Herpes simplex virus type 1 infection induces oxidative stress and the release of bioactive lipid peroxidation by-products in mouse P19N neural cell cultures

Evaluation of potential antiviral activities of antimicrobial peptides in fish mucus

BACKGROUND

Fish skin mucus contains innate immune factors and acts as the first line of physical or chemical defense against pathogens.

OBJECTIVE

The primary aim of this study was to determine the antiviral activity of sea bream (SBr), rainbow trout (RT), and sea bass (SBa) fish skin mucus against herpes simplex virus (HSV)-1. In addition, it was aimed to associate possible antiviral activity with antimicrobial peptides (AMPs) such as cathelicidin, hepcidin, galectin 2, and C10ORF99, whose levels were determined in the mucus.

METHODS

The antiviral activity and oxidative/antioxidant status of mucus against HSV-1 virus was evaluated. In addition, AMPs, SOD, and CAT activities, and immunoglobulin M levels were also analyzed in mucus of fish.

RESULTS

Antiviral activity mucus of SBr, RT, and SBa against HSV-1 were determined as 2-4, 2-5, and 2-2, respectively. The higher antiviral activity of SBr and RT mucus compared to the mucus of SBa can be associated with higher AMP levels in them.

CONCLUSION

The skin mucus of SBr and RT may be nutritional supplement, adjuvant, and a new agent that can potentiate the effects of antimicrobial/antiviral agents.

Ginsenoside Rg5, a potent agonist of Nrf2, inhibits HSV-1 infection-induced neuroinflammation by inhibiting oxidative stress and NF-κB activation

Background

Herpes simplex virus type 1 (HSV-1), known to latently infect the host's trigeminal ganglion, can lead to severe herpes encephalitis or asymptomatic infection, potentially contributing to neurodegenerative diseases like Alzheimer's. The virus generates reactive oxygen species (ROS) that significantly impact viral replication and induce chronic inflammation through NF-κB activation. Nuclear factor E2-related factor 2 (Nrf2), an oxidative stress regulator, can prevent and treat HSV-1 infection by activating the passive defense response in the early stages of infection.

Methods and results

Our study investigated the antiviral effects of ginsenoside Rg5, an Nrf2 activator, on HSV-1 replication and several host cell signaling pathways. We found that HSV-1 infection inhibited Nrf2 activity in host cells, induced ROS/NF-κB signaling, and triggered inflammatory cytokines. However, treatment with ginsenoside Rg5 inhibited ROS/NF-κB signaling and reduced inflammatory cytokines through NRF2 induction. Interestingly, the Nrf2 inhibitor ML385 suppressed the expression of NAD(P)H quinone oxidoreductase 1(NQO1) and enhanced the expression of KEAP1 in HSV-1 infected cells. This led to the reversal of VP16 expression inhibition, a protein factor associated with HSV-1 infection, thereby promoting HSV-1 replication.

Conclusion

These findings suggest for the first time that ginsenoside Rg5 may serve as an antiviral against HSV-1 infection and could be a novel therapeutic agent for HSV-1-induced neuroinflammation.

Virus-Induced MicroRNA Modulation and Systemic Sclerosis Disease

MicroRNAs (miRNAs) are short noncoding RNA sequences that regulate gene expression at the post-transcriptional level. They are involved in the regulation of multiple pathways, related to both physiological and pathological conditions, including autoimmune diseases, such as Systemic Sclerosis (SSc). Specifically, SSc is recognized as a complex and multifactorial disease, characterized by vascular abnormalities, immune dysfunction, and progressive fibrosis, affecting skin and internal organs. Among predisposing environmental triggers, evidence supports the roles of oxidative stress, chemical agents, and viral infections, mostly related to those sustained by beta-herpesviruses such as HCMV and HHV-6. Dysregulated levels of miRNA expression have been found in SSc patients compared to healthy controls, at both the intra- and extracellular levels, providing a sort of miRNA signature of the SSc disease. Notably, HCMV/HHV-6 viral infections were shown to modulate the miRNA profile, often superposing that observed in SSc, potentially promoting pathological pathways associated with SSc development. This review summarizes the main data regarding miRNA alterations in SSc disease, highlighting their potential as prognostic or diagnostic markers for SSc disease, and the impact of the putative SSc etiological agents on miRNA modulation.

Molecular Mechanisms Associated with Neurodegeneration of Neurotropic Viral Infection

Viral infections of the central nervous system (CNS) cause variable outcomes from acute to severe neurological sequelae with increased morbidity and mortality. Viral neuroinvasion directly or indirectly induces encephalitis via dysregulation of the immune response and contributes to the alteration of neuronal function and the degeneration of neuronal cells. This review provides an overview of the cellular and molecular mechanisms of virus-induced neurodegeneration. Neurotropic viral infections influence many aspects of neuronal dysfunction, including promoting chronic inflammation, inducing cellular oxidative stress, impairing mitophagy, encountering mitochondrial dynamics, enhancing metabolic rewiring, altering neurotransmitter systems, and inducing misfolded and aggregated pathological proteins associated with neurodegenerative diseases. These pathogenetic mechanisms create a multidimensional injury of the brain that leads to specific neuronal and brain dysfunction. The understanding of the molecular mechanisms underlying the neurophathogenesis associated with neurodegeneration of viral infection may emphasize the strategies for prevention, protection, and treatment of virus infection of the CNS.

Polyphenols from Maackia amurensis Heartwood Protect Neuronal Cells from Oxidative Stress and Prevent Herpetic Infection

Here, we continued the investigation of anti-HSV-1 activity and neuroprotective potential of 14 polyphenolic compounds isolated from Maackia amurensis heartwood. We determined the absolute configurations of asymmetric centers in scirpusin A (13) and maackiazin (10) as 7R,8R and 1″S,2″S, respectively. We showed that dimeric stilbens maackin (9) and scirpusin A (13) possessed the highest anti-HSV-1 activity among polyphenols 1-14. We also studied the effect of polyphenols 9 and 13 on the early stages of HSV-1 infection. Direct interaction with the virus (virucidal activity) was the main mechanism of the antiviral activity of these compounds. The neuroprotective potential of polyphenolic compounds from M. amurensis was studied using models of 6-hydroxydopamine (6-OHDA)-and paraquat (PQ)-induced neurotoxicity. A dimeric stilbene scirpusin A (13) and a flavonoid liquiritigenin (6) were shown to be the most active compounds among the tested polyphenols. These compounds significantly increased the viability of 6-OHDA-and PQ-treated Neuro-2a cells, elevated mitochondrial membrane potential and reduced the intracellular ROS level. We also found that scirpusin A (13), liquiritigenin (6) and retusin (3) considerably increased the percentage of live Neuro-2a cells and decreased the number of early apoptotic cells. Scirpusin A (13) was the most promising compound possessing both anti-HSV-1 activity and neuroprotective potential.

Herpesviridae, Neurodegenerative Disorders and Autoimmune Diseases: What Is the Relationship between Them?

Alzheimer's disease and Parkinson's disease represent the most common forms of cognitive impairment. Multiple sclerosis is a chronic inflammatory disease of the central nervous system responsible for severe disability. An aberrant immune response is the cause of myelin destruction that covers axons in the brain, spinal cord, and optic nerves. Systemic lupus erythematosus is an autoimmune disease characterized by alteration of B cell activation, while Sjögren's syndrome is a heterogeneous autoimmune disease characterized by altered immune responses. The etiology of all these diseases is very complex, including an interrelationship between genetic factors, principally immune associated genes, and environmental factors such as infectious agents. However, neurodegenerative and autoimmune diseases share proinflammatory signatures and a perturbation of adaptive immunity that might be influenced by herpesviruses. Therefore, they might play a critical role in the disease pathogenesis. The aim of this review was to summarize the principal findings that link herpesviruses to both neurodegenerative and autoimmune diseases; moreover, briefly underlining the potential therapeutic approach of virus vaccination and antivirals.

Photodynamic augmentation of oncolytic virus therapy for central nervous system malignancies

Oncolytic viruses (OVs) have emerged as a clinical therapeutic modality potentially effective for cancers that evade conventional therapies, including central nervous system malignancies. Rationally designed combinatorial strategies can augment the efficacy of OVs by boosting tumor-selective cytotoxicity and modulating the tumor microenvironment (TME). Photodynamic therapy (PDT) of cancer not only mediates direct neoplastic cell death but also primes the TME to sensitize the tumor to secondary therapies, allowing for the combination of two potentially synergistic therapies with broader targets. Here, we created G47Δ-KR, clinical oncolytic herpes simplex virus G47Δ that expresses photosensitizer protein KillerRed (KR). Optical properties and cytotoxic effects of G47Δ-KR infection followed by amber LED illumination (peak wavelength: 585-595 nm) were examined in human glioblastoma (GBM) and malignant meningioma (MM) models in vitro. G47Δ-KR infection of tumor cells mediated KR expression that was activated by LED and produced reactive oxygen species, leading to cell death that was more robust than G47Δ-KR without light. In vivo, we tested photodynamic-oncolytic virus (PD-OV) therapy employing intratumoral injection of G47Δ-KR followed by laser light tumor irradiation (wavelength: 585 nm) in GBM and MM xenografts. PD-OV therapy was feasible in these models and resulted in potent anti-tumor effects that were superior to G47Δ-KR alone (without laser light) or laser light alone. RNA sequencing analysis of post-treatment tumor samples revealed PD-OV therapy-induced increases in TME infiltration of variable immune cell types. This study thus demonstrated the proof-of-concept that G47Δ-KR enables PD-OV therapy for neuro-oncological malignancies and warrants further research to advance potential clinical translation.

Immunopathogenesis of viral infections in neurological autoimmune disease

Autoimmune diseases develop due to self-tolerance failure in recognizing self and non-self-antigens. Several factors play a role in inducing autoimmunity, including genetic and environmental elements. Several studies demonstrated the causative role of viruses; however, some studies showed the preventive effect of viruses in the development of autoimmunity. Neurological autoimmune diseases are classified based on the targets of autoantibodies, which target intracellular or extracellular antigens rather than neurons. Several theories have been hypothesized to explain the role of viruses in the pathogenesis of neuroinflammation and autoimmune diseases. This study reviewed the current data on the immunopathogenesis of viruses in autoimmunity of the nervous system.

Neuroprotective and Antiherpetic Properties of Polyphenolic Compounds from Maackia amurensis Heartwood

In this study, we isolated a new isoflavanostilbene maackiapicevestitol (1) as a mixture of two stable conformers 1a and 1b as well as five previously known dimeric and monomeric stilbens: piceatannol (2), maackin (3), scirpusin A (4), maackiasine (5), and maackolin (6) from M. amurensis heartwood, using column chromatography on polyamide, silicagel, and C-18. The structures of these compounds were elucidated by NMR, HR-MS, and CD techniques. Maksar® obtained from M. amurensis heartwood and polyphenolics 1–6 possessed moderate anti-HSV-1 activity in cytopathic effect (CPE) inhibition and RT-PCR assays. A model of PQ-induced neurotoxicity was used to study the neuroprotective potential of polyphenolic compounds from M. amurensis. Maksar® showed the highest neuroprotective activity and increased cell viability by 18% at a concentration of 10 μg/mL. Maackolin (6) also effectively increased the viability of PQ-treated Neuro-2a cells and the value of mitochondrial membrane potential at concentrations up to 10 μΜ. Maksar® and compounds 1–6 possessed higher FRAP and DPPH-scavenging effects than quercetin. However, only compounds 1 and 4 at concentrations of 10 μM as well as Maksar® (10 μg/mL) statistically significantly reduced the level of intracellular ROS in PQ-treated Neuro-2a cells.

Manipulation of Oxidative Stress Responses by Non-Thermal Plasma to Treat Herpes Simplex Virus Type 1 Infection and Disease

Herpes simplex virus type 1 (HSV-1) is a contagious pathogen with a large global footprint, due to its ability to cause lifelong infection in patients. Current antiviral therapies are effective in limiting viral replication in the epithelial cells to alleviate clinical symptoms, but ineffective in eliminating latent viral reservoirs in neurons. Much of HSV-1 pathogenesis is dependent on its ability to manipulate oxidative stress responses to craft a cellular environment that favors HSV-1 replication. However, to maintain redox homeostasis and to promote antiviral immune responses, the infected cell can upregulate reactive oxygen and nitrogen species (RONS) while having a tight control on antioxidant concentrations to prevent cellular damage. Non-thermal plasma (NTP), which we propose as a potential therapy alternative directed against HSV-1 infection, is a means to deliver RONS that affect redox homeostasis in the infected cell. This review emphasizes how NTP can be an effective therapy for HSV-1 infections through the direct antiviral activity of RONS and via immunomodulatory changes in the infected cells that will stimulate anti-HSV-1 adaptive immune responses. Overall, NTP application can control HSV-1 replication and address the challenges of latency by decreasing the size of the viral reservoir in the nervous system.

Herpes Simplex Virus 1-Induced Ferroptosis Contributes to Viral Encephalitis

Herpes simplex virus 1 (HSV-1) is a DNA virus belonging to the family Herpesviridae. HSV-1 infection causes severe neurological disease in the central nervous system (CNS), including encephalitis. Ferroptosis is a nonapoptotic form of programmed cell death that contributes to different neurological inflammatory diseases. However, whether HSV-1 induces ferroptosis in the CNS and the role of ferroptosis in viral pathogenesis remain unclear. Here, we demonstrate that HSV-1 induces ferroptosis, as hallmarks of ferroptosis, including Fe²⁺ overload, reactive oxygen species (ROS) accumulation, glutathione (GSH) depletion, lipid peroxidation, and mitochondrion shrinkage, are observed in HSV-1-infected cultured human astrocytes, microglia cells, and murine brains. Moreover, HSV-1 infection enhances the E3 ubiquitin ligase Keap1 (Kelch-like ECH-related protein 1)-mediated ubiquitination and degradation of nuclear factor E2-related factor 2 (Nrf2), a transcription factor that regulates the expression of antioxidative genes, thereby disturbing cellular redox homeostasis and promoting ferroptosis. Furthermore, HSV-1-induced ferroptosis is tightly associated with the process of viral encephalitis in a mouse model, and the ferroptosis-activated upregulation of prostaglandin-endoperoxide synthase 2 (PTGS2) and prostaglandin E₂ (PGE₂) plays an important role in HSV-1-caused inflammation and encephalitis. Importantly, the inhibition of ferroptosis by a ferroptosis inhibitor or a proteasome inhibitor to suppress Nrf2 degradation effectively alleviated HSV-1 encephalitis. Together, our findings demonstrate the interaction between HSV-1 infection and ferroptosis and provide novel insights into the pathogenesis of HSV-1 encephalitis. IMPORTANCE Ferroptosis is a nonapoptotic form of programmed cell death that contributes to different neurological inflammatory diseases. However, whether HSV-1 induces ferroptosis in the CNS and the role of ferroptosis in viral pathogenesis remain unclear. In the current study, we demonstrate that HSV-1 infection induces ferroptosis, as Fe²⁺ overload, ROS accumulation, GSH depletion, lipid peroxidation, and mitochondrion shrinkage, all of which are hallmarks of ferroptosis, are observed in human cultured astrocytes, microglia cells, and murine brains infected with HSV-1. Moreover, HSV-1 infection enhances Keap1-dependent Nrf2 ubiquitination and degradation, which results in substantial reductions in the expression levels of antiferroptotic genes downstream of Nrf2, thereby disturbing cellular redox homeostasis and promoting ferroptosis. Furthermore, HSV-1-induced ferroptosis is tightly associated with the process of viral encephalitis in a mouse model, and the ferroptosis-activated upregulation of PTGS2 and PGE₂ plays an important role in HSV-1-caused inflammation and encephalitis. Importantly, the inhibition of ferroptosis by either a ferroptosis inhibitor or a proteasome inhibitor to suppress HSV-1-induced Nrf2 degradation effectively alleviates HSV-1-caused neuro-damage and inflammation in infected mice. Overall, our findings uncover the interaction between HSV-1 infection and ferroptosis, shed novel light on the physiological impacts of ferroptosis on the pathogenesis of HSV-1 infection and encephalitis, and provide a promising therapeutic strategy to treat this important infectious disease with a worldwide distribution.

Neutrophil Extracellular Traps and Their Possible Implications in Ocular Herpes Infection

Neutrophil extracellular traps (NETs) are net-like structures released from neutrophils. NETs predominantly contain cell-free deoxyribonucleic acid (DNA) decorated with histones and neutrophil granule proteins. Numerous extrinsic and intrinsic stimuli can induce the formation of NETs such as pathogens, cytokines, immune complexes, microcrystals, antibodies, and other physiological stimuli. The mechanism of NETosis induction can either be ROS-dependent or independent based on the catalase producing activity of the pathogen. NADPH is the source of ROS production, which in turn depends on the upregulation of Ca2+ production in the cytoplasm. ROS-independent induction of NETosis is regulated through toll-like receptors (TLRs). Besides capturing and eliminating pathogens, NETs also aggravate the inflammatory response and thus act as a double-edged sword. Currently, there are growing reports of NETosis induction during bacterial and fungal ocular infections leading to different pathologies, but there is no direct report suggesting its role during herpes simplex virus (HSV) infection. There are innumerable independent reports showing that the major effectors of NETosis are also directly affected by HSV infection, and thus, there is a strong possibility that HSV interacts with these facilitators that can either result in virally mediated modulation of NETosis or NETosis-mediated suppression of ocular HSV infection. This review focuses on the mechanism of NETs formation during different ocular pathologies, with its prime focus on highlighting their potential implications during HSV ocular infections and acting as prospective targets for the treatment of ocular diseases.

Detecting free radicals post viral infections

Free radical generation plays a key role in viral infections. While free radicals have an antimicrobial effect on bacteria or fungi, their interplay with viruses is complicated and varies greatly for different types of viruses as well as different radical species. In some cases, radical generation contributes to the defense against the viruses and thus reduces the viral load. In other cases, radical generation induces mutations or damages the host tissue and can increase the viral load. This has led to antioxidants being used to treat viral infections. Here we discuss the roles that radicals play in virus pathology. Furthermore, we critically review methods that facilitate the detection of free radicals in vivo or in vitro in viral infections.

Vaccinium bracteatum Thunb Extract Inhibits HSV-1 Infection by Regulating ER Stress and Apoptosis

Herpes simplex Type 1 (HSV-1) is a neurotropic virus that infects the peripheral and central nervous system. Usually, after primary infection in epithelial cells, HSV-1 migrates retrograde to the peripheral nervous system (PNS), where it establishes a latent infection. HSV-1 can remain latent in the nervous system, and its reactivation in the brain can rarely cause acute HSV-1 encephalitis, often a life-threatening condition, or asymptomatic reactivations that could lead to neuronal damage and ultimately neurodegenerative disorders. Acyclovir and related nucleoside analogs have been used as therapeutic agents for HSV-1 infection, but resistance to the drug can arise, and the protective effect of HSV-1 on brain cells is limited. Therefore, there is an urgent need for research into safe and effective new antiviral agents that can protect brain cells from the damage that is caused by HSV-1 infection. Vaccinium bracteatum Thunb. (VBT) is widely distributed in Korea and China, and has pharmacological actions such as anti-inflammatory, antioxidant, and antidiabetic activity. Studies on the antiviral effect of VBT on HSV-1 infection have not been reported so far. Therefore, we sought to determine the HSV-1 antiviral effect and molecular mechanism of VBT at the cellular level. We confirmed that VBT repressed the VP16 and IE genes in both Vero and SK-N-SH cells. We also found that the generation of HSV-1 virions was inhibited by VBT treatment. VBT inhibited the activities of the HSV-1-induced endoplasmic reticulum (ER) stressors PERK, ATF4, and CHOP. We confirmed that VBT inhibited the activity of apoptosis factors by regulating the expression of death receptor (DR) after HSV-1 infection. As HSV-1 is closely associated with brain diseases, the study of the antiviral drug effects and mechanism of VBT is meaningful. Further studies using animal models of infection will also be performed to determine the potential of VBT as an antiviral agent.

Serological Evidence of Herpes Simplex Virus-1 (HSV-1) Infection among Humans from Bandung, West Java Province, Indonesia

BACKGROUND: Toxoplasma gondii, Rubella virus, Cytomegalovirus, and herpes simplex virus (TORCH) infection is still a significant burden in developing countries since they potentially increase perinatal death and decrease life quality by causing congenital disorders. As part of TORCH and as one of the most common infections in humans, HSV Type 1 infection also should receive attention. HSV-1 infection induces an immediate reactive oxygen species (ROS) production, indicate that ROS plays beneficial effects in several biological functions, including innate immunity and antiviral responses. HSV-1 preferentially replicate and establish latency in different subtypes of sensory neurons and in neurons of the autonomic nervous system that are highly responsive to stress hormones, including cortisol. AIM: The objective of the study was to detect the latent HSV-1 infection in adults population and its effect on ROS and cortisol levels. PATIENTS AND METHODS: Subjects were enrolled with consecutive-sampling methods among the adults population age 18–40 years old, with no health complaints. We collected their blood to examined IgG HSV-1, ROS, and cortisol levels. RESULTS: A total of 57 subjects with 27 subjects were reactive IgG HSV-1 (herpes group) and 30 subjects were non-reactive IgG HSV-1 (non herpes groups). Mean of cortisol and ROS was 223.2904 nmol/L and 2.23337 IU/mL, respectively. There was a very weak correlation between HSV-1 infection with ROS and cortisol. CONCLUSION: There is a positive effect of latent HSV-1 infection in the adult population on cortisol ROS levels.

New Insights into the Molecular Interplay between Human Herpesviruses and Alzheimer’s Disease—A Narrative Review

Human herpesviruses (HHVs) have been implicated as possible risk factors in Alzheimer’s disease (AD) pathogenesis. Persistent lifelong HHVs infections may directly or indirectly contribute to the generation of AD hallmarks: amyloid beta (Aβ) plaques, neurofibrillary tangles composed of hyperphosphorylated tau proteins, and synaptic loss. The present review focuses on summarizing current knowledge on the molecular mechanistic links between HHVs and AD that include processes involved in Aβ accumulation, tau protein hyperphosphorylation, autophagy, oxidative stress, and neuroinflammation. A PubMed search was performed to collect all the available research data regarding the above mentioned mechanistic links between HHVs and AD pathology. The vast majority of research articles referred to the different pathways exploited by Herpes Simplex Virus 1 that could lead to AD pathology, while a few studies highlighted the emerging role of HHV 6, cytomegalovirus, and Epstein–Barr Virus. The elucidation of such potential links may guide the development of novel diagnostics and therapeutics to counter this devastating neurological disorder that until now remains incurable.

Upregulation of nuclear factor E2-related factor 2 (Nrf2) represses the replication of herpes simplex virus type 1

Background

Nuclear factor E2-related factor 2 (Nrf2) is an important transcription factor which plays a pivotal role in detoxifying reactive oxygen species (ROS) and has been more recently shown to regulate inflammatory and antiviral responses. However, the role of Nrf2 in Herpes Simplex Virus type 1 (HSV-1) infection is still unclear. In this study, the interaction between the Nrf2 and HSV-1 replication was investigated.

Methods

The levels of oxidative stress was monitored by using 8-hydroxy-2'-deoxyguanosine (8-OHdG) ELISA kits, and the dynamic changes of Nrf2-antioxidant response element (Nrf2-ARE) pathway were detected by Western Blot. The effect of Nrf2-ARE pathway on the regulation of HSV-1 proliferation was analyzed by Western Blot, Real-Time PCR and TCID₅₀ assay.

Results

HSV-1 infection induced oxidative stress. Nrf2 was activated, accompanied by the increase of its down-stream antioxidant enzyme heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO1) in the early stage of HSV-1 infection. The proliferation of HSV-1 was inhibited by overexpression of Nrf2 or treatment with its activator tert-Butylhydroquinone (tBHQ). On the contrary, silencing of Nrf2 promotes virus replication. HO-1 is involved in the regulation of IFN response, leading to efficient anti-HSV-1 effects.

Conclusion

Our observations indicate that the Nrf2-ARE pathway activates a passive defensive response in the early stage of HSV-1 infection. Targeting the Nrf2 pathway demonstrates the potential for combating HSV-1 infection.

Disrupting Neurons and Glial Cells Oneness in the Brain-The Possible Causal Role of Herpes Simplex Virus Type 1 (HSV-1) in Alzheimer's Disease

Current data strongly suggest herpes simplex virus type 1 (HSV-1) infection in the brain as a contributing factor to Alzheimer's disease (AD). The consequences of HSV-1 brain infection are multilateral, not only are neurons and glial cells damaged, but modifications also occur in their environment, preventing the transmission of signals and fulfillment of homeostatic and immune functions, which can greatly contribute to the development of disease. In this review, we discuss the pathological alterations in the central nervous system (CNS) cells that occur, following HSV-1 infection. We describe the changes in neurons, astrocytes, microglia, and oligodendrocytes related to the production of inflammatory factors, transition of glial cells into a reactive state, oxidative damage, Aβ secretion, tau hyperphosphorylation, apoptosis, and autophagy. Further, HSV-1 infection can affect processes observed during brain aging, and advanced age favors HSV-1 reactivation as well as the entry of the virus into the brain. The host activates pattern recognition receptors (PRRs) for an effective antiviral response during HSV-1 brain infection, which primarily engages type I interferons (IFNs). Future studies regarding the influence of innate immune deficits on AD development, as well as supporting the neuroprotective properties of glial cells, would reveal valuable information on how to harness cytotoxic inflammatory milieu to counter AD initiation and progression.

Potential Role for Herpesviruses in Alzheimer's Disease

Across the fields of virology and neuroscience, the role of neurotropic viruses in Alzheimer's disease (AD) has received renewed enthusiasm, with a particular focus on human herpesviruses (HHVs). Recent genomic analyses of brain tissue collections and investigations of the antimicrobial responses of amyloid-β do not exclude a role of HHVs in contributing to or accelerating AD pathogenesis. Due to continued expansion in our aging cohort and the lack of effective treatments for AD, this composition examines a potential neuroviral theory of AD in light of these recent data. Consideration reveals a possible viral "Hit-and-Run" scenario of AD, as well as neurobiological mechanisms (i.e., neuroinflammation, protein quality control, oxidative stress) that may increase risk for AD following neurotropic infection. Although limitations exist, this theoretical framework reveals several novel therapeutic targets that may prove efficacious in AD.

IFN-λ Regulates Neutrophil Biology to Suppress Inflammation in Herpes Simplex Virus-1-Induced Corneal Immunopathology

HSV-1 infection of the cornea causes a severe immunoinflammatory and vision-impairing condition called herpetic stromal keratitis (SK). The virus replication in corneal epithelium followed by neutrophil- and CD4⁺ T cell-mediated inflammation plays a dominant role in SK. Although previous studies demonstrate critical functions of type I IFNs (IFN-α/β) in HSV-1 infection, the role of recently discovered IFN-λ (type III IFN), specifically at the corneal mucosa, is poorly defined. Our study using a mouse model of SK pathogenesis shows that HSV-1 infection induces a robust IFN-λ response compared with type I IFN production at the corneal mucosal surface. However, the normal progression of SK indicates that the endogenous IFN responses are insufficient to suppress HSV-1-induced corneal pathology. Therefore, we examined the therapeutic efficacy of exogenous rIFN-λ during SK progression. Our results show that rIFN-λ therapy suppressed inflammatory cell infiltration in the cornea and significantly reduced the SK pathologic condition. Early rIFN-λ treatment significantly reduced neutrophil and macrophage infiltration, and IL-6, IL-1β, and CXCL-1 production in the cornea. Notably, the virucidal capacity of neutrophils and macrophages measured by reactive oxygen species generation was not affected. Similarly, ex vivo rIFN-λ treatment of HSV-1-stimulated bone marrow-derived neutrophils significantly promoted IFN-stimulated genes without affecting reactive oxygen species production. Collectively, our data demonstrate that exogenous topical rIFN-λ treatment during the development and progression of SK could represent a novel therapeutic approach to control HSV-1-induced inflammation and associated vision impairment.

Reactive oxygen species as potential antiviral targets

Reactive oxygen species (ROS) are by-products of cellular metabolism and can be either beneficial, at low levels, or deleterious, at high levels, to the cell. It is known that several viral infections can increase oxidative stress, which is mainly facilitated by viral-induced imbalances in the antioxidant defence mechanisms of the cell. While the exact role of ROS in certain viral infections (adenovirus and dengue virus) remains unknown, other viruses can use ROS for enhancement of pathogenesis (SARS coronavirus and rabies virus) or replication (rhinovirus, West Nile virus and vesicular stomatitis virus) or both (hepatitis C virus, human immunodeficiency virus and influenza virus). While several viral proteins (mainly for hepatitis C and human immunodeficiency virus) have been identified to play a role in ROS formation, most mediators of viral ROS modulation are yet to be elucidated. Treatment of viral infections, including hepatitis C virus, human immunodeficiency virus and influenza virus, with ROS inhibitors has shown a decrease in both pathogenesis and viral replication both in vitro and in animal models. Clinical studies indicating the potential for targeting ROS-producing pathways as possible broad-spectrum antiviral targets should be evaluated in randomized controlled trials.

In Vitro Analysis of the Antioxidant and Antiviral Activity of Embelin against Herpes Simplex Virus-1

Herpes simplex virus-1 (HSV-1) causes a wide range of infections from mild to life-threatening in the human population. There are effective treatments for HSV-1 infections that are limited due HSV-1 latency and development of resistance to current therapeutics. The goal of this study was to investigate the antioxidant and antiviral effects of embelin on HSV-1 in cultured Vero cells. Oxidative stress was verified by an extensive production of a reactive oxygen species (ROS) H2O2. Vero cells were infected with a recombinant strain of HSV-1 and antiviral assays, time course attachment, penetration, and post penetration assays, confocal microscopy, qPCR, and antioxidant assays were conducted. Our results lead to the conclusion that embelin is noncytotoxic at concentrations tested ranging from 20 to 70 µM. Treatment of HSV-1 virions with embelin resulted in 98.7-100% inhibition and affected the early stage of HSV-1 infection of Vero cells, by inhibiting the attachment and penetration of HSV-1 virions to host cells. Treatment of virions with concentrations of embelin ranging from 35 to 60 µM significantly reduced the production of H2O2. In conclusion, embelin reduces oxidative damage caused by HSV-1 infection and is an effective antiviral to reduce the infection of HSV-1 in cultured Vero cells. Further studies are needed to explore the possibility of embelin as a medicinal agent.

Antiviral Effects of Polyphenols from Marine Algae

The disease-preventive and medicinal properties of plant polyphenolic compounds have long been known. As active ingredients, they are used to prevent and treat many noncommunicable diseases. In recent decades, marine macroalgae have attracted the attention of biotechnologists and pharmacologists as a promising and almost inexhaustible source of polyphenols. This heterogeneous group of compounds contains many biopolymers with unique structure and biological properties that exhibit high anti-infective activity. In the present review, the authors focus on the antiviral potential of polyphenolic compounds (phlorotannins) from marine algae and consider the mechanisms of their action as well as other biological properties of these compounds that have effects on the progress and outcome of viral infections. Effective nutraceuticals, to be potentially developed on the basis of algal polyphenols, can also be used in the complex therapy of viral diseases. It is necessary to extend in vivo studies on laboratory animals, which subsequently will allow proceeding to clinical tests. Polyphenolic compounds have a great potential as active ingredients to be used for the creation of new antiviral pharmaceutical substances.

Multiple Herpes Simplex Virus-1 (HSV-1) Reactivations Induce Protein Oxidative Damage in Mouse Brain: Novel Mechanisms for Alzheimer's Disease Progression

Compelling evidence supports the role of oxidative stress in Alzheimer's disease (AD) pathophysiology. Interestingly, Herpes simplex virus-1 (HSV-1), a neurotropic virus that establishes a lifelong latent infection in the trigeminal ganglion followed by periodic reactivations, has been reportedly linked both to AD and to oxidative stress conditions. Herein, we analyzed, through biochemical and redox proteomic approaches, the mouse model of recurrent HSV-1 infection we previously set up, to investigate whether multiple virus reactivations induced oxidative stress in the mouse brain and affected protein function and related intracellular pathways. Following multiple HSV-1 reactivations, we found in mouse brains increased levels of oxidative stress hallmarks, including 4-hydroxynonenal (HNE), and 13 HNE-modified proteins whose levels were found significantly altered in the cortex of HSV-1-infected mice compared to controls. We focused on two proteins previously linked to AD pathogenesis, i.e., glucose-regulated protein 78 (GRP78) and collapsin response-mediated protein 2 (CRMP2), which are involved in the unfolded protein response (UPR) and in microtubule stabilization, respectively. We found that recurrent HSV-1 infection disables GRP78 function and activates the UPR, whereas it prevents CRMP2 function in mouse brains. Overall, these data suggest that repeated HSV-1 reactivation into the brain may contribute to neurodegeneration also through oxidative damage.

Marine Algal Antioxidants as Potential Vectors for Controlling Viral Diseases

As the COVID-19 epidemic expands in the world, and with the previous SARS epidemic, avian flu, Ebola and AIDS serving as a warning, biomedical and biotechnological research has the task to find solutions to counteract viral entry and pathogenesis. A novel approach can come from marine chemodiversity, recognized as a relevant source for developing a future natural "antiviral pharmacy". Activities of antioxidants against viruses can be exploited to cope with human viral infection, from single individual infections to protection of populations. There is a potentially rich and fruitful reservoir of such compounds thanks to the plethora of bioactive molecules and families present in marine microorganisms. The aim of this communication is to present the state-of-play of what is known on the antiviral activities recognized in (micro)algae, highlighting the different molecules from various algae and their mechanisms of actions, when known. Given the ability of various algal molecules-mainly sulfated polysaccharides-to inhibit viral infection at Stage I (adsorption and invasion of cells), we envisage a need to further investigate the antiviral ability of algae, and their mechanisms of action. Given the advantages of microalgal production compared to other organisms, the opportunity might become reality in a short period of time.

Viral mimetic priming enhances α-synuclein-induced degeneration: Implications for Parkinson's disease

Evidence is accumulating to suggest that viral infections and consequent viral-mediated neuroinflammation may contribute to the etiology of idiopathic Parkinson's disease. Moreover, viruses have been shown to influence α-synuclein oligomerization as well as the autophagic clearance of abnormal intra-cellular proteins aggregations, both of which are key neuropathological events in Parkinson's disease pathogenesis. To further investigate the interaction between viral-mediated neuroinflammation and α-synuclein aggregation in the context of Parkinson's disease, this study sought to determine the impact of viral neuroinflammatory priming on α-synuclein aggregate-induced neuroinflammation and neurotoxicity in the rat nigrostriatal pathway. To do so, male Sprague-Dawley rats were intra-nigrally injected with a synthetic mimetic of viral dsRNA (poly I:C) followed two weeks later by a peptidomimetic small molecule which accelerates α-synuclein fibril formation (FN075). The impact of the viral priming on α-synuclein aggregation-induced neuroinflammation, neurodegeneration and motor dysfunction was assessed. We found that prior administration of the viral mimetic poly I:C significantly exacerbated or precipitated the α-synuclein aggregate induced neuropathological and behavioral effects. Specifically, sequential exposure to the two challenges caused a significant increase in nigral microgliosis (p < 0.001) and astrocytosis (p < 0.01); precipitated a significant degeneration of the nigrostriatal cell bodies (p < 0.05); and precipitated a significant impairment in forelimb kinesis (p < 0.01) and sensorimotor integration (p < 0.01). The enhanced sensitivity of the nigrostriatal neurons to pathological α-synuclein aggregation after viral neuroinflammatory priming further suggests that viral infections may contribute to the etiology and pathogenesis of Parkinson's disease.

NF-κB-Dependent Production of ROS and Restriction of HSV-1 Infection in U937 Monocytic Cells

Herpes simplex virus 1 (HSV-1) can infect a wide range of cell types, including cells of the adaptive and innate immunity but, normally, it completes a fully-permissive replication cycle only in epithelial or neural cells. Complex mechanisms controlling this delicate balance in immune cells and consequent restriction of HSV-1 infection in these cells have not been completely elucidated. We have recently demonstrated that the transcription factor nuclear factor kappa B (NF-κB) can act as a main permissiveness regulator of HSV-1 infection in monocytic cells, however, mediators involved in this regulation have not been identified. To better define mechanisms involved in this phenomenon and, particularly, the possible involvement of ROS, wild type U937 cells or U937 cells stably transfected with a dominant-negative (DN) IκB-mutant and selenium-containing compounds, as anti-oxidants, were utilized. The main results can be summarized as follows. HSV-1 infection induces an immediate ROS production in U937 monocytic cells that can efficiently activate NF-κB but not in DN-IκB-mutant cells. Treatment with selenium-containing antioxidants efficiently inhibited HSV-1-induced ROS generation while producing increased levels of HSV-1 replication and a reduction of HSV-1-induced NF-κB activation in U937 monocytic cells. Our results suggest a scenario in which an efficient NF-κB-dependent ROS production in response to infection could contribute in limiting HSV-1 replication in monocytes/macrophages, thus avoiding possible irreparable damage to the innate immune system of the host during HSV-1 infection.

Herpes Simplex Virus Type 1 Infection of the Central Nervous System: Insights Into Proposed Interrelationships With Neurodegenerative Disorders

Herpes simplex virus type 1 (HSV-1) is highly prevalent in humans and can reach the brain without evident clinical symptoms. Once in the central nervous system (CNS), the virus can either reside in a quiescent latent state in this tissue, or eventually actively lead to severe acute necrotizing encephalitis, which is characterized by exacerbated neuroinflammation and prolonged neuroimmune activation producing a life-threatening disease. Although HSV-1 encephalitis can be treated with antivirals that limit virus replication, neurological sequelae are common and the virus will nevertheless remain for life in the neural tissue. Importantly, there is accumulating evidence that suggests that HSV-1 infection of the brain both, in symptomatic and asymptomatic individuals could lead to neuronal damage and eventually, neurodegenerative disorders. Here, we review and discuss acute and chronic infection of particular brain regions by HSV-1 and how this may affect neuron and cognitive functions in the host. We review potential cellular and molecular mechanisms leading to neurodegeneration, such as protein aggregation, dysregulation of autophagy, oxidative cell damage and apoptosis, among others. Furthermore, we discuss the impact of HSV-1 infection on brain inflammation and its potential relationship with neurodegenerative diseases.

Duck Plague Virus Promotes DEF Cell Apoptosis by Activating Caspases, Increasing Intracellular ROS Levels and Inducing Cell Cycle S-Phase Arrest

Background: Duck plague virus (DPV) can induce apoptosis in duck embryo fibroblasts (DEFs) and in infected ducks, but the molecular mechanism of DPV-induced apoptosis remains unknown. Methods: We first used qRT-PCR and a Caspase-Glo assay to determine whether the caspase protein family plays an important role in DPV-induced apoptosis. Then, we used an intracellular ROS detection kit and the mitochondrial probe JC-1 to respectively detect ROS levels and mitochondrial membrane potential (MMP). Finally, flow cytometry was used to detect apoptosis and cell cycle progression. Results: In this study, the mRNA levels and enzymatic activities of caspase-3, caspase-7, caspase-8, and caspase-9 were significantly increased during DPV-induced apoptosis. The caspase inhibitors Z-DEVD-FMK, Z-LEHD-FMK, and Q-VD-Oph could inhibit DPV-induced apoptosis and promote viral replication. Subsequently, a significant decrease in MMP and an increase in the intracellular ROS levels were observed. Further study showed that pretreating infected cells with NAC (a ROS scavenger) decreased the intracellular ROS levels, increased the MMP, inhibited apoptosis, and promoted viral replication. Finally, we showed that DPV infection can cause cell cycle S-phase arrest. Conclusions: This study shows that DPV causes cell cycle S-phase arrest and leads to apoptosis through caspase activation and increased intracellular ROS levels. These findings may be useful for gaining an understanding of the pathogenesis of DPV and the apoptotic pathways induced by α-herpesviruses.

Antiviral and Antioxidant Properties of Echinochrome A

The aim of this study was to examine the in vitro antioxidant and antiviral activities of echinochrome A and echinochrome-based antioxidant composition against tick-borne encephalitis virus (TBEV) and herpes simplex virus type 1 (HSV-1). The antioxidant composition, which is a mixture of echinochrome A, ascorbic acid, and α-tocopherol (5:5:1), showed higher antioxidant and antiviral effects than echinochrome A. We suppose that echinochrome A and its composition can both directly affect virus particles and indirectly enhance antioxidant defense mechanisms in the hosting cell. The obtained results allow considering the echinochrome A and the composition of antioxidants on its basis as the promising agents with the both antioxidant and antiviral activities.

Proteomics of Bronchoalveolar Lavage Fluid Reveals a Lung Oxidative Stress Response in Murine Herpesvirus-68 Infection

Murine herpesvirus-68 (MHV-68) productively infects mouse lungs, exhibiting a complex pathology characteristic of both acute viral infections and chronic respiratory diseases. We sought to discover proteins differentially expressed in bronchoalveolar lavage (BAL) from mice infected with MHV-68. Mice were infected intranasally with MHV-68. After nine days, as the lytic phase of infection resolved, differential BAL proteins were identified by two-dimensional (2D) electrophoresis and mass spectrometry. Of 23 unique proteins, acute phase proteins, vitamin A transport, and oxidative stress response factors Pdx6 and EC-SOD (Sod3) were enriched. Correspondingly, iNOS2 was induced in lung tissue by seven days post-infection. Oxidative stress was partly a direct result of MHV-68 infection, as reactive oxygen species (ROS) were induced in cultured murine NIH3T3 fibroblasts and human lung A549 cells infected with MHV-68. Finally, mice infected with a recombinant MHV-68 co-expressing inflammatory cytokine murine interleukin 6 (IL6) showed exacerbated oxidative stress and soluble type I collagen characteristic of tissue recovery. Thus, oxidative stress appears to be a salient feature of MHV-68 pathogenesis, in part caused by lytic replication of the virus and IL6. Proteins and small molecules in lung oxidative stress networks therefore may provide new therapeutic targets to ameliorate respiratory virus infections.

Herpes Simplex Virus 1 Infection Promotes the Growth of a Subpopulation of Tumor Cells in Three-Dimensional Uveal Melanoma Cultures

Cancer cells are exposed to HSV-1 during oncolytic virotherapy with the intention of killing tumor cells. Our observations reported here suggest that potential dangers of HSV-1 oncolytic therapy include promotion of growth of some tumor cells. Furthermore, our findings raise the possibility that HSV-1 infection of neoplastic cells during natural infections or vaccinations may promote the growth of tumors. Our study indicates that HSV-1 infection of 3D tumor cell cultures provides an experimental platform in which mechanisms of HSV-1-mediated promotion of tumor cell growth can be effectively studied.

Herpes simplex virus 1 (HSV-1)-mediated oncolytic therapy is an emerging cancer treatment modality with potential effectiveness against a variety of malignancies. To better understand the interaction of HSV-1 with neoplastic cells, we inoculated three-dimensional (3D) cultures of human uveal melanoma cells with HSV-1. 3D melanoma cultures were established by placing tumor cells on the surface of a Matrigel matrix, which was followed by the growth of tumor cells on the matrix surface and invasion of the Matrigel matrix by some tumor cells to form multicellular tumor spheroids within the matrix. When established 3D melanoma cultures were inoculated with HSV-1 by placing virus on the surface of cultures, virus infection caused extensive death of melanoma cells growing on the surface of the 3D matrix and significantly decreased the number of tumor cell spheroids within the matrix. However, HSV-1 infection did not lead to a complete destruction of tumor cells in the 3D cultures during a 17-day observation period and, surprisingly, HSV-1 infection promoted the growth of some melanoma cells within the matrix as determined by the significantly increased size of residual viable multicellular tumor spheroids in virus-inoculated 3D cultures at 17 days after virus inoculation. Acyclovir treatment inhibited HSV-1-induced tumor cell killing but did not block the virus infection-induced increase in spheroid size. These findings suggest that although HSV-1 oncolytic virotherapy may cause extensive tumor cell killing, it may also be associated with the unintended promotion of the growth of some tumor cells.

IMPORTANCE Cancer cells are exposed to HSV-1 during oncolytic virotherapy with the intention of killing tumor cells. Our observations reported here suggest that potential dangers of HSV-1 oncolytic therapy include promotion of growth of some tumor cells. Furthermore, our findings raise the possibility that HSV-1 infection of neoplastic cells during natural infections or vaccinations may promote the growth of tumors. Our study indicates that HSV-1 infection of 3D tumor cell cultures provides an experimental platform in which mechanisms of HSV-1-mediated promotion of tumor cell growth can be effectively studied.

Physiological costs of infection: herpesvirus replication is linked to blood oxidative stress in equids

Viruses may have a dramatic impact on the health of their animal hosts. The patho-physiological mechanisms underlying viral infections in animals are, however, not well understood. It is increasingly recognized that oxidative stress may be a major physiological cost of viral infections. Here we compare three blood-based markers of oxidative status in herpes positive and negative individuals of the domestic horse (Equus ferus caballus) and of both captive and free-ranging Mongolian khulan (Equus hemionus hemionus) and plains zebra (Equus quagga). Herpes positive free-ranging animals had significantly more protein oxidative damage and lower glutathione peroxidase (antioxidant enzyme) than negative ones, providing correlative support for a link between oxidative stress and herpesvirus infection in free-living equids. Conversely, we found weak evidence for oxidative stress in herpes positive captive animals. Hence our work indicates that environment (captive versus free living) might affect the physiological response of equids to herpesvirus infection. The Mongolian khulan and the plains zebra are currently classified as near threatened by the International Union for Conservation of Nature. Thus, understanding health impacts of pathogens on these species is critical to maintaining viable captive and wild populations.

Impaired oxidative status as a potential predictor in clinical manifestations of herpes zoster

Oxidative stress, caused by an imbalance between reactive oxygen species and antioxidants, is related to many dermatologic diseases. Increased reactive oxygen species is also associated with various decreased T-cell immune responses. The incidence and severity of herpes zoster (HZ), which is caused by the reactivation of varicella-zoster virus, increase with age because of declining cell-mediated immunity. The main purpose of this study was to assess the levels of oxidative stress biomarkers in patients with HZ compared with control subjects. In this case-control study, the serum levels of total antioxidant capacity (TAC), total oxidant status (TOS), oxidative stress index, glutathione, superoxide dismutase, and total polyphenol content (TPC) in 43 patients with HZ and 47 age-matched controls were determined, and their biomarker patterns were compared. TAC and TPC levels were significantly lower in patients with HZ; however, TOS and oxidative stress index levels were significantly higher in comparison with the control (P < .001). In addition, a significantly strong negative correlation was found between TAC and TPC with TOS levels in patients with HZ (r = -.79, P < .001; r = -.81, P < .001, respectively). Our findings showed an oxidative stress imbalance in HZ. Whether this change correlates with HZ pathogenesis or is a consequence of the inflammatory response to HZ needs more investigation.

A role for viral infections in Parkinson's etiology?

Despite over 200 years since its first description by James Parkinson, the cause(s) of most cases of Parkinson's disease (PD) are yet to be elucidated. The disparity between the current understanding of PD symptomology and pathology has led to numerous symptomatic therapies, but no strategy for prevention or disease cure. An association between certain viral infections and neurodegenerative diseases has been recognized, but largely ignored or dismissed as controversial, for decades. Recent epidemiological studies have renewed scientific interest in investigating microbial interactions with the central nervous system (CNS). This review examines past and current clinical findings and overviews the potential molecular implications of viruses in PD pathology.

Ochratoxin A-induced autophagy in vitro and in vivo promotes porcine circovirus type 2 replication

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium. Porcine circovirus type 2 (PCV2) is recognized as the causative agent of porcine circovirus-associated diseases. Recently, we reported that low doses of OTA promoted PCV2 replication in vitro and in vivo, but the underlying mechanism needed further investigation. The present studies further confirmed OTA-induced PCV2 replication promotion as measured by cap protein expression, viral titer, viral DNA copies and the number of infected cells. Our studies also showed that OTA induced autophagy in PK-15 cells, as assessed by the markedly increased expression of microtubule-associated protein 1 light chain 3 (LC3)-II, autophagy-related protein 5 (ATG5), and Beclin-1 and the accumulation of green fluorescent protein (GFP)-LC3 dots. OTA induced complete autophagic flux, which was detected by monitoring p62 degradation and LC3-II turnover using immunoblotting. Inhibition of autophagy by 3-methylademine (3-MA) and chloroquine (CQ) significantly attenuated OTA-induced PCV2 replication promotion. The observed phenomenon was further confirmed by the knock-down of ATG5 or Beclin-1 by specific siRNA. Further studies showed that N-acetyl-L-cysteine (NAC), an ROS scavenger could block autophagy induced by OTA, indicating that ROS may be involved in the regulation of OTA-induced autophagy. Furthermore, we observed significant increases in OTA concentrations in lung, spleen, kidney, liver and inguinal lymph nodes (ILN) and bronchial lymph nodes (BLN) of pigs fed 75 and 150 μg/kg OTA compared with controls in vivo. Administration of 75 μg/kg OTA significantly increased PCV2 replication and autophagy in the lung, spleen, kidney and BLN of pigs. Taken together, it could be concluded that OTA-induced autophagy in vitro and in vivo promotes PCV2 replication.

Oxidative stress biomarkers are associated with visible clinical signs of a disease in frigatebird nestlings

Infectious diseases are one of the most common threats for both domestic and wild animals, but little is known about the effects on the physiological condition and survival of wild animals. Here, we have tested for the first time in a wild vertebrate facing a viral disease possibly due to herpesvirus (i) whether nestlings with either low levels of oxidative damage or high levels of antioxidant protection are less susceptible to develop visible clinical signs, (ii) whether the disease is associated with the nestlings’ oxidative status, (iii) whether the association between the disease and oxidative status is similar between males and females (iv), and whether cloacal and tracheal swabs might be used to detect herpesvirus. To address our questions, we took advantage of a population of Magnificent frigatebirds (Fregata magnificens) whose nestlings have experienced high mortality rates in recent times. Our work shows that (i) blood lipid oxidative damage is associated with observable clinical signs and survival probabilities of nestling frigatebirds, and (ii) that high glutathione levels in red blood cells are associated with the emergence of visible clinical signs of the disease. Our work provides evidence that differences in the oxidative status of nestlings might underlie individual health and survival.

Diphenyl Diselenide Reduces Oxidative Stress and Toxicity Caused by HSV-2 Infection in Mice

Herpes simplex viruses can cause uncommon systemic complications as acute liver failure (ALT) or urinary tract dysfunctions. Diphenyl diselenide, (PhSe)₂ , a classical studied organic selenium compound, has a novel antiviral action against HSV-2 infection and well-known antioxidant and anti-inflammatory properties. This study aimed to investigate if (PhSe)₂ reduces oxidative stress and systemic toxicity caused by HSV-2 infection in mice. Adult BALB/c mice were pre-treated with (PhSe)₂ (5 mg kg^-1 /day, intragastric, i.g.) during 5 days; at day 6 mice were infected with HSV-2 (10 μl-10⁵ PFU/mL^-1 ) and post-treated with (PhSe)₂ for more 5 days. At day 11, they were killed and samples of liver and kidney were obtained to determine: reactive species (RS); malondialdehyde (MDA), and non-protein thiols (NPSH) levels; the activities of antioxidant enzymes, superoxide dismutase (SOD), and catalase (CAT). The activities of adenosine deaminase (ADA), Na⁺ /K⁺ -ATPase (liver and kidney); alanine aminotransferase (ALT), aspartate aminotransferase (AST), and the levels of urea (plasma) were determined as markers of hepatic and renal toxicity. The results revealed that (PhSe)₂ treatment was effective against the increase of renal and hepatic oxidative stress in infected mice and also normalized hepatic and renal ADA activity. It recovered the activity of Na⁺ /K⁺ - and was not effective against the increase in urea levels in infected mice. Different from (PhSe)₂ , acyclovir (positive control), caused an increase in ADA activity and a decrease in hepatic CAT activity. Considering the interest of alternative therapies to treat HSV-2 infections and secondary complications, (PhSe)₂ become a notable candidate. J. Cell. Biochem. 118: 1028-1037, 2017. © 2016 Wiley Periodicals, Inc.

Pivotal Role of Receptor-Interacting Protein Kinase 1 and Mixed Lineage Kinase Domain-Like in Neuronal Cell Death Induced by the Human Neuroinvasive Coronavirus OC43

Human coronaviruses (HCoV) are respiratory pathogens with neuroinvasive, neurotropic, and neurovirulent properties, highlighting the importance of studying the potential implication of these viruses in neurological diseases. The OC43 strain (HCoV-OC43) was reported to induce neuronal cell death, which may participate in neuropathogenesis. Here, we show that HCoV-OC43 harboring two point mutations in the spike glycoprotein (rOC/U_s183-241) was more neurovirulent than the wild-type HCoV-OC43 (rOC/ATCC) in mice and induced more cell death in murine and human neuronal cells. To evaluate the role of regulated cell death (RCD) in HCoV-OC43-mediated neural pathogenesis, we determined if knockdown of Bax, a key regulator of apoptosis, or RIP1, a key regulator of necroptosis, altered the percentage of neuronal cell death following HCoV-OC43 infection. We found that Bax-dependent apoptosis did not play a significant role in RCD following infection, as inhibition of Bax expression mediated by RNA interference did not confer cellular protection against the cell death process. On the other hand, we demonstrated that RIP1 and MLKL were involved in neuronal cell death, as RIP1 knockdown and chemical inhibition of MLKL significantly increased cell survival after infection. Taken together, these results indicate that RIP1 and MLKL contribute to necroptotic cell death after HCoV-OC43 infection to limit viral replication. However, this RCD could lead to neuronal loss in the mouse CNS and accentuate the neuroinflammation process, reflecting the severity of neuropathogenesis.

IMPORTANCE

Because they are naturally neuroinvasive and neurotropic, human coronaviruses are suspected to participate in the development of neurological diseases. Given that the strain OC43 is neurovirulent in mice and induces neuronal cell death, we explored the neuronal response to infection by characterizing the activation of RCD. Our results revealed that classical apoptosis associated with the Bax protein does not play a significant role in HCoV-OC43-induced neuronal cell death and that RIP1 and MLKL, two cellular proteins usually associated with necroptosis (an RCD back-up system when apoptosis is not adequately induced), both play a pivotal role in the process. As necroptosis disrupts cellular membranes and allows the release of damage-associated molecular patterns (DAMP) and possibly induces the production of proinflammatory cytokines, it may represent a proinflammatory cell death mechanism that contributes to excessive neuroinflammation and neurodegeneration and eventually to neurological disorders after a coronavirus infection.

Herpes Simplex Virus-Type1 (HSV-1) Impairs DNA Repair in Cortical Neurons

Several findings suggest that Herpes simplex virus-1 (HSV-1) infection plays a role in the neurodegenerative processes that characterize Alzheimer’s disease (AD), but the underlying mechanisms have yet to be fully elucidated. Here we show that HSV-1 productive infection in cortical neurons causes the accumulation of DNA lesions that include both single (SSBs) and double strand breaks (DSBs), which are reported to be implicated in the neuronal loss observed in neurodegenerative diseases. We demonstrate that HSV-1 downregulates the expression level of Ku80, one of the main components of non-homologous end joining (NHEJ), a major pathway for the repair of DSBs. We also provide data suggesting that HSV-1 drives Ku80 for proteasomal degradation and impairs NHEJ activity, leading to DSB accumulation. Since HSV-1 usually causes life-long recurrent infections, it is possible to speculate that cumulating damages, including those occurring on DNA, may contribute to virus induced neurotoxicity and neurodegeneration, further suggesting HSV-1 as a risk factor for neurodegenerative conditions.

Multifaceted Histone H3 Methylation and Phosphorylation Readout by the Plant Homeodomain Finger of Human Nuclear Antigen Sp100C

The decoding of histone post-translational modifications by chromatin-binding modules ("readers") constitutes one major mechanism of epigenetic regulation. Nuclear antigen Sp100 (SPECKLED, 100 kDa), a constitutive component of the promyelocytic leukemia nuclear bodies, plays key roles in intrinsic immunity and transcriptional repression. Sp100C, a splicing isoform specifically up-regulated upon interferon stimulation, harbors a unique tandem plant homeodomain (PHD) finger and bromodomain at its C terminus. Combining structural, quantitative binding, and cellular co-localization studies, we characterized Sp100C PHD finger as an unmethylated histone H3 Lys(4) (H3K4me0) reader that tolerates histone H3 Thr(3) phosphorylation (H3T3ph), histone H3 Lys(9) trimethylation (H3K9me3), and histone H3 Ser(10) phosphorylation (H3S10ph), hallmarks associated with the mitotic chromosome. In contrast, whereas H3K4me0 reader activity is conserved in Sp140, an Sp100C paralog, the multivalent tolerance of H3T3ph, H3K9me3, and H3S10ph was lost for Sp140. The complex structure determined at 2.1 Å revealed a highly coordinated lysine ϵ-amine recognition sphere formed by an extended N-terminal motif for H3K4me0 readout. Interestingly, reader pocket rigidification by disulfide bond formation enhanced H3K4me0 binding by Sp100C. An additional complex structure solved at 2.7 Å revealed that H3T3ph is recognized by the arginine residue, Arg(713), that is unique to the PHD finger of Sp100C. Consistent with a restrictive cellular role of Sp100C, these results establish a direct chromatin targeting function of Sp100C that may regulate transcriptional gene silencing and promyelocytic leukemia nuclear body-mediated intrinsic immunity in response to interferon stimulation.

Redox Imbalance and Viral Infections in Neurodegenerative Diseases

Reactive oxygen species (ROS) are essential molecules for many physiological functions and act as second messengers in a large variety of tissues. An imbalance in the production and elimination of ROS is associated with human diseases including neurodegenerative disorders. In the last years the notion that neurodegenerative diseases are accompanied by chronic viral infections, which may result in an increase of neurodegenerative diseases progression, emerged. It is known in literature that enhanced viral infection risk, observed during neurodegeneration, is partly due to the increase of ROS accumulation in brain cells. However, the molecular mechanisms of viral infection, occurring during the progression of neurodegeneration, remain unclear. In this review, we discuss the recent knowledge regarding the role of influenza, herpes simplex virus type-1, and retroviruses infection in ROS/RNS-mediated Parkinson's disease (PD), Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS).

BHV-1 induced oxidative stress contributes to mitochondrial dysfunction in MDBK cells

The levels of cellular reactive oxygen species (ROS) and ATP as well as the mitochondrial membrane potential (MMP) in response to bovine herpesvirus 1 (BHV-1) infection of MDBK cells were measured, respectively. BHV-1 infection increased ROS production which depended on viral entry, and de novo protein expression and/or DNA replication. Vice versa, excessive ROS was required for efficient viral replication. Levels of both ATP and MMP were significantly decreased after BHV-1 infection. Interestingly, the loss of MMP was ameliorated by ROS depression. Collectively, ROS dependent mitochondrial damage and ultimately disruption of energy metabolism (ATP depletion) are a potential pathogenic mechanism for BHV-1 infection.

Oxidative stress favours herpes virus infection in vertebrates: a meta-analysis

Herpes viruses are responsible for a variety of pathological effects in humans and in both wild and domestic animals. One mechanism that has been proposed to facilitate replication and activity of herpes viruses is oxidative stress (OS). We used meta-analytical techniques to test the hypotheses that (1) herpes virus infection causes OS and (2) supplementation of antioxidants reduces virus load, indicating that replication is favoured by a state of OS. Results based on studies on mammals, including humans, and birds show that (1) OS is indeed increased by herpes virus infection across multiple tissues and species, (2) biomarkers of OS may change differently between tissues, and (3) the effect size does not differ among different virus strains. In addition, the increase of oxidative damage in blood (tissue commonly available in ecological studies) was similar to that in the tissues most sensitive to the herpes virus. Our results also show that administration of antioxidants reduces virus yield, indicating that a condition of OS is favorable for the viral replication. In addition, some antioxidants may be more efficient than others in reducing herpes virus yield. Our results point to a potential mechanism linking herpes virus infection to individual health status.

Antiviral Action of Diphenyl Diselenide on Herpes Simplex Virus 2 Infection in Female BALB/c Mice

Diphenyl diselenide, (PhSe)2 , is an organoselenium compound with pharmacological actions mostly related to antioxidant and anti-inflammatory properties. The study investigated its antiviral and virucidal actions against herpes simplex virus 2 (HSV-2) infection in vitro and in a vaginal infection model in mice. The plaque reduction assay indicated that (PhSe)2 showed virucidal and antiviral actions reducing infectivity in 70.8% and 47%, respectively. The antiviral action of (PhSe)2 against HSV-2 vaginal infection was performed by infecting mice (10(5)  PFU/ml(-1) ) at day 6. The treatment with (PhSe)2 (5 mg/kg/day, intragastric [i.g.]) followed 5 days before and for more 5 days after infection. The extravaginal lesion score was evaluated from days 6 to 10. At day 11, animals were killed, and histological evaluation, determination of viral load, and TNF-α and IFN-γ levels were performed in supernatants of homogenized vaginal tissue. The levels of reactive species (RS), protein carbonyl, non-protein thiols (NPSH), nitrate/nitrite (NOx), and malondialdehyde (MDA), and the activities of myeloperoxidase (MPO), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) were determined. (PhSe)2 reduced the histological damage, extravaginal lesion scores, the viral load of vaginal tissue, and the activity of MPO, but increased the levels of TNF-α, IFN-γ. (PhSe)2 attenuated the increase of RS, MDA, NOx levels and the activity of GR caused by infection. (PhSe)2 also attenuated the reduction of NPSH content and the inhibition of CAT, SOD, and GPx activities. The antiviral action of (PhSe)2 against HSV-2 infection was related to its immunomodulatory, antioxidant, and anti-inflammatory properties. J. Cell. Biochem. 117: 1638-1648, 2016. © 2015 Wiley Periodicals, Inc.

Basal Autophagy Is Required for Herpes simplex Virus-2 Infection

Autophagy is a conserved catabolic process of the cell, which plays an important role in regulating plethora of infections. The role of autophagy in Herpes simplex virus-2 (HSV-2) infection is unknown. Here, we found that HSV-2 does not allow induction of an autophagic response to infection, but maintains basal autophagy levels mostly unchanged during productive infection. Thus, we investigated the importance of basal autophagy for HSV-2 infection, using pharmacological autophagy suppression or cells genetically deficient in an autophagy-essential gene (ATG5). Interference with basal autophagy flux in cells significantly reduced viral replication and diminished the infection. These results indicate that basal autophagy plays an indispensable role required for a productive infection. Importantly, this study draws a sharp distinction between induced and basal autophagy, where the former acts as a viral clearance mechanism abrogating infection, while the latter supports infection.

Hydrogen Peroxide Induce Human Cytomegalovirus Replication through the Activation of p38-MAPK Signaling Pathway

Human cytomegalovirus (HCMV) is a major risk factor in transplantation and AIDS patients, which induces high morbidity and mortality. These patients infected with HCMV experience an imbalance of redox homeostasis that cause accumulation of reactive oxygen species (ROS) at the cellular level. H₂O₂, the most common reactive oxygen species, is the main byproduct of oxidative metabolism. However, the function of H₂O₂ on HCMV infection is not yet fully understood and the effect and mechanism of N-acetylcysteine (NAC) on H₂O₂-stimulated HCMV replication is unclear. We, therefore, examined the effect of NAC on H₂O₂-induced HCMV production in human foreskin fibroblast cells. In the present study, we found that H₂O₂ enhanced HCMV lytic replication through promoting major immediate early (MIE) promoter activity and immediate early (IE) gene transcription. Conversely, NAC inhibited H₂O₂-upregulated viral IE gene expression and viral replication. The suppressive effect of NAC on CMV in an acute CMV-infected mouse model also showed a relationship between antioxidants and viral lytic replication. Intriguingly, the enhancement of HCMV replication via supplementation with H₂O₂ was accompanied with the activation of the p38 mitogen-activated protein kinase pathway. Similar to NAC, the p38 inhibitor SB203580 inhibited H₂O₂-induced p38 phosphorylation and HCMV upregulation, while upregulation of inducible ROS was unaffected. These results directly relate HCMV replication to H₂O₂, suggesting that treatment with antioxidants may be an attractive preventive and therapeutic strategy for HCMV.

Herpes simplex virus type 1 infection in neurons leads to production and nuclear localization of APP intracellular domain (AICD): implications for Alzheimer's disease pathogenesis

Several data indicate that neuronal infection with herpes simplex virus type 1 (HSV-1) causes biochemical alterations reminiscent of Alzheimer's disease (AD) phenotype. They include accumulation of amyloid-β (Aβ), which originates from the cleavage of amyloid precursor protein (APP), and hyperphosphorylation of tau protein, which leads to neurofibrillary tangle deposition. HSV-1 infection triggers APP processing and drives the production of several fragments including APP intracellular domain (AICD) that exerts transactivating properties. Herein, we analyzed the production and intracellular localization of AICD following HSV-1 infection in neurons. We also checked whether AICD induced the transcription of two target genes, neprilysin (nep) and glycogen synthase kinase 3β (gsk3β), whose products play a role in Aβ clearance and tau phosphorylation, respectively. Our data indicate that HSV-1 led to the accumulation and nuclear translocation of AICD in neurons. Moreover, results from chromatin immunoprecipitation assay showed that AICD binds the promoter region of both nep and gsk3β. Time course analysis of NEP and GSK3β expression at both mRNA and protein levels demonstrated that they are differently modulated during infection. NEP expression and enzymatic activity were initially stimulated but, with the progression of infection, they were down-regulated. In contrast, GSK3β expression remained nearly unchanged, but the analysis of its phosphorylation suggests that it was inactivated only at later stages of HSV-1 infection. Thus, our data demonstrate that HSV-1 infection induces early upstream events in the cell that may eventually lead to Aβ deposition and tau hyperphosphorylation and further suggest HSV-1 as a possible risk factor for AD.

Newcastle disease virus (NDV) induces protein oxidation and nitration in brain and liver of chicken: Ameliorative effect of vitamin E

The present study was aimed at investigating the therapeutic efficacy of vitamin E on oxidative injury in brain and liver of Newcastle disease virus (NDV) challenged chickens. We have analyzed the xanthine oxidase (XOD) activity; uric acid (UA) levels and superoxide radical generation by using electron spin resonance spectroscopy. Further, protein oxidation, nitration and apoptosis were evaluated in the brain and liver of the control, NDV-infected and NDV+Vit. E treated groups. A significant elevation was observed in XOD activity and UA levels in brain (p<0.001) and liver (p<0.05) of NDV infected birds when compared to controls. Further, significant increase in the production of superoxides, enhanced intracellular protein carbonyls and nitrates were observed in the brain and liver of NDV-infected birds over healthy subjects. Apoptosis studies also suggested that a larger number of TUNEL positive cells were observed in brain and a moderately in liver of NDV-infected chickens. However, all these perturbations were significantly ameliorated in NDV+Vit. E treated chickens as compared to NDV-infected birds. Taken together, our results suggested that NDV-induced neuronal and hepatic damage at least in part mediates oxidative stress and on the other hand, supplementation of vitamin E mitigates NDV-induced oxidative damage thereby protects brain and liver of chickens. These findings could provide new insights into the understanding of NDV pathogenesis and therapeutic effects of dietary antioxidants.