-controlled layer-by-layer (LBL) setup, we achieved precise control over the deposition process. This method facilitated the easy doping of ceria nano-films with silver ions. The silver-doped SILAR ceria thin films of varying thicknesses were subjected to antibacterial testing against E. coli bacteria. The samples with the highest antibacterial activity were further tested for antiviral efficacy against Feline calicivirus. The 80 SILAR Layers Ag-Ceria sample exhibited the best activity, completely deactivating the viral titer (105). This sample, when further tested against OC43 coronavirus, demonstrated a >99% reduction in virus titer. The mechanisms underlying these antimicrobial properties were investigated using antioxidative testing assays.

Exploring the potency of polyphenol-rich blend from Lonicera caerulea var. Kamtschatica sevast., Aronia melanocarpa, and Echinacea purpurea: Promising anti-inflammatory, antioxidant, and antiviral properties

Previous studies have highlighted the beneficial properties of plants rich in polyphenols, such as Lonicera caerulea var. Kamtschatica Sevast. (LCK), Aronia melanocarpa (AM), and Echinacea purpurea (EP). These plants have demonstrated antioxidant, immunomodulatory, and potential antiviral effects. Thus, the objective of this study was to investigate the impact of the ELA blend, a polyphenol-rich blend containing EP, LCK, and AM, on the cellular mechanisms involved in viral infection. To assess the effects of the ELA blend, various experiments were conducted using A549 cells and a mucociliary tissue 3D model called EpiAirway™. Inflammation and oxidative stress induced by LPS were evaluated through measurements of SOD activity, ELISA, and qPCR analysis. Additionally, antiviral assays were performed in a cell-present environment to examine the blend's effectiveness against HCoV-OC43. The results showed that the ELA blend-treated group exhibited reduced expression of IL1B, CXCL8, ICAM1, MCP1, and RELA in both A549 cells and EpiAirway™. Moreover, the blend enhanced the expression of CAT, HMOX1, SOD1, and SOD2 in A549 cells. The antiviral activity of the ELA blend was also investigated, i.e. its influence on viral replication cycle, to determine the potential as an antiviral preparation. At the highest non-cytotoxic concentration, the ELA blend demonstrated a 87.5 % reduction in viral titer when administered simultaneously with HCoV-OC43. It emphasize potential ability of the preparation to block viral entry to the host cells. At the same time, ELA blend did not express virucidal activity, i.e. inactivation of free viral particles, against HCoV-OC43. In conclusion, ELA blend displayed antiviral activity and exhibited immunomodulatory and antioxidant effects. Based on these findings, it can be concluded that ELA blend has potential for the prevention and treatment of viral infections.