Subversion of the Heme Oxygenase-1 Antiviral Activity by Zika Virus

Zika virus restriction of host antioxidant response is mediated by intracellular NS1 and reveals its ability to upregulate Bach1 expression

Zika virus (ZIKV), has gained global attention due to its association with severe disorders, including microcephaly and congenital Zika syndrome. We investigated the role of ZIKV nonstructural protein 1 (NS1) in altering the host's antioxidant response. Using a stable cell line expressing NS1, we found that NS1 significantly reduced the expression of antioxidant-related genes, including heme oxygenase 1 (HO-1), NAD(P)H quinone dehydrogenase 1 (NQO1), and sequestosome-1 (SQSTM1), which are regulated NRF2. Interestingly, this effect was attributed to increased expression of BACH1, a factor that competes with NRF2 for binding to certain antioxidant responsive elements (ARE). Thus, ZIKV NS1-mediated disruption of the antioxidant system is linked to BACH1 overexpression. These findings offer insights into ZIKV pathogenesis and suggest potential therapeutic strategies targeting the NRF2-BACH1 axis.

The Antiviral Potential of AdipoRon, an Adiponectin Receptor Agonist, Reveals the Ability of Zika Virus to Deregulate Adiponectin Receptor Expression

Zika virus (ZIKV) is a pathogenic member of the flavivirus family, with several unique characteristics. Unlike any other arbovirus, ZIKV can be transmitted sexually and maternally, and thus produce congenital syndromes (CZS) due to its neurotropism. This challenges the search for safe active molecules that can protect pregnant women and their fetuses. In this context, and in the absence of any existing treatment, it seemed worthwhile to test whether the known cytoprotective properties of adiponectin and its pharmacological analog, AdipoRon, could influence the outcome of ZIKV infection. We showed that both AdipoRon and adiponectin could significantly reduce the in vitro infection of A549 epithelial cells, a well-known cell model for flavivirus infection studies. This effect was particularly observed when a pre-treatment was carried out. Conversely, ZIKV revealed an ability to downregulate adiponectin receptor expression and thereby limit adiponectin signaling.

Cobalt Protoporphyrin Blocks EqHV-8 Infection via IFN-α/β Production

Equid alphaherpesvirus type 8 (EqHV-8) is the causative agent of severe respiratory disease, abortions, and neurological syndromes in equines and has resulted in huge economic losses to the donkey industry. Currently, there exist no therapeutic molecules for controlling EqHV-8 infection. We evaluated the potential antiviral activity of cobalt protoporphyrin (CoPP) against EqHV-8 infection. Our results demonstrated that CoPP inhibited EqHV-8 infection in susceptible cells and mouse models. Furthermore, CoPP blocked the replication of EqHV-8 via HO-1 (heme oxygenase-1) mediated type I interferon (IFN) response. In conclusion, our data suggested that CoPP could serve as a novel potential molecule to develop an effective therapeutic strategy for EqHV-8 prevention and control.

Heme binding to the SARS-CoV-2 spike glycoprotein

The target for humoral immunity, SARS-CoV-2 spike glycoprotein, has become the focus of vaccine research and development. Previous work demonstrated that the N-terminal domain (NTD) of SARS-CoV-2 spike binds biliverdin-a product of heme catabolism-causing a strong allosteric effect on the activity of a subset of neutralizing antibodies. Herein, we show that the spike glycoprotein is also able to bind heme (KD = 0.5 ± 0.2 μM). Molecular modeling indicated that the heme group fits well within the same pocket on the SARS-CoV-2 spike NTD. Lined by aromatic and hydrophobic residues (W104, V126, I129, F192, F194, I203, and L226), the pocket provides a suitable environment to stabilize the hydrophobic heme. Mutagenesis of N121 has a substantive effect on heme binding (KD = 3000 ± 220 μM), confirming the pocket as a major heme binding location of the viral glycoprotein. Coupled oxidation experiments in the presence of ascorbate indicated that the SARS-CoV-2 glycoprotein can catalyze the slow conversion of heme to biliverdin. The heme trapping and oxidation activities of the spike may allow the virus to reduce levels of free heme during infection to facilitate evasion of the adaptive and innate immunity.

Heme Oxygenase-1 and Its Metabolites Carbon Monoxide and Biliverdin, but Not Iron, Exert Antiviral Activity against Porcine Circovirus Type 3

Porcine circovirus type 3 (PCV3) is a newly discovered pathogen that causes porcine dermatitis and nephropathy syndrome (PDNS)-like clinical signs, multisystemic inflammation, and reproductive failure. Heme oxygenase-1 (HO-1), a stress-inducible enzyme, exerts protective functions by converting heme into carbon monoxide (CO), biliverdin (BV), and iron. However, the effects of HO-1 and its metabolites on PCV3 replication remain unknown. In this study, experiments involving specific inhibitors, lentivirus transduction, and small interfering RNA (siRNA) transfection revealed that active PCV3 infection reduced HO-1 expression and that the expression of HO-1 negatively regulated virus replication in cultured cells, depending on its enzymatic activity. Subsequently, the effects of the HO-1 metabolites (CO, BV, and iron) on PCV3 infection were investigated. The CO inducers (cobalt protoporphyrin IX [CoPP] or tricarbonyl dichloro ruthenium [II] dimer [CORM-2]) mediate PCV3 inhibition by generating CO, and this inhibition is reversed by hemoglobin (Hb; a CO scavenger). The inhibition of PCV3 replication by BV depended on BV-mediated reactive oxygen species (ROS) reduction, as N-acetyl-l-cysteine affected PCV3 replication while reducing ROS production. The reduction product of BV, bilirubin (BR), specifically promoted nitric oxide (NO) generation and further activated the cyclic GMP/protein kinase G (cGMP/PKG) pathway to attenuate PCV3 infection. Both the iron provided by FeCl3 and the iron chelated by deferoxamine (DFO) with CoPP treatment failed to affect PCV3 replication. Our data demonstrate that the HO-1-CO-cGMP/PKG, HO-1-BV-ROS, and HO-1-BV-BR-NO-cGMP/PKG pathways contribute crucially to the inhibition of PCV3 replication. These results provide important insights regarding preventing and controlling PCV3 infection. IMPORTANCE The regulation of host protein expression by virus infection is the key to facilitating self-replication. As an important emerging pathogen of swine, clarification of the interaction between PCV3 infection and the host enables us to understand the viral life cycle and pathogenesis better. Heme oxygenase-1 (HO-1) and its metabolites carbon monoxide (CO), biliverdin (BV), and iron have been demonstrated to involve a wealth of viral replications. Here, we, for the first time, demonstrated that HO-1 expression decreases in PCV3-infected cells and negatively regulates PCV3 replication and that the HO-1 metabolic products CO and BV inhibit PCV3 replication by the CO- or BV/BR/NO-dependent cGMP/PKG pathway or BV-mediated ROS reduction, but the iron (the third metabolic product) does not. Specifically, PCV3 infection maintains normal proliferation by downregulating HO-1 expression. These findings clarify the mechanism by which HO-1 modulates PCV3 replication in cells and provide important targets for preventing and controlling PCV3 infection.

Caffeic Acid Has Antiviral Activity against Ilhéus Virus In Vitro

Ilhéus virus (ILHV) is a neglected mosquito-borne flavivirus. ILHV infection may lead to Ilhéus fever, an emerging febrile disease like dengue fever with the potential to evolve into a severe neurological disease characterized by meningoencephalitis; no specific treatments are available for this disease. This study assessed the antiviral properties of caffeic acid, an abundant component of plant-based food products that is also compatible with the socioeconomic limitations associated with this neglected infectious disease. The in vitro activity of caffeic acid on ILHV replication was investigated in Vero and A549 cell lines using plaque assays, quantitative RT-PCR, and immunofluorescence assays. We observed that 500 µM caffeic acid was virucidal against ILHV. Molecular docking indicated that caffeic acid might interact with an allosteric binding site on the envelope protein.

Hepatitis A: Viral Structure, Classification, Life Cycle, Clinical Symptoms, Diagnosis Error, and Vaccination

Hepatitis A virus (HAV) is one of the well-known viruses that cause hepatitis all around the globe. Although this illness has decreased in developed countries due to extensive immunization, numerous developing and under-developed countries are struggling with this virus. HAV infection can be spread by oral-fecal contact, and there are frequent epidemics through nutrition. Improvements in socioeconomic and sanitary circumstances have caused a shift in the disease's prevalence worldwide. Younger children are usually asymptomatic, but as they become older, the infection symptoms begin to appear. Symptoms range from slight inflammation and jaundice to acute liver failure in older individuals. While an acute infection may be self-limiting, unrecognized persistent infections, and the misapplication of therapeutic methods based on clinical guidelines are linked to a higher incidence of cirrhosis, hepatocellular carcinoma, and mortality. Fortunately, most patients recover within two months of infection, though 10-15% of patients will relapse within the first six months. A virus seldom leads to persistent infection or liver damage. The mainstay of therapy is based on supportive care. All children from 12-23 months, as well as some susceptible populations, should receive routine vaccinations, according to the Centers for Disease Control and Prevention and the American Academy of Pediatrics. Laboratory diagnosis of HAV is based on antigen detection, checking liver enzyme levels, and antibody screening. Furthermore, polymerase chain reaction (PCR) technology has identified HAV in suspected nutrition sources; therefore, this technique is used for preventative measures and food-related laws.

Analysis of fluoro based pyrazole analogues as a potential therapeutics candidate against Japanese encephalitis virus infection

Japanese encephalitis virus (JEV) is the leading causative agent of encephalitis and its associated mortality among children. JEV modulates host cell machinery for its advantage, such as oxidative damage which subsequently leads to stress responsive pathways. The present study analyzes new series of dinitroaryl substituted derivatives (1a-1f), containing pyrazole moiety and explores its potential ensuing anti-JEV activity. Out of all synthesized derivatives, compounds 1b and 1f were selected based on minimal cytotoxicity. In vitro inhibition of more than 70% and 90% were observed with compounds 1b and 1f, respectively, in neuronal cells. Dose-response analyses highlighted 1f exhibiting better antiviral activity than 1b. The mice treated with compound 1b or 1f did not show any noticeable toxicity at a dose of 100mg/kg/day when administered intraperitoneally till 96th h. Inhibition of up to 41% and 70% JEV mRNA in spleen and 33% to 43% in brain tissue was observed with compounds 1b and 1f, respectively. Both the compounds suppressed JEV induced ROS generation by up-regulating the NQO1 and HO-1 proteins. Our result suggests the interlocked positive feedback loops of NRF2-SQSTM1 signaling pathway to be regulated by the synthesized compounds. The potential of these compounds can be further tested for broad-spectrum antiviral effects with other flaviviruses in the path towards the development of therapeutics.

A Randomized Phase 2 Study of 5-Aminolevulinic Acid Hydrochloride and Sodium Ferrous Citrate for the Prevention of Nephrotoxicity Induced by Cisplatin-Based Chemotherapy of Lung Cancer

INTRODUCTION

Cisplatin-based chemotherapy was established in the 1980s, and it has been improved by the development of a short hydration protocol in lung cancer therapy. However, cisplatin-based chemotherapy is still associated with renal toxicity. Because 5-aminolevulinic acid (5-ALA) with sodium ferrous citrate (SFC) is known to be a mitochondrial activator and a heme oxygenase-1 (HO-1) inducer, 5-ALA with SFC is speculated to mitigate cisplatin-induced renal inflammation.

METHODS

We investigated the effects of oral administration of 5-ALA with SFC for preventing cisplatin-based nephrotoxicity in patients with lung cancer and evaluated its benefits for patients who received cisplatin-based chemotherapy. The primary endpoint was the significance of the difference between the serum creatinine (sCr) levels of the patients administered 5-ALA with SFC and those given placebo after course 1 of chemotherapy. The difference in the estimated glomerular filtration rate (eGFR) between the two groups was also evaluated as the secondary endpoint.

RESULTS

The double-blind, randomized two-arm studies were conducted at 15 medical facilities in Japan; 54 male and 20 female patients with lung cancer who received cisplatin-based chemotherapy between the ages of 42 and 75 years were included in the study. The compliance rate was greater than 94% in the primary assessment and subsequent drug administration periods. All enrolled patients completed the four cycles of cisplatin-based chemotherapy with short hydration. The average level of sCr on day 22 of course 1 was 0.707 mg/dL in the group treated with 5-ALA and SFC and 0.735 mg/dL in the placebo group, respectively, and the sCr in the test group was significantly lower than that in the placebo group (p = 0.038). In addition, the eGFR was significantly higher in the SPP-003 group than in the placebo group up to day 1 of course 3 (84.66 and 75.68 mL/min/1.73 m2, respectively, p = 0.02) and kept better even after the last administration of the study drug (82.37 and 73.49 mL/min/1.73 m2, respectively, p = 0.013).

CONCLUSIONS

The oral administration of 5-ALA with SFC is beneficial to patients undergoing cisplatin-based chemotherapy for lung cancer with short hydration.

Impact of CHIKV Replication on the Global Proteome of Aedes albopictus Cells

Arboviruses are some of the important causative agents of mosquito-mediated viral diseases. These viruses are transmitted between vector and host during the blood meal. Upon viral entry, host replication machinery is hijacked, supporting new virus particle production and thereby allowing viral survival in the host. In this process, host proteins interact with viral proteins to either facilitate viral replication, or they may provide antiviral defense mechanisms. In this study, we analyzed the impact of chikungunya virus (CHIKV) infection on the global proteome of Dicer active Aedes albopictus cells during the early and late time points of infection. We utilized a bottom-up approach of global proteomics analysis, and we used label-free quantitative mass spectrometry to identify the global protein signatures of Ae. albopictus at two different time points upon CHIKV infection. The mass spectrometry data analysis of the early time point revealed that proteins belonging to pathways such as translation, RNA processing, and cellular metabolic processes were less in abundance, whereas those belonging to pathways such as cellular catabolic process and organic substance transport were significantly abundant. At later time points, proteins belonging to pathways such as cellular metabolic processes, primary metabolic process, organonitrogen compound metabolic process, and organic substance metabolic process were found to be decreased in their presence, whereas those belonging to pathways such as RNA processing, gene expression, macromolecule metabolic processing, and nitrogen compound metabolic processing were found to be abundant during CHIKV infection, indicating that modulation in gene expression favoring cell survival occurs at a later time point, suggesting a survival strategy of Aedes cells to counter prolonged CHIKV infection.

COVID-19 metabolism: Mechanisms and therapeutic targets

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) dysregulates antiviral signaling, immune response, and cell metabolism in human body. Viral genome and proteins hijack host metabolic network to support viral biogenesis and propagation. However, the regulatory mechanism of SARS‐CoV‐2‐induced metabolic dysfunction has not been elucidated until recently. Multiomic studies of coronavirus disease 2019 (COVID‐19) revealed an intensive interaction between host metabolic regulators and viral proteins. SARS‐CoV‐2 deregulated cellular metabolism in blood, intestine, liver, pancreas, fat, and immune cells. Host metabolism supported almost every stage of viral lifecycle. Strikingly, viral proteins were found to interact with metabolic enzymes in different cellular compartments. Biochemical and genetic assays also identified key regulatory nodes and metabolic dependencies of viral replication. Of note, cholesterol metabolism, lipid metabolism, and glucose metabolism are broadly involved in viral lifecycle. Here, we summarized the current understanding of the hallmarks of COVID‐19 metabolism. SARS‐CoV‐2 infection remodels host cell metabolism, which in turn modulates viral biogenesis and replication. Remodeling of host metabolism creates metabolic vulnerability of SARS‐CoV‐2 replication, which could be explored to uncover new therapeutic targets. The efficacy of metabolic inhibitors against COVID‐19 is under investigation in several clinical trials. Ultimately, the knowledge of SARS‐CoV‐2‐induced metabolic reprogramming would accelerate drug repurposing or screening to combat the COVID‐19 pandemic.

Increase of HO-1 Expression in Critically Ill COVID-19 Patients Is Associated with Poor Prognosis and Outcome

Heme-oxygenase (HO)-1 is a cytoprotective enzyme with strong antioxidant and anti-apoptotic properties and previous reports have also emphasized the antiviral properties of HO-1, either directly or via induction of interferons. To investigate the potential role of HO-1 in patients with coronavirus disease 2019 (COVID-19), the present study assessed changes in HO-1 expression in whole blood and tissue samples. Upregulation of HO-1 protein was observed in lung, liver, and skin tissue independently of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presence. A significant increase of blood HO-1 mRNA levels was observed in critically ill COVID-19 patients compared to those in severe COVID-19 patients and healthy controls. This increase was accompanied by significantly elevated levels of serum ferritin and bilirubin in critically ill compared to patients with severe disease. Further grouping of patients in survivors and non-survivors revealed a significant increase of blood HO-1 mRNA levels in the later. Receiver operating characteristic (ROC) analysis for prediction of ICU admission and mortality yielded an AUC of 0.705 (p = 0.016) and 0.789 (p = 0.007) respectively indicating that HO-1 increase is associated with poor COVID-19 progression and outcome. The increase in HO-1 expression observed in critically ill COVID-19 patients could serve as a mechanism to counteract increased heme levels driving coagulation and thrombosis or as an induced protective mechanism.

Transcriptional and Translational Dynamics of Zika and Dengue Virus Infection

Zika virus (ZIKV) and dengue virus (DENV) are members of the Flaviviridae family of RNA viruses and cause severe disease in humans. ZIKV and DENV share over 90% of their genome sequences, however, the clinical features of Zika and dengue infections are very different reflecting tropism and cellular effects. Here, we used simultaneous RNA sequencing and ribosome footprinting to define the transcriptional and translational dynamics of ZIKV and DENV infection in human neuronal progenitor cells (hNPCs). The gene expression data showed induction of aminoacyl tRNA synthetases (ARS) and the translation activating PIM1 kinase, indicating an increase in RNA translation capacity. The data also reveal activation of different cell stress responses, with ZIKV triggering a BACH1/2 redox program, and DENV activating the ATF/CHOP endoplasmic reticulum (ER) stress program. The RNA translation data highlight activation of polyamine metabolism through changes in key enzymes and their regulators. This pathway is needed for eIF5A hypusination and has been implicated in viral translation and replication. Concerning the viral RNA genomes, ribosome occupancy readily identified highly translated open reading frames and a novel upstream ORF (uORF) in the DENV genome. Together, our data highlight both the cellular stress response and the activation of RNA translation and polyamine metabolism during DENV and ZIKV infection.

Balanced cytokine upregulation by diluted ethanolic extract of Bryonia alba in Delta SARS-CoV-2 Spike protein RBD-induced pathogenesis in Gallus gallus embryo

BACKGROUND

Bryonia alba extract is a well-known drug which is being utilized as phytomedicines and homoeopathic preparations since more than two centuries. This medicine is frequently used in clinical practice for flu-like conditions, respiratory tract infections, and gastrointestinal diseases, as evidenced by old literature and historical records. The plant contains Bryonicin, Bryonolic acid, Bryodin, Cucurbitacin, etc. The alkaloids in Bryonia alba have been discovered to be a powerful heme-oxygenase-1 inhibitor, which could help reduce oxidative stress during SARS-CoV-2 pathogenesis. During three waves of SARS-CoV-2, extracts of Bryonia alba were used; however, the actual scientific explanation for its mechanism of action is still unknown. In this experiment, we studied cytokine changes by diluted Bryonia alba extract in Delta SARS-CoV-2 spike protein RBD-induced pathogenesis, in fertilized chick (Gallus gallus domesticus) embryos.

RESULTS

The recombinant Delta SARS-CoV-2 spike RBD protein was inoculated in 14-day-old chick (Gallus gallus domesticus) embryos along with control, pre-, and post-treatment sets with diluted Bryonia extract. After 48 h, allantoic fluids were collected and stored at - 20 °C for study of different cytokines. Histological changes of the liver were also studied in each animal. Diluted Bryonia extract upregulated IFN-α and IL-10 markedly. In pre-treatment set, IFN-α, IL-8, IL-10, and IL-1β were markedly decreased, while in the post-treatment set IL-6, IL-10, IL-8, and TGFβ1 were significantly decreased, with a tendency of more anti-inflammatory surge than pro-inflammatory cytokines.

CONCLUSIONS

This experiment indicated an immunomodulatory role of diluted ethanolic extract of Bryonia particularly in the post-treatment set, decreasing pro-inflammatory cytokines with beneficial effect.

A Journey into the Clinical Relevance of Heme Oxygenase 1 for Human Inflammatory Disease and Viral Clearance: Why Does It Matter on the COVID-19 Scene?

Heme oxygenase 1 (HO-1), the rate-limiting enzyme in heme degradation, is involved in the maintenance of cellular homeostasis, exerting a cytoprotective role by its antioxidative and anti-inflammatory functions. HO-1 and its end products, biliverdin, carbon monoxide and free iron (Fe²⁺), confer cytoprotection against inflammatory and oxidative injury. Additionally, HO-1 exerts antiviral properties against a diverse range of viral infections by interfering with replication or activating the interferon (IFN) pathway. Severe cases of coronavirus disease 2019 (COVID-19), an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are characterized by systemic hyperinflammation, which, in some cases, leads to severe or fatal symptoms as a consequence of respiratory failure, lung and heart damage, kidney failure, and nervous system complications. This review summarizes the current research on the protective role of HO-1 in inflammatory diseases and against a wide range of viral infections, positioning HO-1 as an attractive target to ameliorate clinical manifestations during COVID-19.

Hemin as a novel candidate for treating COVID-19 via heme oxygenase-1 induction

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the coronavirus disease-19 (COVID-19). More than 143 million cases of COVID-19 have been reported to date, with the global death rate at 2.13%. Currently, there are no licensed therapeutics for controlling SARS-CoV-2 infection. The antiviral effects of heme oxygenase-1 (HO-1), a cytoprotective enzyme that inhibits the inflammatory response and reduces oxidative stress, have been investigated in several viral infections. To confirm whether HO-1 suppresses SARS-CoV-2 infection, we assessed the antiviral activity of hemin, an effective and safe HO-1 inducer, in SARS-CoV-2 infection. We found that treatment with hemin efficiently suppressed SARS-CoV-2 replication (selectivity index: 249.7012). Besides, the transient expression of HO-1 using an expression vector also suppressed the growth of the virus in cells. Free iron and biliverdin, which are metabolic byproducts of heme catalysis by HO-1, also suppressed the viral infection. Additionally, hemin indirectly increased the expression of interferon-stimulated proteins known to restrict SARS-CoV-2 replication. Overall, the findings suggested that HO-1, induced by hemin, effectively suppressed SARS-CoV-2 in vitro. Therefore, HO-1 could be potential therapeutic candidate for COVID-19.

Nrf2 activator PB125® as a carnosic acid-based therapeutic agent against respiratory viral diseases, including COVID-19

PB125® is a phytochemical composition providing potent Nrf2 activation as well as a number of direct actions that do not involve Nrf2. Nrf2 is a transcription actor that helps maintain metabolic balance by providing redox-sensitive expression of numerous genes controlling normal day-to-day metabolic pathways. When ordinary metabolism is upset by extraordinary events such as injury, pathogenic infection, air or water pollution, ingestion of toxins, or simply by the slow but incessant changes brought about by aging and genetic variations, Nrf2 may also be called into action by the redox changes resulting from these events, whether acute or chronic. A complicating factor in all of this is that Nrf2 levels decline with aging, leaving the elderly less able to maintain proper redox balance. The dysregulated gene expression that results can cause or exacerbate a wide variety of pathological conditions, including susceptibility to viral infections. This review examines the characteristics desirable in Nrf2 activators that have therapeutic potential, as well as some of the patterns of dysregulated gene expression commonly observed during pulmonary infections and the normalizing effects possible by judicious use of phytochemicals to increase the activation level of available Nrf2.

Resveratrol as an Adjunctive Therapy for Excessive Oxidative Stress in Aging COVID-19 Patients

The coronavirus disease 2019 (COVID-19) pandemic continues to burden healthcare systems worldwide. COVID-19 symptoms are highly heterogeneous, and the patient may be asymptomatic or may present with mild to severe or fatal symptoms. Factors, such as age, sex, and comorbidities, are key determinants of illness severity and progression. Aging is accompanied by multiple deficiencies in interferon production by dendritic cells or macrophages in response to viral infections, resulting in dysregulation of inflammatory immune responses and excess oxidative stress. Age-related dysregulation of immune function may cause a more obvious pathophysiological response to SARS-CoV-2 infection in elderly patients and may accelerate the risk of biological aging, even after recovery. For more favorable treatment outcomes, inhibiting viral replication and dampening inflammatory and oxidative responses before induction of an overt cytokine storm is crucial. Resveratrol is a potent antioxidant with antiviral activity. Herein, we describe the reasons for impaired interferon production, owing to aging, and the impact of aging on innate and adaptive immune responses to infection, which leads to inflammation distress and immunosuppression, thereby causing fulminant disease. Additionally, the molecular mechanism by which resveratrol could reverse a state of excessive basal inflammatory and oxidative stress and low antiviral immunity is discussed.

SARS-CoV-2 Proteins Bind to Hemoglobin and Its Metabolites

(1) Background: coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been linked to hematological dysfunctions, but there are little experimental data that explain this. Spike (S) and Nucleoprotein (N) proteins have been putatively associated with these dysfunctions. In this work, we analyzed the recruitment of hemoglobin (Hb) and other metabolites (hemin and protoporphyrin IX-PpIX) by SARS-Cov2 proteins using different approaches. (2) Methods: shotgun proteomics (LC-MS/MS) after affinity column adsorption identified hemin-binding SARS-CoV-2 proteins. The parallel synthesis of the peptides technique was used to study the interaction of the receptor bind domain (RBD) and N-terminal domain (NTD) of the S protein with Hb and in silico analysis to identify the binding motifs of the N protein. The plaque assay was used to investigate the inhibitory effect of Hb and the metabolites hemin and PpIX on virus adsorption and replication in Vero cells. (3) Results: the proteomic analysis by LC-MS/MS identified the S, N, M, Nsp3, and Nsp7 as putative hemin-binding proteins. Six short sequences in the RBD and 11 in the NTD of the spike were identified by microarray of peptides to interact with Hb and tree motifs in the N protein by in silico analysis to bind with heme. An inhibitory effect in vitro of Hb, hemin, and PpIX at different levels was observed. Strikingly, free Hb at 1mM suppressed viral replication (99%), and its interaction with SARS-CoV-2 was localized into the RBD region of the spike protein. (4) Conclusions: in this study, we identified that (at least) five proteins (S, N, M, Nsp3, and Nsp7) of SARS-CoV-2 recruit Hb/metabolites. The motifs of the RDB of SARS-CoV-2 spike, which binds Hb, and the sites of the heme bind-N protein were disclosed. In addition, these compounds and PpIX block the virus's adsorption and replication. Furthermore, we also identified heme-binding motifs and interaction with hemin in N protein and other structural (S and M) and non-structural (Nsp3 and Nsp7) proteins.

Cerebral Organoids Derived from a Parkinson's Patient Exhibit Unique Pathogenesis from Chikungunya Virus Infection When Compared to a Non-Parkinson's Patient

(1) Background: Arboviruses of medical and veterinary significance have been identified on all seven continents, with every human and animal population at risk for exposure. Like arboviruses, chronic neurodegenerative diseases, like Alzheimer’s and Parkinson’s disease, are found wherever there are humans. Significant differences in baseline gene and protein expression have been determined between human-induced pluripotent stem cell lines derived from non-Parkinson’s disease individuals and from individuals with Parkinson’s disease. It was hypothesized that these inherent differences could impact cerebral organoid responses to viral infection. (2) Methods: In this study, cerebral organoids from a non-Parkinson’s and Parkinson’s patient were infected with Chikungunya virus and observed for two weeks. (3) Results: Parkinson’s organoids lost mass and exhibited a differential antiviral response different from non-Parkinson’s organoids. Neurotransmission data from both infected non-Parkinson’s and Parkinson’s organoids had dysregulation of IL-1, IL-10, and IL-6. These cytokines are associated with mood and could be contributing to persistent depression seen in patients following CHIKV infection. Both organoid types had increased expression of CXCL10, which is linked to demyelination. (4) Conclusions: The differential antiviral response of Parkinson’s organoids compared with non-Parkinson’s organoids highlights the need for more research in neurotropic infections in a neurologically compromised host.

Piperlongumine Inhibits Zika Virus Replication In vitro and Promotes Up-Regulation of HO-1 Expression, Suggesting An Implication of Oxidative Stress

Owing to the widespread distribution of mosquitoes capable of transmitting Zika virus, lack of clinical vaccines and treatments, and poor immunity of populations to new infectious diseases, Zika virus has become a global public health concern. Recent studies have found that Zika virus can continuously infect human brain microvascular endothelial cells. These cells are the primary components of the blood-brain barrier of the cerebral cortex, and further infection of brain tissue may cause severe damage such as encephalitis and fetal pituitary disease. The present study found that a biologically active base, piperlongumine (PL), inhibited Zika virus replication in human brain microvascular endothelial cells, Vero cells, and human umbilical vein endothelial cells. PL also significantly increased heme oxygenase-1 (HO-1) gene expression, while silencing HO-1 expression and using the reactive oxygen species scavenger, N-acetylcysteine, attenuated the inhibitory effect of PL on Zika virus replication. These results suggest that PL induces oxidative stress in cells by increasing reactive oxygen species. This, in turn, induces an increase in HO-1 expression, thereby inhibiting Zika virus replication. These findings provide novel clues for drug research on the prevention and treatment of Zika virus.

Could Oral Phosphodiesterase 5 Inhibitors Have a Potential Adjuvant Role in Combating COVID-19 Infection?

INTRODUCTION

The recent global outbreak of coronavirus disease 2019 (COVID-19) has become a pandemic with a lot of sufferers. Excessive inflammation, exaggerated immune response, with ultimate apoptosis contribute to COVID-19 pathology that progress to acute lung acute respiratory distress.

OBJECTIVE

To shed a light on the likely benefits of the oral phosphodiesterase 5 (PDE5) inhibitor adjuvant role in combating COVID-19 infection.

METHODS

A literature review was performed in the PubMed/Medline database, Scopus, Cochrane Library, EMBASE, Academic Search Complete, Google Scholar, and CINAHL databases using the keywords COVID-19; phosphodiesterase-5 inhibitors; cytokine storm; respiratory distress.

RESULTS

Despite the worsening trends of COVID-19, still no drugs are validated to have significant clinical efficacy in the treatment of patients with COVID-19 in large-scale studies. While the progress toward a curative agent and/or vaccine is certainly hopeful, the principal limiting factor in such public health emergencies is always the time. Therefore, a preexisting licensed therapeutic(s) might offer a reprieve to the healthcare systems operating at the edge of capacity. In this context, the innovation of oral PDE5 inhibitors with their valuable effects on erection have provided a breakthrough in the treatment of erectile dysfunction and opened new fields of clinical application for this class of drugs. Oral PDE5 inhibitors have been demonstrated to possess many beneficial useful additional implications with acknowledged anti-inflammatory, antioxidant, immune response regulation, and antiapoptotic properties. These properties have been elucidated through the nitric oxide/soluble guanylyl cyclase/cyclic guanylate monophosphate pathway in addition to the emerged hemeoxygenase-1 enzyme as well as hydrogen sulfide pathways. These properties could support repurposing oral PDE5 inhibitors' potential adjuvant use in targeting different aspects of COVID-19 infection.

CONCLUSION

Oral PDE5 inhibitors retain several acknowledged off-labeled useful implications with anti-inflammatory, antioxidant, immune response regulation, and antiapoptotic properties. These properties may support repurposing oral PDE5 inhibitors' potential adjuvant use in the protocols combating COVID-19 manifestations. Mostafa T. Could Oral Phosphodiesterase 5 Inhibitors Have a Potential Adjuvant Role in Combating Coronavirus Disease 2019 Infection? Sex Med Rev 2021;9:15-22.

Heme oxygenase-1 modulation: A potential therapeutic target for COVID-19 and associated complications

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to infect hundred thousands of people every day worldwide. Since it is a novel virus, research continues to update the possible therapeutic targets when new evidence regarding COVID-19 are gathered. This article presents an evidence-based hypothesis that activating the heme oxygenase-1 (HO-1) pathway is a potential target for COVID-19. Interferons (IFNs) have broad-spectrum antiviral activity including against SARS-CoV-2. Induction of HO-1 and increase in the heme catabolism end-product confer antiviral activity. IFN activation results in inhibition of viral replication in various viral infections. COVID-19 induced inflammation as well as acute respiratory distress syndrome (ARDS), and coagulopathies are now known major causes of mortality. A protective role of HO-1 induction in inflammation, inflammation-induced coagulation, and ARDS has been reported. Based on an association of HO-1 promoter polymorphisms and disease severity, we propose an evaluation of the status of these polymorphisms in COVID-19 patients who become severely ill. If an association is established, it might be helpful in identifying patients at high risk. Hence, we hypothesize that HO-1 pathway activation could be a therapeutic strategy against COVID-19 and associated complications.

Could Oral Phosphodiesterase 5 Inhibitors Have a Potential Adjuvant Role in Combating COVID-19 Infection?

INTRODUCTION

The recent global outbreak of coronavirus disease 2019 (COVID-19) has become a pandemic with a lot of sufferers. Excessive inflammation, exaggerated immune response, with ultimate apoptosis contribute to COVID-19 pathology that progress to acute lung acute respiratory distress.

OBJECTIVE

To shed a light on the likely benefits of the oral phosphodiesterase 5 (PDE5) inhibitor adjuvant role in combating COVID-19 infection.

METHODS

A literature review was performed in the PubMed/Medline database, Scopus, Cochrane Library, EMBASE, Academic Search Complete, Google Scholar, and CINAHL databases using the keywords COVID-19; phosphodiesterase-5 inhibitors; cytokine storm; respiratory distress.

RESULTS

Despite the worsening trends of COVID-19, still no drugs are validated to have significant clinical efficacy in the treatment of patients with COVID-19 in large-scale studies. While the progress toward a curative agent and/or vaccine is certainly hopeful, the principal limiting factor in such public health emergencies is always the time. Therefore, a preexisting licensed therapeutic(s) might offer a reprieve to the healthcare systems operating at the edge of capacity. In this context, the innovation of oral PDE5 inhibitors with their valuable effects on erection have provided a breakthrough in the treatment of erectile dysfunction and opened new fields of clinical application for this class of drugs. Oral PDE5 inhibitors have been demonstrated to possess many beneficial useful additional implications with acknowledged anti-inflammatory, antioxidant, immune response regulation, and antiapoptotic properties. These properties have been elucidated through the nitric oxide/soluble guanylyl cyclase/cyclic guanylate monophosphate pathway in addition to the emerged hemeoxygenase-1 enzyme as well as hydrogen sulfide pathways. These properties could support repurposing oral PDE5 inhibitors' potential adjuvant use in targeting different aspects of COVID-19 infection.

CONCLUSION

Oral PDE5 inhibitors retain several acknowledged off-labeled useful implications with anti-inflammatory, antioxidant, immune response regulation, and antiapoptotic properties. These properties may support repurposing oral PDE5 inhibitors' potential adjuvant use in the protocols combating COVID-19 manifestations. Mostafa T. Could Oral Phosphodiesterase 5 Inhibitors Have a Potential Adjuvant Role in Combating Coronavirus Disease 2019 Infection? Sex Med Rev 2021;9:15-22.

The role of host defences in Covid 19 and treatments thereof

Hydrogen sulfide (H₂S) is a natural defence against the infections from enveloped RNA viruses and is likely involved also in Covid 19. It was already shown to inhibit growth and pathogenic mechanisms of a variety of enveloped RNA viruses and it was now found that circulating H₂S is higher in Covid 19 survivors compared to fatal cases. H₂S release is triggered by carbon monoxide (CO) from the catabolism of heme by inducible heme oxygenase (HO-1) and heme proteins possess catalytic activity necessary for the H₂S signalling by protein persulfidation. Subjects with a long promoter for the HMOX1 gene, coding for HO-1, are predicted for lower efficiency of this mechanism. SARS-cov-2 exerts ability to attack the heme of hemoglobin and other heme-proteins thus hampering both release and signalling of H₂S. Lack of H₂S-induced persulfidation of the K_ATP channels of leucocytes causes adhesion and release of the inflammatory cytokines, lung infiltration and systemic endothelial damage with hyper-coagulability. These events largely explain the sex and age distribution, clinical manifestations and co-morbidities of Covid-19. The understanding of this mechanism may be of guidance in re-evaluating the ongoing therapeutic strategies, with special attention to the interaction with mechanical ventilation, paracetamol and chloroquine use, and in the individuation of genetic traits causing increased susceptibility to the disruption of these physiologic processes and to a critical Covid 19. Finally, an array of therapeutic interventions with the potential to clinically modulate the HO-1/CO/H₂S axis is already available or under development. These include CO donors and H₂S donors and a boost to the endogenous production of H₂S is also possible.

COVID-19 and heme oxygenase: novel insight into the disease and potential therapies

The COVID-19 pandemic needs therapies that are presently available and safe. We propose that subjects with metabolic syndrome, old age, and male gender have the greatest morbidity and mortality and have low stress proteins, in particular, low intracellular heme oxygenase (HO-1), making them particularly vulnerable to the disease. Additionally, COVID-19's heme reduction may contribute to even lower HO-1. Low-grade inflammation associated with these risk factors contributes to triggering a cytokine storm that spreads to multi-organ failure and near death. The high mortality of those treated with ventilator assistance may partially be explained by ventilator-induced inflammation. The cytoprotective and anti-inflammatory properties of HO-1 can limit the infection's damage. A paradox of COVID-19 hospital admissions data suggests that fewer cigarette-smokers are admitted compared with non-smokers in the general population. This unexpected observation may result from smoke induction of HO-1. Therapies with anti-viral properties that raise HO-1 include certain anesthetics (sevoflurane or isoflurane), hemin, estrogen, statins, curcumin, resveratrol, and melatonin. Controlled trials of these HO-1 inducers should be done in order to prevent or treat COVID-19 disease.

Nrf2 Activator PB125® as a Potential Therapeutic Agent against COVID-19

Nrf2 is a transcription factor that regulates cellular redox balance and the expression of a wide array of genes involved in immunity and inflammation, including antiviral actions. Nrf2 activity declines with age, making the elderly more susceptible to oxidative stress-mediated diseases, which include type 2 diabetes, chronic inflammation, and viral infections. Published evidence suggests that Nrf2 activity may regulate important mechanisms affecting viral susceptibility and replication. We examined gene expression levels by GeneChip microarray and by RNA-seq assays. We found that the potent Nrf2-activating composition PB125® downregulates ACE2 and TMPRSS2 mRNA expression in human liver-derived HepG2 cells. ACE2 is a surface receptor and TMPRSS2 activates the spike protein for SARS-CoV-2 entry into host cells. Furthermore, in endotoxin-stimulated primary human pulmonary artery endothelial cells, we report the marked downregulation by PB125 of 36 genes encoding cytokines. These include IL-1-beta, IL-6, TNF-α, the cell adhesion molecules ICAM-1, VCAM-1, and E-selectin, and a group of IFN-γ-induced genes. Many of these cytokines have been specifically identified in the "cytokine storm" observed in fatal cases of COVID-19, suggesting that Nrf2 activation may significantly decrease the intensity of the storm.

Nrf2 Activator PB125® as a Potential Therapeutic Agent Against COVID-19

Nrf2 is a transcription factor that regulates cellular redox balance and the expression of a wide array of genes involved in immunity and inflammation, including antiviral actions. Nrf2 activity declines with age, making the elderly more susceptible to oxidative stress-mediated diseases, which include type 2 diabetes, chronic inflammation, and viral infections. Published evidence suggests that Nrf2 activity may regulate important mechanisms affecting viral susceptibility and replication. We examined gene expression levels by GeneChip microarray and by RNA-seq assays. We found that the potent Nrf2 activating composition PB125® downregulates ACE2 and TMPRSS2 mRNA expression in human liver-derived HepG2 cells. ACE2 is a surface receptor and TMPRSS2 activates the spike protein for SARS-Cov-2 entry into host cells. Furthermore, in endotoxin-stimulated primary human pulmonary artery endothelial cells we report the marked downregulation by PB125 of 36 genes encoding cytokines. These include IL1-beta, IL6, TNF-α the cell adhesion molecules ICAM1, VCAM1, and E-selectin, and a group of IFN-γ-induced genes. Many of these cytokines have been specifically identified in the “cytokine storm” observed in fatal cases of COVID-19, suggesting that Nrf2 activation may significantly decrease the intensity of the storm.

Zika virus subversion of chaperone GRP78/BiP expression in A549 cells during UPR activation

Flaviviruses replicate in membranous factories associated with the endoplasmic reticulum (ER). Significant levels of flavivirus polyprotein integration contribute to ER stress and the host cell may exhibit an Unfolded Protein Response (UPR) to this protein accumulation, stimulating appropriate cellular responses such as adaptation, autophagy or cell death. These different stress responses support other antiviral strategies initiated by infected cells and can help to overcome viral infection. In epithelial A549 cells, a model currently used to study the flavivirus infection cycle and the host cell responses, all three pathways leading to UPR are activated during infection by Dengue virus (DENV), Yellow Fever virus (YFV) or West Nile virus (WNV). In the present study, we investigated the capacity of ZIKA virus (ZIKV) to induce ER stress in A549 cells. We observed that the cells respond to ZIKV infection by implementing an UPR through activation of the IRE1 and PERK pathway without activation of the ATF6 branch. By modulating the ER stress response, we found that UPR inducers significantly inhibit ZIKV replication. Interestingly, our findings provide evidence that ZIKV could manipulate the UPR to escape this host cell defence system by downregulating GRP78/BiP expression. This subversion of GRP78 expression could lead to unresolved and persistent ER stress which can be a benefit for virus growth.

EV71 virus reduces Nrf2 activation to promote production of reactive oxygen species in infected cells

BACKGROUND

Emerging evidence closely links Enterovirus 71 (EV71) infection with the generation of reactive oxygen species (ROS). Excess ROS results in apoptosis and exacerbates inflammatory reactions. The Keap1-Nrf2 axis serves as an essential oxidant counteracting pathway.

METHODS

The present study aimed to elucidate the role of the Keap1-Nrf2 pathway in modulating apoptosis and inflammatory reactions triggered by oxidative stress in Vero and RD cells upon EV71 infection.

RESULTS

Elevated ROS production was identified in EV71 infected Vero and RD cells. The percentage of dead cells and expression of inflammation-promoting cytokines were increased in these cells. EV71 infected cells also displayed reinforced Keap1 expression and abrogated Nrf2 expression. Keap1 silencing resulted in the downstream aggregation of the Nrf2 protein and heme oxygenase-1 HO-1. Keap1 silencing repressed ubiquitination and reinforced Nrf2 nuclear trafficking. Furthermore, silencing Keap1 expression repressed ROS production, cell death, and inflammatory reactions in EV71 infected RD and Vero cells. In contrast, silencing of both Keap1 and Nrf2 restored ROS production, cell death, and inflammatory reactions. Nrf2 and Keap1 modulated the stimulation of the Akt sensor and extrinsic as well as intrinsic cell death pathways, resulting in EV71-triggered cell death and inflammatory reactions.

CONCLUSIONS

EV71 infection can trigger ROS production, cell death, and inflammatory reactions by modulating the Nrf2 and Keap1 levels of infected cells.

Progressive Rotavirus Infection Downregulates Redox-Sensitive Transcription Factor Nrf2 and Nrf2-Driven Transcription Units

Eukaryotic cells adopt highly tuned stress response physiology under threats of exogenous stressors including viruses to maintain cellular homeostasis. Not surprisingly, avoidance of cellular stress response pathways is an essential facet of virus-induced obligatory host reprogramming to invoke a cellular environment conducive to viral perpetuation. Adaptive cellular responses to oxidative and electrophilic stress are usually taken care of by an antioxidant defense system, core to which lies the redox-responsive transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and Nrf2-driven transcriptional cascade. Deregulation of host redox balance and redox stress-sensitive Nrf2 antioxidant defense have been reported for many viruses. In the current study, we aimed to study the modulation of the Nrf2-based host cellular redox defense system in response to Rotavirus (RV) infection in vitro. Interestingly, we found that Nrf2 protein levels decline sharply with progression of RV infection beyond an initial upsurge. Moreover, Nrf2 decrease as a whole was found to be accompanied by active nuclear vacuity of Nrf2, resulting in lowered expression of stress-responsive Nrf2 target genes heme oxygenase-1 (HO-1), NAD(P)H quinone dehydrogenase 1, and superoxide dismutase 1 both in the presence and absence of Nrf2-driven transcriptional inducers. Initial induction of Nrf2 concurred with RV-induced early burst of oxidative stress and therefore was sensitive to treatments with antioxidants. Reduction of Nrf2 levels beyond initial hours, however, was found to be independent of the cellular redox status. Furthermore, increasing the half-life of Nrf2 through inhibition of the Kelch-like erythroid cell-derived protein with CNC homology- (ECH-) associated protein 1/Cullin3-RING Box1-based canonical Nrf2 turnover pathway could not restore Nrf2 levels post RV-SA11 infection. Depletion of the Nrf2/HO-1 axis was subsequently found to be sensitive to proteasome inhibition with concurrent observation of increased K48-linked ubiquitination associated with Nrf2. Together, the present study describes robust downregulation of Nrf2-dependent cellular redox defense beyond initial hours of RV infection, justifying our previous observation of potent antirotaviral implications of Nrf2 agonists.

Immune Evasion Strategies Used by Zika Virus to Infect the Fetal Eye and Brain

Zika virus (ZIKV) is a mosquito-transmitted flavivirus that caused a public health emergency in the Americas when an outbreak in Brazil became linked to congenital microcephaly. Understanding how ZIKV could evade the innate immune defenses of the mother, placenta, and fetus has become central to determining how the virus can traffic into the fetal brain. ZIKV, like other flaviviruses, evades host innate immune responses by leveraging viral proteins and other processes that occur during viral replication to allow spread to the placenta. Within the placenta, there are diverse cell types with coreceptors for ZIKV entry, creating an opportunity for the virus to establish a reservoir for replication and infect the fetus. The fetal brain is vulnerable to ZIKV, particularly during the first trimester, when it is beginning a dynamic process, to form highly complex and specialized regions orchestrated by neuroprogenitor cells. In this review, we provide a conceptual framework to understand the different routes for viral trafficking into the fetal brain and the eye, which are most likely to occur early and later in pregnancy. Based on the injury profile in human and nonhuman primates, ZIKV entry into the fetal brain likely occurs across both the blood/cerebrospinal fluid barrier in the choroid plexus and the blood/brain barrier. ZIKV can also enter the eye by trafficking across the blood/retinal barrier. Ultimately, the efficient escape of innate immune defenses by ZIKV is a key factor leading to viral infection. However, the host immune response against ZIKV can lead to injury and perturbations in developmental programs that drive cellular division, migration, and brain growth. The combined effect of innate immune evasion to facilitate viral propagation and the maternal/placental/fetal immune response to control the infection will determine the extent to which ZIKV can injure the fetal brain.

The ZIKA Virus Delays Cell Death Through the Anti-Apoptotic Bcl-2 Family Proteins

Zika virus (ZIKV) is an emerging human mosquito-transmitted pathogen of global concern, known to be associated with complications such as congenital defects and neurological disorders in adults. ZIKV infection is associated with induction of cell death. However, previous studies suggest that the virally induced apoptosis occurs at a slower rate compared to the course of viral production. In this present study, we investigated the capacity of ZIKV to delay host cell apoptosis. We provide evidence that ZIKV has the ability to interfere with apoptosis whether it is intrinsically or extrinsically induced. In cells expressing viral replicon-type constructions, we show that this control is achieved through replication. Finally, our work highlights an important role for anti-apoptotic Bcl-2 family protein in the ability of ZIKV to control apoptotic pathways, avoiding premature cell death and thereby promoting virus replication in the host-cell.

Molecular signatures associated with prostate cancer cell line (PC-3) exposure to inactivated Zika virus

The recent outbreak of Zika virus (ZIKV) infection associated with microcephaly cases has elicited much research on the mechanisms involved in ZIKV-host cell interactions. It has been described that Zika virus impairs cell growth, raising a hypothesis about its oncolytic potential against cancer cells. ZIKV tumor cell growth inhibition was later confirmed for glioblastoma. It was also demonstrated that an inactivated ZIKV prototype (ZVp) based on bacterial outer membrane vesicles has antiproliferative activity upon other cancer cell lines, such as PC-3 prostate cancer cell. This study aims at understanding the pathways that might be involved with the antiproliferative effect of Zika virus against prostate cancer cells. A metabolomic approach based on high-resolution mass spectrometry analysis led to the identification of 21 statistically relevant markers of PC-3 cells treated with ZVp. The markers were associated with metabolic alterations that trigger lipid remodeling, endoplasmic reticulum stress, inflammatory mediators, as well as disrupted porphyrin and folate metabolism. These findings highlight molecular signatures of ZVp-induced response that may be involved on cellular pathways triggered by its antiproliferative effect. To our knowledge, this is the first reported metabolomic assessment of ZIKV effect on prostate cancer cells, a promising topic for further research.

A GFP Reporter MR766-Based Flow Cytometry Neutralization Test for Rapid Detection of Zika Virus-Neutralizing Antibodies in Serum Specimens

Zika virus (ZIKV) is an emerging arthropod-borne virus of major public health concern. ZIKV infection is responsible for congenital Zika disease and other neurological defects. Antibody-mediated virus neutralization is an essential component of protective antiviral immunity against ZIKV. In the present study, we assessed whether our GFP reporter ZIKV derived from African viral strain MR766 could be useful for the development of a flow cytometry neutralization test (FNT), as an alternative to the conventional plaque-reduction neutralization test (PRNT). To improve the efficacy of GFP-expressing MR766, we selected virus variant MR766^GFP showing a high level of GFP signal in infected cells. A MR766^GFP-based FNT was assayed with immune sera from adult mice that received ZIKBeHMR-2. The chimeric ZIKV clone ZIKBeHMR-2 comprises the structural protein region of epidemic strain BeH819015 into MR766 backbone. We reported that adult mice inoculated with ZIKBeHMR-2 developed high levels of neutralizing anti-ZIKV antibodies. Comparative analysis between MR766^GFP-based FNT and conventional PRNT was performed using mouse anti-ZIKBeHMR-2 immune sera. Indistinguishable neutralization patterns were observed when compared with PRNT₅₀ and FNT₅₀. We consider that the newly developed MR766^GFP-based FNT is a valid format for measuring ZIKV-neutralizing antibodies in serum specimens.

A Chimeric Zika Virus between Viral Strains MR766 and BeH819015 Highlights a Role for E-glycan Loop in Antibody-mediated Virus Neutralization

Zika virus (ZIKV) is an emerging mosquito-borne flavivirus which is of major public health concern. ZIKV infection is recognized as the cause of congenital Zika disease and other neurological defects, with no specific prophylactic or therapeutic treatments. As the humoral immune response is an essential component of protective immunity, there is an urgent need for effective vaccines that confer protection against ZIKV infection. In the present study, we evaluate the immunogenicity of chimeric viral clone ZIKBeHMR-2, in which the region encoding the structural proteins of the African strain MR766 backbone was replaced with its counterpart from the epidemic strain BeH819015. Three amino-acid substitutions I152T, T156I, and H158Y were introduced in the glycan loop of the E protein (E-GL) making ZIKBeHMR-2 a non-glycosylated virus. Adult BALB/c mice inoculated intraperitoneally with ZIKBeHMR-2 developed anti-ZIKV antibodies directed against viral proteins E and NS1 and a booster dose increased antibody titers. Immunization with ZIKBeHMR-2 resulted in a rapid production of neutralizing anti-ZIKV antibodies. Antibody-mediated ZIKV neutralization was effective against viral strain MR766, whereas epidemic ZIKV strains were poorly sensitive to neutralization by anti-ZIKBeHMR-2 immune sera. From our data, we propose that the three E-GL residues at positions E-152, E-156, and E-158 greatly influence the accessibility of neutralizing antibody epitopes on ZIKV.