(E)-Guggulsterone Inhibits Dengue Virus Replication by Upregulating Antiviral Interferon Responses through the Induction of Heme Oxygenase-1 Expression

Dengue virus (DENV) infection, which causes dengue fever, dengue hemorrhagic fever, and dengue shock syndrome, is a severe global health problem in tropical and subtropical areas. There is no effective vaccine or drug against DENV infection. Thus, the development of anti-DENV agents is imperative. This study aimed to assess the anti-DENV activity of (E)-guggulsterone using a DENV infectious system. A specific inhibitor targeting signal molecules was used to evaluate the molecular mechanisms of action. Western blotting and qRT-PCR were used to determine DENV protein expression and RNA replication, respectively. Finally, an ICR suckling mouse model was used to examine the anti-DENV activity of (E)-guggulsterone in vivo. A dose-dependent inhibitory effect of (E)-guggulsterone on DENV protein synthesis and RNA replication without cytotoxicity was observed. The mechanistic studied revealed that (E)-guggulsterone stimulates Nrf2-mediated heme oxygenase-1 (HO-1) expression, which increases the antiviral interferon responses and downstream antiviral gene expression by blocking DENV NS2B/3B protease activity. Moreover, (E)-guggulsterone protected ICR suckling mice from life-threatening DENV infection. These results suggest that (E)-guggulsterone can be a potential supplement for controlling DENV replication.

Melatonin Inhibits Dengue Virus Infection via the Sirtuin 1-Mediated Interferon Pathway

Dengue virus (DENV) is the causative pathogen in the life-threatening dengue hemorrhagic fever and dengue shock syndrome. DENV is transmitted to humans via the bite of an infected Aedes mosquito. Approximately 100 million people are infected annually worldwide, and most of those live in tropical and subtropical areas. There is still no effective drug or vaccine for treatment of DENV infection. In this study, we set forth to investigate the effect of melatonin, which is a natural hormone with multiple pharmacological functions, against DENV infection. Treatment with subtoxic doses of melatonin dose-dependently inhibited DENV production. Cross-protection across serotypes and various cell types was also observed. Time-of-addition assay suggested that melatonin exerts its influence during the post-entry step of viral infection. The antiviral activity of melatonin partly originates from activation of the sirtuin pathway since co-treatment with melatonin and the sirtuin 1 (SIRT1) inhibitor reversed the effect of melatonin treatment alone. Moreover, melatonin could modulate the transcription of antiviral genes that aid in suppression of DENV production. This antiviral mechanism of melatonin suggests a possible new strategy for treating DENV infection.

A rapid clinic-based service for an emergency department of a tertiary teaching hospital during a dengue outbreak

The 2015 dengue outbreak in southern Taiwan turned into a public health emergency, resulting in a large-scale mobilization of personnel from the emergency department (ED) services operating in and near full capacity to assist with the outbreak. This study aimed to assess a rapid independent clinic-based service (RCS), which was set up and designed to relieve the overcrowding of the regular ambulatory and emergency services during an epidemic of dengue.This is a retrospective cross-sectional study.National Cheng Kung University Hospital, Tainan, Taiwan.Patients with positive test results were enrolled and reviewed to evaluate the efficacy of RCS implementation between August and October 2015. The case-treatment rates stratified by length of stay (LOS) were used to examine the performance of the RCS that was set up outside the ED and designed to relieve the overcrowding of the regular ambulatory and emergency services.Patients with dengue-like illnesses may arrive at the hospital and require optimal ED triage and management thereafter. Although the outbreak resulted in a shortage of spare space in the ED, a proper response from the hospital administration would ameliorate the work overload of the staff and would not decrease the quality of care for critical patients.An early and restrictive intensive intervention was beneficial to health care facilities during a dengue outbreak. Further planning and training of the RCS could be crucial for hospital preparedness for infectious disease outbreaks.

Oligonucleotide-Based Approaches to Inhibit Dengue Virus Replication

Dengue fever is one of the most common viral infections affecting humans. It is an expanding public health problem, particularly in tropical and subtropical regions. No effective vaccine or antiviral therapies against Dengue virus (DENV) infection are available. Therefore, there is a strong need to develop safe and effective therapeutic strategies that can reduce the burden and duration of hospitalizations due to this life-threatening disease. Oligonucleotide-based strategies are considered as an attractive means of inhibiting viral replication since oligonucleotides can be designed to interact with any viral RNA, provided its sequence is known. The resultant targeted destruction of viral RNA interferes with viral replication without inducing any adverse effects on cellular processes. In this review, we elaborate the ribozymes, RNA interference, CRISPR, aptamer and morpholino strategies for the inhibition of DENV replication and discuss the challenges involved in utilizing such approaches.

The amphibian peptide Yodha is virucidal for Zika and dengue viruses

Zika virus (ZIKV) has emerged as a serious health threat in the Americas and the Caribbean. ZIKV is transmitted by the bite of an infected mosquito, sexual contact, and blood transfusion. ZIKV can also be transmitted to the developing fetus in utero, in some cases resulting in spontaneous abortion, fetal brain abnormalities, and microcephaly. In adults, ZIKV infection has been correlated with Guillain-Barre syndrome. Despite the public health threat posed by ZIKV, neither a vaccine nor antiviral drugs for use in humans are currently available. We have identified an amphibian host defense peptide, Yodha, which has potent virucidal activity against ZIKV. It acts directly on the virus and destroys Zika virus particles within 5 min of exposure. The Yodha peptide was effective against the Asian, African, and South American Zika virus strains and has the potential to be developed as an antiviral therapeutic in the fight against Zika virus. The peptide was also effective against all four dengue virus serotypes. Thus, Yodha peptide could potentially be developed as a pan-therapeutic for Zika and dengue viruses.

Potential Medicinal Plants for the Treatment of Dengue Fever and Severe Acute Respiratory Syndrome-Coronavirus

While dengue virus (DENV) infection imposes a serious challenge to the survival of humans worldwide, severe acute respiratory syndrome-coronavirus (SARS-CoV) remains the most devastating pandemic in human history. A significant number of studies have shown that plant-derived substances could serve as potential candidates for the development of safe and efficacious remedies for combating these diseases. Different scientific databases were used to source for literature on plants used against these infections. Thirty-five studies described the traditional use of 25 species from 20 families for treating DENV infection with Carica papaya and Euphorbia hirta were the most widely used across different regions. 13 in vivo studies, 32 in vitro studies, and eight clinical studies were conducted on 30 species from 25 families against different DENV serotypes, while plants from 13 families were reported to inhibit different forms of SARS-CoV, all of which were investigated through in vitro studies. Phytoconstituents belonging to various chemical classes were identified to show a wide range of antiviral activity against these infections. Extensive studies on the potentials of medicinal plants are needed to confirm their efficacy. This paper reveals the capabilities of medicinal plants and their phytochemicals in inhibiting DENV and SARS-CoV infections.

Antiviral Role of Phenolic Compounds against Dengue Virus: A Review

Phenolic compounds have been related to multiple biological activities, and the antiviral effect of these compounds has been demonstrated in several viral models of public health concern. In this review, we show the antiviral role of phenolic compounds against dengue virus (DENV), the most widespread arbovirus globally that, after its re-emergence, has caused multiple epidemic outbreaks, especially in the last two years. Twenty phenolic compounds with anti-DENV activity are discussed, including the multiple mechanisms of action, such as those directed against viral particles or viral proteins, host proteins or pathways related to the productive replication viral cycle and the spread of the infection.

The Antimalarial Compound Atovaquone Inhibits Zika and Dengue Virus Infection by Blocking E Protein-Mediated Membrane Fusion

Flaviviruses bear class II fusion proteins as their envelope (E) proteins. Here, we describe the development of an in vitro quantitative mosquito-cell-based membrane-fusion assay for the E protein using dual split proteins (DSPs). The assay does not involve the use of live viruses and allows the analysis of a membrane-fusion step independent of other events in the viral lifecycle, such as endocytosis. The progress of membrane fusion can be monitored continuously by measuring the activities of Renilla luciferase derived from the reassociation of DSPs during cell fusion. We optimized the assay to screen an FDA-approved drug library for a potential membrane fusion inhibitor using the E protein of Zika virus. Screening results identified atovaquone, which was previously described as an antimalarial agent. Atovaquone potently blocked the in vitro Zika virus infection of mammalian cells with an IC₉₀ of 2.1 µM. Furthermore, four distinct serotypes of dengue virus were also inhibited by atovaquone with IC₉₀ values of 1.6–2.5 µM, which is a range below the average blood concentration of atovaquone after its oral administration in humans. These findings make atovaquone a likely candidate drug to treat illnesses caused by Zika as well as dengue viruses. Additionally, the DSP assay is useful to study the mechanism of membrane fusion in Flaviviruses.

Immortalized stem cell-derived hepatocyte-like cells: An alternative model for studying dengue pathogenesis and therapy

Suitable cell models are essential to advance our understanding of the pathogenesis of liver diseases and the development of therapeutic strategies. Primary human hepatocytes (PHHs), the most ideal hepatic model, are commercially available, but they are expensive and vary from lot-to-lot which confounds their utility. We have recently developed an immortalized hepatocyte-like cell line (imHC) from human mesenchymal stem cells, and tested it for use as a substitute model for hepatotropic infectious diseases. With a special interest in liver pathogenesis of viral infection, herein we determined the suitability of imHC as a host cell target for dengue virus (DENV) and as a model for anti-viral drug testing. We characterized the kinetics of DENV production, cellular responses to DENV infection (apoptosis, cytokine production and lipid droplet metabolism), and examined anti-viral drug effects in imHC cells with comparisons to the commonly used hepatoma cell lines (HepG2 and Huh-7) and PHHs. Our results showed that imHC cells had higher efficiencies in DENV replication and NS1 secretion as compared to HepG2 and Huh-7 cells. The kinetics of DENV infection in imHC cells showed a slower rate of apoptosis than the hepatoma cell lines and a certain similarity of cytokine profiles to PHHs. In imHC, DENV-induced alterations in levels of lipid droplets and triacylglycerols, a major component of lipid droplets, were more apparent than in hepatoma cell lines, suggesting active lipid metabolism in imHC. Significantly, responses to drugs with DENV inhibitory effects were greater in imHC cells than in HepG2 and Huh-7 cells. In conclusion, our findings suggest superior suitability of imHC as a new hepatocyte model for studying mechanisms underlying viral pathogenesis, liver diseases and drug effects.

A model system resembling normal human liver cells is needed for advancement of hepatotropic infectious disease research. Here we show that immortalized cells (imHC) derived from human stem cells have a higher efficiency of DENV replication and a lower rate of cell death in response to DENV infection than the cancer cell-derived model systems currently used. The imHC also have active fat metabolism and respond well to anti-viral drug treatment, making them an attractive model for the initial stage of drug discovery and testing.

Current prevention and potential treatment options for dengue infection

Currently, treatments for dengue infection are only symptomatic as no antiviral agents nor vaccines are available to combat this virus. Despite challenges faced by researchers, many efforts are ongoing to reduce cases of dengue infection either by targeting the vector or the virus. Vector population is monitored and reduced by using mechanical, chemical and biological controls. Chemical control is achieved either by using synthetic or natural insecticides where the latter is more preferable. In biological control, bacteria, fungi and larvivorous fish are utilised to reduce the vector population. Moreover, genes of mosquitoes are also explored to produce progenies which are sterile with low survival ability. Vaccines are among the most effective ways to prevent viral infection. Various approaches have been used and are still being explored towards producing vaccines for dengue. These include live attenuated, inactivated, recombinant subunit, nucleic acid and virus-like particles vaccines. The aim is to produce a vaccine which can target all the four serotypes of the virus. Monoclonal antibodies are widely researched on to equip the host defense mechanism against the dengue virus. Deeper understanding of the virus replication cycle warrants the development of antiviral agents which target viral proteins vital for the replication process. Bioactive compounds are also utilised in the development of antiviral agents. The importance of surveillance and supportive therapy are also discussed.

Validation of a Novel Zebrafish Model of Dengue Virus (DENV-3) Pathology Using the Pentaherbal Medicine Denguenil Vati

Dengue is a devastating viral fever of humans, caused by dengue virus. Using a novel zebrafish model of dengue pathology, we validated the potential anti-dengue therapeutic properties of pentaherbal medicine, Denguenil Vati. At two different time points (at 7 and 14 days post infection with dengue virus), we tested three translational doses (5.8 μg/kg, 28 μg/kg, and 140 μg/kg). Dose- and time-dependent inhibition of the viral copy numbers was identified upon Denguenil Vati treatment. Hepatocyte necrosis, liver inflammation, and red blood cell (RBC) infiltration into the liver were significantly inhibited upon Denguenil treatment. Treatment with Denguenil Vati significantly recovered the virus-induced decreases in total platelet numbers and total RBC count, and concomitantly increasing hematocrit percentage, in a dose- and time-dependent manner. Conversely, virus-induced white blood cell (WBC) counts were significantly normalized. Virus-induced hemorrhage was completely abrogated by Denguenil after 14 days, at all the doses tested. Gene expression analysis identified a significant decrease in disease-induced endothelial apoptotic marker Angiopoetin2 (Ang-2) and pro-inflammatory chemokine marker CCL3 upon Denguenil treatment. Presence of gallic acid, ellagic acid, palmetin, and berberine molecules in the Denguenil formulation was detected by HPLC. Taken together, our results exhibit the potential therapeutic properties of Denguenil Vati in ameliorating pathological features of dengue.

DenvInD: dengue virus inhibitors database for clinical and molecular research

Dengue virus (DENV) researchers often face challenges with the highly time-consuming process of collecting and curating information on known inhibitors during the standard drug discovery process. To this end, however, required collective information is not yet available on a single platform. Hence, we have developed the DenvInD database for experimentally validated DENV inhibitors against its known targets presently hosted at https://webs.iiitd.edu.in/raghava/denvind/. This database provides comprehensive information, i.e. PubChem IDs, SMILES, IC50, EC50, CC50, and wherever available Ki values of the 484 compounds in vitro validated as inhibitors against respective drug targets of DENV. Also, the DenvInD database has been linked to the user-friendly web-based interface and accessibility features, such as simple search, advanced search and data browsing. All the required data curation was conducted manually from the reported scientific literature and PubChem. The collected information was then organized into the DenvInD database using sequence query language under user interface by hypertext markup language. DenvInD is the first useful repository of its kind which would augment the DENV drug discovery research by providing essential information on known DENV inhibitors for molecular docking, computational screening, pharmacophore modeling and quantitative structure-activity relationship modeling.

Multi-sulfonated ligands on gold nanoparticles as virucidal antiviral for Dengue virus

Dengue virus (DENV) causes 390 million infections per year. Infections can be asymptomatic or range from mild fever to severe haemorrhagic fever and shock syndrome. Currently, no effective antivirals or safe universal vaccine is available. In the present work we tested different gold nanoparticles (AuNP) coated with ligands ω-terminated with sugars bearing multiple sulfonate groups. We aimed to identify compounds with antiviral properties due to irreversible (virucidal) rather than reversible (virustatic) inhibition. The ligands varied in length, in number of sulfonated groups as well as their spatial orientation induced by the sugar head groups. We identified two candidates, a glucose- and a lactose-based ligand showing a low EC50 (effective concentration that inhibit 50% of the viral activity) for DENV-2 inhibition, moderate toxicity and a virucidal effect in hepatocytes with titre reduction of Median Tissue Culture Infectious Dose log10TCID50 2.5 and 3.1. Molecular docking simulations complemented the experimental findings suggesting a molecular rationale behind the binding between sulfonated head groups and DENV-2 envelope protein.

Structure-Based Design of Antivirals against Envelope Glycoprotein of Dengue Virus

Dengue virus (DENV) presents a significant threat to global public health with more than 500,000 hospitalizations and 25,000 deaths annually. Currently, there is no clinically approved antiviral drug to treat DENV infection. The envelope (E) glycoprotein of DENV is a promising target for drug discovery as the E protein is important for viral attachment and fusion. Understanding the structure and function of DENV E protein has led to the exploration of structure-based drug discovery of antiviral compounds and peptides against DENV infections. This review summarizes the structural information of the DENV E protein with regards to DENV attachment and fusion. The information enables the development of antiviral agents through structure-based approaches. In addition, this review compares the potency of antivirals targeting the E protein with the antivirals targeting DENV multifunctional enzymes, repurposed drugs and clinically approved antiviral drugs. None of the current DENV antiviral candidates possess potency similar to the approved antiviral drugs which indicates that more efforts and resources must be invested before an effective DENV drug materializes.

Reassessing therapeutic antibodies for neglected and tropical diseases

In the past two decades there has been a significant expansion in the number of new therapeutic monoclonal antibodies (mAbs) that are approved by regulators. The discovery of these new medicines has been driven primarily by new approaches in inflammatory diseases and oncology, especially in immuno-oncology. Other recent successes have included new antibodies for use in viral diseases, including HIV. The perception of very high costs associated with mAbs has led to the assumption that they play no role in prophylaxis for diseases of poverty. However, improvements in antibody-expression yields and manufacturing processes indicate this is a cost-effective option for providing protection from many types of infection that should be revisited. Recent technology developments also indicate that several months of protection could be achieved with a single dose. Moreover, new methods in B cell sorting now enable the systematic identification of high-quality antibodies from humanized mice, or patients. This Review discusses the potential for passive immunization against schistosomiasis, fungal infections, dengue, and other neglected diseases.

When and what to test for: A cost-effectiveness analysis of febrile illness test-and-treat strategies in the era of responsible antibiotic use

BACKGROUND

Febrile illness caused by viral and bacterial diseases (e.g., dengue and leptospirosis) often have similar symptoms and are difficult to differentiate without diagnostic tests. If not treated appropriately, patients may experience serious complications. The question of what diagnostic tests to make available to providers in order to inform antibiotic therapy remains an open problem for health services facing limited resources.

METHODS AND FINDINGS

We formulated the problem of minimizing the weighted average of antibiotic underuse and overuse to inform the optimal diagnostic test and antibiotic treatment options for given occurrence probabilities of several bacterial and viral infections. We modeled the weight of antibiotic overuse as a monetary penalty per unnecessarily administered course, which we varied in both the base case and sensitivity analysis. Detailed Markov cohort models of febrile illness progression were used to estimate the weight of antibiotic underuse. The model accounted for multiple infections simultaneously and incorporated test, treatment, and other direct and indirect costs, as well as the effect of delays in seeking care and test turnaround times. We used the Markov models to numerically estimate disability-adjusted life years (DALYs), pre-penalty costs, and likelihood of antibiotics overuse per patient for fifteen different strategies in two example settings in Thailand, one with a higher probability of bacterial infections (Northern Thailand, Scenario A) and one with a higher probability of viral infections (Bangkok, Scenario B). We found that empirical antibiotic treatment to all patients always incurs the lowest pre-penalty cost (Scenario A: $47.5/patient, $100.6/patient, $149.5/patient for patients seeking care on day one, day four, and day ten respectively; Scenario B: $94.1/patient, $108.7/patient, $122.1/patient on day one, day four, and day ten respectively), and the lowest DALYs, (Scenario A: 0.2 DALYs/patient, 0.9 DALYs/patient, 1.7 DALYs/patient on day one, day four, and day ten, respectively; Scenario B: 0.5 DALYs/patient, 0.7 DALYs/patient, 0.9 DALYs/patient on day one, day four, and day ten, respectively). However, such strategy resulted in the highest proportion of antibiotic overuse per patient (Scenario A: 38.1%, 19.3%, 7.5% on day one, day four, and day ten, respectively; Scenario B: 82.9%, 42.1%, 16.3% on day one, day four, and day ten, respectively). Consequently, empirical antibiotic treatment became suboptimal with antibiotic overuse penalties above $12,800/course, $18,400/course, $23,900/course for patients presenting on day one, day four, and day ten in Scenario A and above $1,100/course, $1,500/course, $1,600/course for patients presenting on day one, day four, and day ten in Scenario B.

CONCLUSIONS

Empirical antibiotic treatment to all patients provided the best outcomes if antibiotic overuse was not the primary concern or if presenting with viral disease (such as dengue) was unlikely. Empirical antibiotic treatment to severe patients only was in most cases not beneficial. Otherwise, strategies involving diagnostic tests became optimal. In particular, our results indicated that single test strategies (bacterial RDT or viral PCR) were optimal in regions with a greater probability of presenting with viral infection. PCR-led strategies (e.g., parallel bacterial PCR, or multiplex PCR) are robust under parameter uncertainty (e.g., with uncertain disease occurrence probabilities).

Discovery of Dengue Virus Inhibitors

To date, there is still no approved anti-dengue agent to treat dengue infection in the market. Although the only licensed dengue vaccine, Dengvaxia is available, its protective efficacy against serotypes 1 and 2 of dengue virus was reported to be lower than serotypes 3 and 4. Moreover, according to WHO, the risk of being hospitalized and having severe dengue increased in seronegative individuals after they received Dengvaxia vaccination. Nevertheless, various studies had been carried out in search of dengue virus inhibitors. These studies focused on the structural (C, prM, E) and non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5) of dengue virus as well as host factors as drug targets. Hence, this article provides an overall up-to-date review of the discovery of dengue virus inhibitors that are only targeting the structural and non-structural viral proteins as drug targets.

Exploration of Carica papaya bioactive compounds as potential inhibitors of dengue NS2B, NS3 and NS5 protease

Current outbreak of dengue has shown serious health concerns in Pakistan. The present study reports the anti-dengue potential of Carica papaya natural compounds. The leaves of C. papaya have previously shown promising results in cure of Dengue fever. The aim of this project is to find specific bioactive compounds by computational screening and biological activities of C. papaya against serine NS2B, NS3 and NS5 proteases of dengue virus. Docking study resulted in the screening of nine bioactive compounds having highest docking scores. However, three compounds namely epigallocatchin, catechin and protocatechuric acid had the strongest binding affinity with the active residues i.e., Ser135, His51 and Asp75 of dengue virus serine proteases. Results also indicated that the extract of C. papaya was a strong antimicrobial and antioxidant agent. It is concluded that the C. papaya compounds can be commercially applied for medical formulations against dengue virus.

Anti-inflammatory effect of mushrooms in dengue-infected human monocytes

Pathogenesis of dengue fever has been associated with the activation of the cytokine cascade that triggered inflammatory responses. The inflammatory reactions in dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS) are the main cause of haemorrhagic manifestations, coagulation disorders, vascular permeability, hypotension and shock which could exacerbate the condition of the disease. In an earlier study, extracts belonging to Lignosus rhinocerotis, Pleurotus giganteus, Hericium erinaceus, Schizophyllum commune and Ganoderma lucidium mushrooms were screened for antidengue virus activities. We found that hot aqueous extract (HAE) and aqueous soluble separated from ethanol extract (ASE) exhibited their potential to reduce dengue viral load which were observed in plaque reduction assay and real-time RT-PCR. In continuation of our previous findings, this study was initiated to further investigate the other aspect; the anti-inflammatory activities of HAE and ASE of L. rhinocerotis, P. giganteus, H. erinaceus, S. commune and G. lucidium on human monocytes infected with dengue virus-2 (DENV-2) New guinea C strain. Human monocytes infected with DENV-2 were treated with mushroom extracts for 48 hours. The cytokine profile coincides with dengue infection, i.e. IFN-γ, TNF-α, IL-1β, IL-6, IL-8, and IL-10 were measured by BD OptEIATM Elisa Kit. The expression of these cytokines was significantly elevated in untreated infected cells two days after infection. However, after treated with mushroom extracts prominent anti-inflammatory effect were detected towards IFN-γ, IL-10, TNF-α, IL-6, and IL-1β. The most significant anti-inflammatory effects were detected in HAE of G. lucidium, S. commune, P. giganteus and ASE of L. rhinocerotis and the effects were comparable with dexamethasone, the reference inhibitor. These results demonstrated that mushroom HAE or ASE could successfully have suppressed cytokine production in dengue-infected monocytes and has a great potential to develop an antiinflammatory agent from mushroom extract for the treatment of dengue infection.

Dengue Virus Type 1 Infection in Traveler Returning from Tanzania to Japan, 2019

The largest outbreak of dengue fever in Tanzania is ongoing. Dengue virus type 1 was diagnosed in a traveler who returned from Tanzania to Japan. In phylogenetic analysis, the detected strain was close to the Singapore 2015 strain, providing a valuable clue for investigating the dengue outbreak in Tanzania.

RIG-I Activation by a Designer Short RNA Ligand Protects Human Immune Cells against Dengue Virus Infection without Causing Cytotoxicity

Virus-derived double-stranded RNA (dsRNA) molecules containing a triphosphate group at the 5' end are natural ligands of retinoic acid-inducible gene I (RIG-I). The cellular pathways and proteins induced by RIG-I are an essential part of the innate immune response against viral infections. Starting from a previously published RNA scaffold (3p10L), we characterized an optimized small dsRNA hairpin (called 3p10LG9, 25 nucleotides [nt] in length) as a highly efficient RIG-I activator. Dengue virus (DENV) infection in cell lines and primary human skin cells could be prevented and restricted through 3p10LG9-mediated activation of RIG-I. This antiviral effect was RIG-I and interferon signal dependent. The effect was temporary and was reversed above a saturating concentration of RIG-I ligand. This finding revealed an effective feedback loop that controls potentially damaging inflammatory effects of the RIG-I response, at least in immune cells. Our results show that the small RIG-I activator 3p10LG9 can confer short-term protection against DENV and can be further explored as an antiviral treatment in humans.IMPORTANCE Short hairpin RNA ligands that activate RIG-I induce antiviral responses in infected cells and prevent or control viral infections. Here, we characterized a new short hairpin RNA molecule with high efficacy in antiviral gene activation and showed that this molecule is able to control dengue virus infection. We demonstrate how structural modifications of minimal RNA ligands can lead to increased potency and a wider window of RIG-I-activating concentrations before regulatory mechanisms kick in at high concentrations. We also show that minimal RNA ligands induce an effective antiviral response in human skin dendritic cells and macrophages, which are the target cells of initial infection after the mosquito releases virus into the skin. Using short hairpin RNA as RIG-I ligands could therefore be explored as antiviral therapy.

Erupt of malaria, dengue and chikungunya in Pakistan: Recent insights about prevalence, diagnosis and treatment

Malaria, dengue and chikungunya are the most rampant mosquito-borne infections predominantly in Pakistan. They pose a serious threat and cause a havoc for the victims owing to the life threatening signs and symptoms marked with elevated morbidity and mortality rate. It seems hard to discriminate due to common indications, consequently, deserves appropriate diagnosis prior elevated toll of death. Present article encompasses depth insights about their prevalence, diagnosis and clinical manifestation if erupt in the pandemic. However, host-vector-host cycle is the root cause of transmission and diverse mosquito species confer dissimilar infections. Indeed these infections are seasonal but other factors like flood, open irrigation channels, immense agricultural land, rich fauna and water reservoirs can't be overlooked. Dire need was felt to acknowledge and aware the public about local transmission, vector control, entomologic, research resources, diagnosis and advancement in healthcare system to alleviate them absolutely in future.

Nucleoside Analogs with Selective Antiviral Activity against Dengue Fever and Japanese Encephalitis Viruses

Dengue virus (DENV) and Japanese encephalitis virus (JEV) are important arthropod-borne viruses from the Flaviviridae family. DENV is a global public health problem with significant social and economic impacts, especially in tropical and subtropical areas. JEV is a neurotropic arbovirus endemic to east and southeast Asia. There are no U.S. FDA-approved antiviral drugs available to treat or to prevent DENV and JEV infections, leaving nearly one-third of the world's population at risk for infection. Therefore, it is crucial to discover potent antiviral agents against these viruses. Nucleoside analogs, as a class, are widely used for the treatment of viral infections. In this study, we discovered nucleoside analogs that possess potent and selective anti-JEV and anti-DENV activities across all serotypes in cell-based assay systems. Both viruses were susceptible to sugar-substituted 2'-C-methyl analogs with either cytosine or 7-deaza-7-fluoro-adenine nucleobases. Mouse studies confirmed the anti-DENV activity of these nucleoside analogs. Molecular models were assembled for DENV serotype 2 (DENV-2) and JEV RNA-dependent RNA polymerase replication complexes bound to nucleotide inhibitors. These models show similarities between JEV and DENV-2, which recognize the same nucleotide inhibitors. Collectively, our findings provide promising compounds and a structural rationale for the development of direct-acting antiviral agents with dual activity against JEV and DENV infections.

Insect anionic septapeptides suppress DENV replication by activating antiviral cytokines and miRNAs in primary human monocytes

Dengue viruses (DENVs) have threatened 2/3 of the world population for decades. Thus, combating DENV infection with either antiviral therapy or protective vaccination is an urgent goal. In the present study, we investigated the anti-DENV activity of insect cell-derived anionic septapeptides from C6/36 mosquito cell cultures persistently infected with DENV. These molecules were previously shown to protect C6/36 and Vero cells against DENV infection. We found that treatment with these septapeptides strongly and rapidly downregulated the multiplication of DENV-1 16007, DENV-3 16562, and DENV-4 1036 but not that of DENV-2 16681 in primary human monocytes. This inhibitory effect was likely mediated through various routes including the increased production of antiviral cytokines (IFN-I), activation of mononuclear cell migration, and upregulation of the expression of antiviral miRNAs (has-miR-30e*, has-miR-133a, and has-miR-223) and inflammation-related miRNAs (has-miR-146a and has-miR-147). In conclusion, anionic septapeptides exerted anti-DENV activity in human monocytes through the upregulation of innate immune responses and the activation of several previously reported antiviral and inflammation-related miRNAs.

Drug repurposing of N-acetyl cysteine as antiviral against dengue virus infection

Liver injury is one of the hallmark features of severe dengue virus (DENV) infection since DENV can replicate in the liver and induce hepatocytes to undergo apoptosis. N-acetyl cysteine (NAC), which is a clinically-used drug for treating acetaminophen toxicity, was found to benefit patients with DENV-induced liver injury; however, its mechanism of action remains unclear. Accordingly, our aim was to repurpose NAC in the preclinical studies to investigate its mechanism of action. Time of addition experiments in HepG2 cells elucidated effectiveness of NAC to reduce infectious virion at pre-, during- and post infection. In DENV-infected mice, NAC improved DENV-associated clinical manifestations, including leucopenia and thrombocytopenia, and reduced liver injury and hepatocyte apoptosis. Interestingly, we discovered that NAC significantly reduced DENV production in HepG2 cells and in liver of DENV-infected mice by induction of antiviral responses via interferon signaling. NAC treatment in DENV-infected mice helped to maintain antioxidant enzymes and redox balance in the liver. Therefore, NAC reduces DENV production and oxidative damage to ameliorate DENV-induced liver injury. Taken together, these findings suggest the novel therapeutic potential of NAC in DENV-induced liver injury and recommend evaluating its efficacy and safety in humans with DENV-induced liver injury.