Virus-induced Oxidative Stress Research Articles

Tripartite interactions between grapevine, viruses, and arbuscular mycorrhizal fungi provide insights into modulation of oxidative stress responses

Arbuscular mycorrhizal fungi (AMF) can be beneficial for plants exposed to abiotic and biotic stressors. Although widely present in agroecosystems, AMF influence on crop responses to virus infection is underexplored, particularly in woody plant species such as grapevine. Here, a two-year greenhouse experiment was set up to test the hypothesis that AMF alleviate virus-induced oxidative stress in grapevine. The ‘Merlot’ cultivar was infected with three grapevine-associated viruses and subsequently colonized with two AMF inocula, containing one or three species, respectively. Five and fifteen months after AMF inoculation, lipid peroxidation - LPO as an indicator of oxidative stress and indicators of antioxidative response (proline, ascorbate - AsA, superoxide dismutase - SOD, ascorbate- APX and guaiacol peroxidases - GPOD, polyphenol oxidase - PPO, glutathione reductase - GR) were analysed. Expression of genes coding for a stilbene synthase (STS1), an enhanced disease susceptibility (EDS1) and a lipoxygenase (LOX) were determined in the second harvesting. AMF induced reduction of AsA and SOD over both years, which, combined with not AMF-triggered APX and GR, suggests decreased activation of the ascorbate-glutathione cycle. In the mature phase of the AM symbiosis establishment GPOD emerged as an important mechanism for scavenging H2O2 accumulation. These results, together with reduction in STS1 and increase in EDS1 gene expression, suggest more efficient reactive oxygen species scavenging in plants inoculated with AMF. Composition of AMF inocula was important for proline accumulation. Overall, our study improves the knowledge on ubiquitous grapevine-virus-AMF systems in the field, highlighting that established functional AM symbiosis could reduce virus-induced stress.

Physiological and Biochemical Responses Induced by Plum Pox Virus and Plum Bark Necrosis Steam Pitting Associated Virus in Tuscany Autochthonous Plum cv. Coscia di Monaca.

The present study focused on trees of Tuscany autochthonous plum cv. Coscia di Monaca in order to evaluate the presence of viruses and elucidate the physiological and biochemical responses to virus infections under real field conditions. Among the several investigated viruses, plums tested positive only to plum pox virus (PPV) and plum bark necrosis steam pitting associated virus (PBNSPaV), occurring as both singular and co-infections. This is the first report of PBNSPaV in a Tuscany orchard. Furthermore, the present study not only confirmed the detrimental effects of PPV on the carbon dioxide assimilation rate due to both stomatal limitations and mesophyll impairments, but also showed that although PBNSPaV did not induce such photosynthetic impairments when occurring as singular infection, it enhanced this damaging effect when present as a co-infection with PPV, as confirmed by a severe decrease in the chlorophyll content. Infection-specific responses in terms of accessory pigments (i.e., carotenoids and xanthophylls), as well as sugars and organic acids, were also reported, these being likely related to photoprotective mechanisms and osmotic regulations under virus-induced oxidative stress. Overall, the results here presented represent an important step to fill knowledge gaps about the interaction of plant viruses and autochthonous Prunus cultivars.

Carambolaside W Inhibited H1N1 Influenza Virus-Induced Oxidative Stress through STAT-3/BCL-XL Signaling Pathway.

The H1N1 influenza virus is highly infectious and pathogenic, and in recent years, it has often presented seasonal mass outbreaks of infection. People infected with H1N1 will develop a high fever and other respiratory infection symptoms. If not treated in time, complications such as pneumonia may occur. In this study, we focused on developing drugs that can effectively fight against with H1N1 virus. A flavonoid glycoside was extracted from the carambola, then characterized by HR-ESI-MS with the molecular formula C47H58O2, and named carambolaside W. The flavonoid glycosides were found to have good anti-H1N1 influenza virus effects. In this study, we verified that carambolaside W has low toxicity and can effectively inhibit influenza virus replication in vitro. H1N1 virus infection induces intracellular oxidative stress damage to accelerate disease progression. The results showed that carambolaside W effectively inhibited the oxidative stress caused by H1N1 infection. The Western blot assay also revealed that carambolaside W alters the expression of apoptosis-related proteins in vitro and exerts a good anti-H1N1 influenza virus effect. In summary, carambolaside W is a low-toxicity natural flavonoid that can effectively treat the H1N1 influenza virus as a potential anti-H1N1 virus agent.

Sirtuin3 Alleviated Influenza A Virus-Induced Mitochondrial Oxidative Stress and Inflammation in Lung Epithelial Cells via Regulating Poly (ADP-Ribose) Polymerase 1 Activity

Introduction: Influenza A virus (IAV) infection causes severe lung inflammation and injury, particularly in children. Sirtuin3 (Sirt3) was confirmed to be effective in protecting the lung against injury. This study aims to explore the function and mechanism of Sirt3 on influenza development in children. Methods: The Sirt3 level in serum samples from IAV-infected children and lung epithelial cells were detected using RT-qPCR, ELISA, and Western blot assays. Cell viability and apoptosis were determined by MTT and flow cytometry assays. Virus titration was conducted by determining TCID₅₀. Cell inflammatory response was detected by a battery of inflammatory cytokines. The contents of ROS and ATP, mitochondrial membrane potential level, and oxygen-consumption rate were examined to reflect on oxidative stress and mitochondrial dysfunction. The activity of poly (ADP-ribose) polymerase 1 (PARP-1) was measured by colorimetry. Results: Sirt3 was downregulated in IAV-infected children’s serum samples and BEAS-2B cells. Overexpression of Sirt3 alleviated IAV replication and IAV-induced inflammatory injury, oxidative stress, and mitochondrial dysfunction in lung epithelial cells. Moreover, upregulation of Sirt3 deacetylated SOD2 and PARP-1 and inhibited the PARP-1 activity. Notably, the Sirt3 inhibitor (3-TYP) and PARP-1 activity agonist (nicotinamide) reversed the effects of Sirt3 overexpression on IAV replication and IAV-induced injury. Conclusion: Overexpression of Sirt3 attenuated IAV-evoked inflammatory injury and mitochondrial oxidative stress through the inhibition of PARP-1 activity in lung epithelial cells.

Vitisin B inhibits influenza A virus replication by multi-targeting neuraminidase and virus-induced oxidative stress.

The development of drug-resistant influenza and new pathogenic virus strains underscores the need for antiviral therapeutics. Currently, neuraminidase (NA) inhibitors are commonly used antiviral drugs approved by the US Food and Drug Administration (FDA) for the prevention and treatment of influenza. Here, we show that vitisin B (VB) inhibits NA activity and suppresses H1N1 viral replication in MDCK and A549 cells. Reactive oxygen species (ROS), which frequently occur during viral infection, increase virus replication by activating the NF-κB signaling pathway, downmodulating glucose-6-phosphate dehydrogenase (G6PD) expression, and decreasing the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant response activity. VB decreased virus-induced ROS generation by increasing G6PD expression and Nrf2 activity, and inhibiting NF-κB translocation to the nucleus through IKK dephosphorylation. In addition, VB reduced body weight loss, increased survival, decreased viral replication and the inflammatory response in the lungs of influenza A virus (IAV)-infected mice. Taken together, our results indicate that VB is a promising therapeutic candidate against IAV infection, complements existing drug limitations targeting viral NA. It modulated the intracellular ROS by G6PD, Nrf2 antioxidant response pathway, and NF-κB signaling pathway. These results demonstrate the feasibility of a multi-targeting drug strategy, providing new approaches for drug discovery against IAV infection.

Epstein-Barr virus infection controls the concentration of the intracellular antioxidant glutathione by upregulation of the glutamate transporter EAAT3 in tumor cells.

Epstein-Barr virus or human herpesvirus 4 (EBV/HHV-4) is an omnipresent oncovirus etiologically associated with various B-cell lymphomas and epithelial cancers. The malignant transformation associated with the persistent expression of viral proteins often deregulates the host cellular machinery and EBV infection is coupled to elevated levels of reactive oxygen species. Here, we investigated the role that the glutamate transporter EAAT3 plays in regulating the antioxidant system as a protective mechanism of EBV-infected cells against the virus-induced oxidative stress. Our study demonstrated that the expression of EAAT3 was upregulated and localized to the plasma membrane in EBV latently infected and de novo EBV-infected cells. EAAT3 was regulated by the transcription factor NFAT5 in the infected cells. Membrane localized EAAT3 was found to be involved in the transportation of glutamate from the extracellular space into the cell, as EAAT3 and NFAT5 inhibitors markedly reduced the levels of intracellular glutamate levels in EBV latently infected cells. Additionally, our data demonstrated a notable decrease in the intracellular glutathione levels following treatment with an EAAT3 inhibitor. Collectively, our results suggest that upregulation of the glutamate transporter EAAT3 is an adaptation of EBV-infected cells to maintain cellular redox homeostasis against the virus-induced oxidative stress, and that this cellular balance could be therapeutically destroyed by targeting EAAT3 to impede EBV-associated cancers.

Mechanism of Multi-Organ Injury in Experimental COVID-19 and Its Inhibition by a Small Molecule Peptide.

Severe disease from SARS-CoV-2 infection often progresses to multi-organ failure and results in an increased mortality rate amongst these patients. However, underlying mechanisms of SARS- CoV-2-induced multi-organ failure and subsequent death are still largely unknown. Cytokine storm, increased levels of inflammatory mediators, endothelial dysfunction, coagulation abnormalities, and infiltration of inflammatory cells into the organs contribute to the pathogenesis of COVID-19. One potential consequence of immune/inflammatory events is the acute progression of generalized edema, which may lead to death. We, therefore, examined the involvement of water channels in the development of edema in multiple organs and their contribution to organ dysfunction in a Murine Hepatitis Virus-1 (MHV-1) mouse model of COVID-19. Using this model, we recently reported multi-organ pathological abnormalities and animal death similar to that reported in humans with SARS-CoV-2 infection. We now identified an alteration in protein levels of AQPs 1, 4, 5, and 8 and associated oxidative stress, along with various degrees of tissue edema in multiple organs, which correlate well with animal survival post-MHV-1 infection. Furthermore, our newly created drug (a 15 amino acid synthetic peptide, known as SPIKENET) that was designed to prevent the binding of spike glycoproteins with their receptor(s), angiotensin- converting enzyme 2 (ACE2), and carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) (SARS-CoV-2 and MHV-1, respectively), ameliorated animal death and reversed altered levels of AQPs and oxidative stress post-MHV-1 infection. Collectively, our findings suggest the possible involvement of altered aquaporins and the subsequent edema, likely mediated by the virus-induced inflammatory and oxidative stress response, in the pathogenesis of COVID- 19 and the potential of SPIKENET as a therapeutic option.

Infection of Endothelial Cells by Dengue Virus Induces ROS Production by Different Sources Affecting Virus Replication, Cellular Activation, Death and Vascular Permeability.

Exacerbated inflammatory response and altered vascular function are hallmarks of dengue disease. Reactive oxygen species (ROS) production has been associated to endothelial barrier disturbance and microvascular alteration in distinct pathological conditions. Increased ROS has been reported in in vitro models of dengue virus (DENV) infection, but its impact for endothelial cell physiology had not been fully investigated. Our group had previously demonstrated that infection of human brain microvascular endothelial cells (HBMEC) with DENV results in the activation of RNA sensors and production of proinflammatory cytokines, which culminate in cell death and endothelial permeability. Here, we evaluated the role of mitochondrial function and NADPH oxidase (NOX) activation for ROS generation in HBMEC infected by DENV and investigated whether altered cellular physiology could be a consequence of virus-induced oxidative stress. DENV-infected HBMECs showed a decrease in the maximal respiratory capacity and altered membrane potential, indicating functional mitochondrial alteration, what might be related to mtROS production. Indeed, mtROS was detected at later time points after infection. Specific inhibition of mtROS diminished virus replication, cell death, and endothelial permeability, but did not affect cytokine production. On the other hand, inhibition of NOX-associated ROS production decreased virus replication and cell death, as well as the secretion of inflammatory cytokines, including IL-6, IL-8, and CCL5. These results demonstrated that DENV replication in endothelial cells induces ROS production by different pathways, which impacts biological functions that might be relevant for dengue pathogenesis. Those data also indicate oxidative stress events as relevant therapeutical targets to avoid vascular permeability, inflammation, and neuroinvasion during DENV infection.

Heparanase-1 is upregulated by hepatitis C virus and favors its replication

Over time, chronic HCV infection can lead to hepatocellular carcinoma (HCC), a process that involves changes to the liver extracellular matrix (ECM). However, the exact mechanisms by which HCV induces HCC remain unclear. Therefore, we sought to investigate the impact of HCV on the liver ECM, with a focus on heparanase-1 (HPSE). HPSE expression was assessed by quantitative reverse-transcription PCR, immunoblotting and immunofluorescence in liver biopsies infected or not with HCV, and in 10-day-infected hepatoma Huh7.5 cells. Cell lines deficient for or overexpressing HPSE were established to study its role during infection. HCV propagation led to significant HPSE induction, invivo and invitro. HPSE enhanced infection when exogenously expressed or supplemented as a recombinant protein. Conversely, when HPSE expression was downregulated or its activity blocked, HCV infection dropped, suggesting a role of HPSE in the HCV life cycle. We further studied the underlying mechanisms of such observations and found that HPSE favored HCV release by enhancing CD63 synthesis and exosome secretion, but not by stimulating HCV entry or genome replication. We also showed that virus-induced oxidative stress was involved in HPSE induction, most likely through NF-κB activation. We report for the first time that HCV infection is favored by HPSE, and upregulates HPSE expression and secretion, which may result in pathogenic alterations of the ECM. Chronic hepatitis C virus (HCV) infection can lead to hepatocellular carcinoma development in a process that involves derangement of the extracellular matrix (ECM). Herein, we show that heparanase-1, a protein involved in ECM degradation and remodeling, favors HCV infection and is upregulated by HCV infection; this upregulation may result in pathogenic alterations of the ECM.

Use of Nuclear Factor Erythroid 2-Eelated Factor Activators as A Strategy to Improve the Side Effects of COVID-19

Coronavirus disease-19 (COVID-19) is a new member of the coronavirus family causing acute respiratory infection. Patients with COVID-19 have a higher risk of developing oxidative stress during this infection. Moreover, the virus induces ROS production that activates cellular pathways for viral replication. Nuclear factor erythroid 2-related factor (Nrf2) is a crucial transcription factor in cellular antioxidant defense by mediating Virus-induced oxidative stress and ROS production. This article suggests that an Nrf2 activator may be beneficial in preventing oxidative stress development in COVID-19 patients. Coronaviruses are a significant group of viruses that cause different illnesses in humans and animals. These illnesses can range from the common cold to more severe diseases such as SARS (Severe acute respiratory syndrome), Middle East Respiratory Syndrome (MERS), and COVID-19. COVID-19 is a new viral disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The main symptoms of COVID-19-infected patients are fever, dry cough, fatigue, and sometimes respiratory problems such as shortness of breath, sore throat, and infection [1].

The Role of Tricarboxylic Acid Cycle Metabolites in Viral Infections.

Host cell metabolism is essential for the viral replication cycle and, therefore, for productive infection. Energy (ATP) is required for the receptor-mediated attachment of viral particles to susceptible cells and for their entry into the cytoplasm. Host cells must synthesize an array of biomolecules and engage in intracellular trafficking processes to enable viruses to complete their replication cycle. The tricarboxylic acid (TCA) cycle has a key role in ATP production as well as in the synthesis of the biomolecules needed for viral replication. The final assembly and budding process of enveloped viruses, for instance, require lipids, and the TCA cycle provides the precursor (citrate) for fatty acid synthesis (FAS). Viral infections may induce host inflammation and TCA cycle metabolic intermediates participate in this process, notably citrate and succinate. On the other hand, viral infections may promote the synthesis of itaconate from TCA cis-aconitate. Itaconate harbors anti-inflammatory, anti-oxidant, and anti-microbial properties. Fumarate is another TCA cycle intermediate with immunoregulatory properties, and its derivatives such as dimethyl fumarate (DMF) are therapeutic candidates for the contention of virus-induced hyper-inflammation and oxidative stress. The TCA cycle is at the core of viral infection and replication as well as viral pathogenesis and anti-viral immunity. This review highlights the role of the TCA cycle in viral infections and explores recent advances in the fast-moving field of virometabolism.

English

Currently, the human being faces a contagious virus called SARS-CoV-2 with a high transmission ability, infection, and a relatively high mortality rate, especially for the elderly. All research interest is directed to finding a drug or vaccine to save millions of people’s lives; some have succeeded and applied now in some countries. Medicinal plants represent a green treasure that renders plentiful primary and secondary metabolites characterized by potent biological activities. Interestingly, the secondary metabolites, alkaloids, flavonoids, tannins, and terpenoids, own a broad antiviral history. The plant antiviral capabilities may be due to inhibition of viral attachment to/penetration of the host cell; inhibition of the virus replication; suppressing RNA replication; downregulation of viral proteins translation; interfering with virus non-structural/structural protein; downregulation of virus-induced pro-inflammatory/inflammatory signaling pathways in the host cell, and antioxidant activity thus abating the virus-induced oxidative stress effect. Presently, as we are trapped with a surly virus, there are attempts to exploit the power of nature. Therefore, this review’s main objective is to refer to some medicinal plants or their derivatives that limit the virus’s virulence or alleviate the symptoms associated with this virus. Key words: SARS-CoV-2, medicinal plants, natural extracts, flavonoids, alkaloids, antiviral.

Peroxiredoxins-The Underrated Actors during Virus-Induced Oxidative Stress.

Enhanced production of reactive oxygen species (ROS) triggered by various stimuli, including viral infections, has attributed much attention in the past years. It has been shown that different viruses that cause acute or chronic diseases induce oxidative stress in infected cells and dysregulate antioxidant its antioxidant capacity. However, most studies focused on catalase and superoxide dismutases, whereas a family of peroxiredoxins (Prdx), the most effective peroxide scavengers, were given little or no attention. In the current review, we demonstrate that peroxiredoxins scavenge hydrogen and organic peroxides at their physiological concentrations at various cell compartments, unlike many other antioxidant enzymes, and discuss their recycling. We also provide data on the regulation of their expression by various transcription factors, as they can be compared with the imprint of viruses on transcriptional machinery. Next, we discuss the involvement of peroxiredoxins in transferring signals from ROS on specific proteins by promoting the oxidation of target cysteine groups, as well as briefly demonstrate evidence of nonenzymatic, chaperone, functions of Prdx. Finally, we give an account of the current state of research of peroxiredoxins for various viruses. These data clearly show that Prdx have not been given proper attention despite all the achievements in general redox biology.

Autophagy is involved in the replication of H9N2 influenza virus via the regulation of oxidative stress in alveolar epithelial cells

BackgroundOxidative stress is an important pathogenic factor in influenza A virus infection. It has been found that reactive oxygen species induced by the H9N2 influenza virus is associated with viral replication. However, the mechanisms involved remain to be elucidated.MethodsIn this study, the role of autophagy was investigated in H9N2 influenza virus-induced oxidative stress and viral replication in A549 cells. Autophagy induced by H9N2 was inhibited by an autophagy inhibitor or RNA interference, the autophagy level, viral replication and the presence of oxidative stress were detected by western blot, TCID50 assay, and Real-time PCR. Then autophagy and oxidative stress were regulated, and viral replication was determined. At last, the Akt/TSC2/mTOR signaling pathways was detected by western blot.ResultsAutophagy was induced by the H9N2 influenza virus and the inhibition of autophagy reduced the viral titer and the expression of nucleoprotein and matrix protein. The blockage of autophagy suppressed the H9N2 virus-induced increase in the presence of oxidative stress, as evidenced by decreased reactive oxygen species production and malonaldehyde generation, and increased superoxide dismutase 1 levels. The changes in the viral titer and NP mRNA level caused by the antioxidant, N-acetyl-cysteine (NAC), and the oxidizing agent, H2O2, confirmed the involvement of oxidative stress in the control of viral replication. NAC plus transfection with Atg5 siRNA significantly reduced the viral titer and oxidative stress compared with NAC treatment alone, which confirmed that autophagy was involved in the replication of H9N2 influenza virus by regulating oxidative stress. Our data also revealed that autophagy was induced by the H9N2 influenza virus through the Akt/TSC2/mTOR pathway. The activation of Akt or the inhibition of TSC2 suppressed the H9N2 virus-induced increase in the level of LC3-II, restored the decrease in the expression of phospho-pAkt, phospho-mTOR and phospho-pS6 caused by H9N2 infection, suppressed the H9N2-induced increase in the presence of oxidative stress, and resulted in a decrease in the viral titer.ConclusionAutophagy is involved in H9N2 virus replication by regulating oxidative stress via the Akt/TSC2/mTOR signaling pathway. Thus, autophagy maybe a target which may be used to improve antiviral therapeutics.

Flavonoids Activation of the Transcription Factor Nrf2 as a Hypothesis Approach for the Prevention and Modulation of SARS-CoV-2 Infection Severity.

The Nrf2-Keap1-ARE pathway is the principal regulator of antioxidant and phase II detoxification genes. Its activation increases the expression of antioxidant and cytoprotective proteins, protecting cells against infections. Nrf2 modulates virus-induced oxidative stress, ROS generation, and disease pathogenesis, which are vital in the viral life cycle. During respiratory viral infections, such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), an inflammatory process, and oxidative stress of the epithelium lining cells activate the transcription factor Nrf2, which protects cells from oxidative stress and inflammation. Nrf2 reduces angiotensin-converting enzyme 2 (ACE2) receptors expression in respiratory epithelial cells. SARS-CoV2 has a high affinity for ACE2 that works as receptors for coronavirus surface spike glycoprotein, facilitating viral entry. Disease severity may also be modulated by pre-existing conditions, such as impaired immune response, obesity, and age, where decreased level of Nrf2 is a common feature. Consequently, Nrf2 activators may increase Nrf2 levels and enhance antiviral mediators’ expression, which could initiate an “antiviral state”, priming cells against viral infection. Therefore, this hypothesis paper describes the use of flavonoid supplements combined with vitamin D3 to activate Nrf2, which may be a potential target to prevent and/or decrease SARS-CoV-2 infection severity, reducing oxidative stress and inflammation, enhancing innate immunity, and downregulating ACE2 receptors.

Hydrogen peroxide and viral infections: A literature review with research hypothesis definition in relation to the current covid-19 pandemic

We reviewed the literature concerning the innate response from nasal and oral epithelial cells and their reaction to hydrogen peroxide (H2O2). Hydrogen peroxide is produced physiologically by oral bacteria and plays a significant role in the balance of oral microecology since it is an important antimicrobial agent. In the epithelial cells, the enzyme superoxide dismutase catalyzes a reaction leading from hydrogen peroxide to the ion superoxide. The induced oxidative stress stimulates a local innate response via activation of the toll-like receptors and the NF-κB. Those kinds of reactions are also activated by viral infections. Virus-induced oxidative stress plays an important role in the regulation of the host immune system and the specific oxidant-sensitive pathway is one of the effective strategies against viral infections. Therefore, nose/mouth/throat washing with hydrogen peroxide may enhance those local innate responses to viral infections and help protect against the current coronavirus pandemic. We strongly encourage the rapid development of randomized controlled trials in both SARS-CoV-2 positive and negative subjects to test the preliminary findings from the in-vitro and in-vivo observational studies that we identified.

Respiratory Syncytial Virus-Induced Oxidative Stress Leads to an Increase in Labile Zinc Pools in Lung Epithelial Cells.

Zinc supplementation in cell culture has been shown to inhibit various viruses, like herpes simplex virus, rotavirus, severe acute respiratory syndrome (SARS) coronavirus, rhinovirus, and respiratory syncytial virus (RSV). However, whether zinc plays a direct antiviral role in viral infections and whether viruses have adopted strategies to modulate zinc homeostasis have not been investigated. Results from clinical trials of zinc supplementation in infections indicate that zinc supplementation may be beneficial in a pathogen- or disease-specific manner, further underscoring the importance of understanding the interaction between zinc homeostasis and virus infections at the molecular level. We investigated the effect of RSV infection on zinc homeostasis and show that RSV infection in lung epithelial cells leads to modulation of zinc homeostasis. The intracellular labile zinc pool increases upon RSV infection in a multiplicity of infection (MOI)-dependent fashion. Small interfering RNA (siRNA)-mediated knockdown of the ubiquitous zinc uptake transporter ZIP1 suggests that labile zinc levels are increased due to the increased uptake by RSV-infected cells as an antiviral response. Adding zinc to culture medium after RSV infection led to significant inhibition of RSV titers, whereas depletion of zinc by a zinc chelator, N,N,N',N'-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN) led to an increase in RSV titers. The inhibitory effect of zinc was specific, as other divalent cations had no effect on RSV titers. Both RSV infection and zinc chelation by TPEN led to reactive oxygen species (ROS) induction, whereas addition of zinc blocked ROS induction. These results suggest a molecular link between RSV infection, zinc homeostasis, and oxidative-stress pathways and provide new insights for developing strategies to counter RSV infection.IMPORTANCE Zinc deficiency rates in developing countries range from 20 to 30%, and zinc supplementation trials have been shown to correct clinical manifestations attributed to zinc deficiency, but the outcomes in the case of respiratory infections have been inconsistent. We aimed at understanding the role of zinc homeostasis in respiratory syncytial virus (RSV) infection. Infection of lung epithelial cell lines or primary small-airway epithelial cells led to an increase in labile zinc pools, which was due to increased uptake of zinc. Zinc supplementation inhibited RSV replication, whereas zinc chelation had an opposing effect, leading to increases in RSV titers. Increases in labile zinc in RSV-infected cells coincided with induction of reactive oxygen species (ROS). Both zinc depletion and addition of exogenous ROS led to enhanced RSV infection, whereas addition of the antioxidant inhibited RSV, suggesting that zinc is part of an interplay between RSV-induced oxidative stress and the host response to maintain redox balance.

Transcriptome analysis of the immune response of silkworm at the early stage of Bombyx mori bidensovirus infection

Bombyx mori bidensovirus (BmBDV) infects silkworm midgut and causes chronic flacherie disease; however, the interaction between BmBDV and silkworm is unclear. Twenty-four hours after BmBDV infection, the midgut was extracted for RNA-seq to analyze the factors associated with BmBDV-invasion and the early antiviral immune response in silkworms. The total reads from each sample were more than 16100000 and the number of expressed genes exceeded 8200. There were 334 upregulated and 272 downregulated differentially expressed genes (DEGs). Gene ontology analysis of DEGs showed that structural constituents of cuticle, antioxidant, and immune system processes were upregulated. Further analysis revealed BmBDV-mediated induction of BmorCPR23 and BmorCPR44, suggesting possible involvement in viral invasion. Antioxidant genes that protect host cells from virus-induced oxidative stress, were significantly upregulated after BmBDV infection. Several genes related to peroxisomes, apoptosis, and autophagy—which may be involved in antiviral immunity—were induced by BmBDV. These results provide insights into the mechanism of BmBDV infection and host defense.

The Effect of HCV Treatment With DAA on Iron Overload and Ferritin Levels: A Case Series

Introduction: Patients with chronic hepatitis C (CHC) are at increased risk for iron overload. Studies showed that chronic HCV patients treated with Pegylated Interferon (PEG-IFN) and who achieved sustained virologic response recovered from impaired hepcidin secretion leading to iron overload. Other studies showed that Hepatitis C virus-induced oxidative stress suppresses hepcidin expression [2,3]. HCV treatment has been transformed with the availability of direct acting anti-virals (DAAs), and SVR rates now exceed 90%. In this series, we report all patients in our practice with CHC who had an elevated serum ferritin or iron prior to treatment with DAAs and compare with levels after treatment with DAAs. To our knowledge, this is the first case series reporting outcomes in patients with high baseline iron and/or ferritin in the DAA era.2859_A Figure 1. No Caption available.Methods: We included all patients who were referred to our hepatology clinic for HCV treatment and evaluation. Data from patients who had ferritin level > 400 at the initial evaluation were collected. Results: There were 12 patients with high ferritin and/or iron/iron sat levels who met the criteria. Average age was 59 ±8 years. There were 9 (75%) males. A decrease in the levels of iron was noticed in 11/12 individuals. The average decrease in iron after treatment was 69.27 (range of 8 -149). The average decrease in ferritin was 648.25 (figure 1, table 1). 7 patients (58.3%) were alcohol users and 6 of them had quit drinking. 10 (83.33%) achieved SVR. 1 patient had compound C282Y-H63D heterozygote mutation and 2 patients had H63D homozygous mutation. Conclusion: Patients with CHC with elevated baseline iron level and/or ferritin level treated with DAAs saw a significant decrease in their iron, iron saturation and ferritin levels within a short period even in patients with hemochromatosis mutations. Whether this decrease was because of clinical factors, viral factors, genetic factors or an interplay between all three needs to be further investigated. Long term studies are needed to determine the clinical impact of decreasing iron/ferritin levels in these patients.

Antiviral activity of silymarin against Mayaro virus and protective effect in virus-induced oxidative stress

Mayaro virus (MAYV) is a neglected arbovirus belonging to the family Togaviridae. Its infection leads to Mayaro fever, with clinical manifestations such as fever, myalgia, headache, rash, arthralgia, vomiting, and diarrhea. The most prominent complaint from infected person is the long-lasting arthritis/arthralgia. The treatment for Mayaro fever is mainly symptom-based and there are no vaccines or antiviral drugs currently available, thus, natural products with anti-MAYV activity may provide a potential alternative. Recent evidences suggest that oxidative stress plays an important role in MAYV infection and compounds capable of modulating oxidative stress could represent a novel therapeutic approach in modulating MAYV-associated oxidative cellular damage. Silymarin is a complex extracted of Silybum marianum, or milk thistle, and its major active compound is silybin, which has a remarkable biological effect. Its antioxidant and antiviral effects, including its antiviral activity against the Chikungunya virus (CHIKV), prompted us to think whether silymarin could also reduce the replication of the MAYV and restore the pro-oxidant/antioxidant balance in the context of MAYV infection, leading to reduced cellular oxidative stress. We assessed the antiviral activity and protective effect of silymarin against oxidative stress in MAYV-infected HepG2 cells. Cytopathic effect inhibition, viral replication, and plaque reduction assays were used to determine the anti-MAYV activity of silymarin. Additionally, we determined whether silymarin could reduce MAYV-induced oxidative cell damage. Briefly, silymarin exhibited potent antiviral activity against MAYV and reduced MAYV-induced ROS formation and levels of malondialdehyde (MDA) and carbonyl protein, which are biomarkers of oxidative stress. In conclusion, the ability of silymarin to inhibit MAYV replication and attenuate MAYV-induce oxidative stress warrants further investigation of this compound as a novel therapeutic approach to Mayaro fever disease.