[Clinical Update on Diagnosis, Treatment and Prevention of Dengue]

Dengue is a vector-borne disease that has a significant impact on global public health. The vector mosquito belongs to the genus Aedes. Two species play a key role in human transmission: Ae. aegypti, which has adapted to the urban environment of highly populated areas in tropical and subtropical countries, leading to a dramatic increase in dengue cases over the years, and Ae. albopictus, which poses a potential threat to temperate climate countries due to its ability to adapt to colder climates. The disease is widespread across the world, posing a risk to nearly half of the world's population. Although most cases are asymptomatic, dengue causes a burden on healthcare systems and mainly affects the younger population. The disease is also spreading to temperate climate countries, thus becoming a global threat. Vector control measures and vaccine development have been the main prevention strategies, as there is still no effective treatment for the disease.

Association of different blood groups in patients with Dengue fever and their relationship with the severity of the illness

Objective

To determine the association of different blood groups in patients with Dengue fever and their relationship with the severity of the illness.

Methods

A hospital-based descriptive study was conducted in the Dengue Isolation Ward of Lady Reading Hospital Peshawar from March 2020 to September 2020. Patients with Dengue fever were included in the study. The severity of the illness was categorized as "Dengue fever (DF)", "Dengue hemorrhagic fever (DHF)", and "Dengue shock syndrome (DSS)". The patients' blood groups were determined as A, B, AB, and O groups. All the data were recorded and analyzed using SPSS® version 23. Chi-square (χ2) and student t-test were applied, and a p-value of ≤0.05 was considered significant.

Results

Out of 160 patients, 119(74.4%) were males; the patient's mean age was 38.09±15.68 SD, IQR=25 years. Greater proportion (28%) of the young men (up to 40 years) was affected compared to 9% young women. Fever (99%) and body aches (96%) were the most common presentation of DF, complicated by bleeding in 30.6% and shock in 9.4% of the patients. The majority (63.1%) of the patients had DF; 27.5% had DHF, and 9.4% had DSS. Sixty three (39.4%) patients had blood Group-B and 5.6% had Group-AB (p=0.97). The proportion of patients with different blood groups and the type/severity of the DF were almost identical except the fact that none of the patient with group AB had DSS. There was significant gender difference of hemoglobin (p=0.008, 95%CI=0.439, 2.844), hematocrit (p=0.012, 95%CI=0.00974, 0.07946); and Alanine Aminotransferase levels (p=0.002, 95%CI=-332.032, -72.233).

Conclusion

Patients with blood Group-B were more frequent and AB was least commonly affected by the Dengue-virus infections. However, no association was found between a particular blood group and disease severity. Greater proportions of the younger men had Dengue infections.

Integration of population-level data sources into an individual-level clinical prediction model for dengue virus test positivity

The differentiation of dengue virus (DENV) infection, a major cause of acute febrile illness in tropical regions, from other etiologies, may help prioritize laboratory testing and limit the inappropriate use of antibiotics. While traditional clinical prediction models focus on individual patient-level parameters, we hypothesize that for infectious diseases, population-level data sources may improve predictive ability. To create a clinical prediction model that integrates patient-extrinsic data for identifying DENV among febrile patients presenting to a hospital in Thailand, we fit random forest classifiers combining clinical data with climate and population-level epidemiologic data. In cross validation, compared to a parsimonious model with the top clinical predictors, a model with the addition of climate data, reconstructed susceptibility estimates, force of infection estimates, and a recent case clustering metric, significantly improved model performance.

The 1H, 15N and 13C resonance assignments of dengue virus capsid protein with the deletion of the intrinsically disordered N-terminal region

Dengue virus belongs to the Flaviviridae family, being responsible for an endemic arboviral disease in humans. It is an enveloped virus, whose genome is a positive-stranded RNA packaged by the capsid protein. Dengue virus capsid protein (DENVC) forms homodimers in solution organized in 4 α-helices and an intrinsically disordered N-terminal region. The N-terminal region is involved in the binding of membranous structures in host cells and in the recognition of nucleotides. Here we report the ¹H, ¹⁵N and ¹³C resonance assignments of the DENVC with the deletion of the first 19 intrinsically disordered residues. The backbone chemical shift perturbations suggest changes in the α1 and α2 helices between full length and the truncated proteins.

A human iPSC-array-based GWAS identifies a virus susceptibility locus in the NDUFA4 gene and functional variants

Population-based studies to identify disease-associated risk alleles typically require samples from a large number of individuals. Here, we report a human-induced pluripotent stem cell (hiPSC)-based screening strategy to link human genetics with viral infectivity. A genome-wide association study (GWAS) identified a cluster of single-nucleotide polymorphisms (SNPs) in a cis-regulatory region of the NDUFA4 gene, which was associated with susceptibility to Zika virus (ZIKV) infection. Loss of NDUFA4 led to decreased sensitivity to ZIKV, dengue virus, and SARS-CoV-2 infection. Isogenic hiPSC lines carrying non-risk alleles of SNPs or deletion of the cis-regulatory region lower sensitivity to viral infection. Mechanistic studies indicated that loss/reduction of NDUFA4 causes mitochondrial stress, which leads to the leakage of mtDNA and thereby upregulation of type I interferon signaling. This study provides proof-of-principle for the application of iPSC arrays in GWAS and identifies NDUFA4 as a previously unknown susceptibility locus for viral infection.

Clinical and Molecular facets of Dengue Virus infection from Bengaluru, South India

Background

Dengue virus (DENV) continues to be an epidemic with high mortality rates. The clinical features, especially in the early phase of infection, are nonspecific and there is no single marker that can be reliably deployed for diagnostics. Further, serotype and genotype diversity is not clearly understood. This study was conceived to understand the performance characteristics of various diagnostic markers; serotype and genotype distribution is thus a vital requirement.

Methods

A subset of blood samples was obtained for all the clinically suspected Dengue cases during the period January to December 2017. The samples were tested for IgM and IgG antibodies and NS1 antigen by both ELISA and rapid tests. Real-time PCR, Conventional PCR and sequencing was performed based on the serology results. Correlation of the data with demographic and clinical details was used to analyze the performance characteristics of various tests.

Results

Clinical signs and symptoms could not predict dengue positivity due to lack of specific symptoms. The performance of IgM rapid test was found to be lower than the ELISA method (53.5% agreement). The NS1 rapid and NS1 ELISA tests were comparable (89.2% agreement). Majority of the infections were caused due to DEN-2 serotype and phylogenetic analysis revealed all the sequenced DEN-2 serotypes belong to Genotype IV. Three sequences were deposited into NCBI GenBank (GenBank accession number MW583116, MW579054 and MW579053).

Conclusion

Our comprehensive data suggests that NS1 ELISA and PCR are best used in the early phase of dengue infection (< 5 days post-onset of fever), whereas IgM antibody detection is reliable only in the late phase. We also highlight the unreliable performance of rapid tests.

Diagnosis of Dengue in a returning traveler from Pakistan suspected of COVID-19, California, USA

Dengue and COVID-19 cocirculation presents a diagnostic conundrum for physicians evaluating patients with acute febrile illnesses, both in endemic regions and among returning travelers. We present a case of a returning traveler from Pakistan who, following repeated negative SARS-CoV-2 tests, was found to have a Dengue virus serotype 2 infection.

Cytokine IP-10 and GM-CSF are prognostic biomarkers for severity in secondary dengue infection

Dengue virus (DENV) infection is mostly prevalent in tropical and sub-tropical regions of the world. Though most DENV infections are self-limiting febrile like-illness, a small proportion of secondary infection is fatal, if untreated symptomatically. Among various factors involved in severe dengue, immune enhancement by cytokine is the major one. The objective of the study is to elucidate serum cytokine expression among primary and secondary infection and determine if any signature cytokine is correlated with disease severity. Seventy-six serum samples at acute time points were collected during the 2017 DENV outbreak in Madurai, Tamil Nadu. Among the 76 serum samples, 49 belong to primary and 27 to secondary DENV infection. Interestingly, a large number of primary infection presented with DHF/DSS symptoms and, children were found prone to DHF and DSS in secondary infection. The serum samples were analysed for inflammatory cytokines, namely IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-17A, IFN-γ, TNF-α, IP-10 and GM-CSF using ELISA assay as well as mRNA analysis using qPCR. Among the 12 inflammatory cytokines analysed IP-10 and GMCSF mRNA and protein shows significant upregulation in secondary infection. Similarly, a strong correlation was observed between GM-CSF and IP-10 with thrombocytopenia, ascites, serous effusion and spontaneous bleeding. Based on the observations, GM-CSF and IP-10 could be a potential prognostic biomarkers for secondary DENV infection.

A proposed molecular mechanism for pathogenesis of severe RNA-viral pulmonary infections

Background: Certain riboviruses can cause severe pulmonary complications leading to death in some infected patients. We propose that DNA damage induced-apoptosis accelerates viral release, triggered by depletion of host RNA binding proteins (RBPs) from nuclear RNA bound to replicating viral sequences. Methods: Information theory-based analysis of interactions between RBPs and individual sequences in the Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2), Influenza A (H3N1), HIV-1, and Dengue genomes identifies strong RBP binding sites in these viral genomes. Replication and expression of viral sequences is expected to increasingly sequester RBPs - SRSF1 and RNPS1. Ordinarily, RBPs bound to nascent host transcripts prevents their annealing to complementary DNA. Their depletion induces destabilizing R-loops. Chromosomal breakage occurs when an excess of unresolved R-loops collide with incoming replication forks, overwhelming the DNA repair machinery. We estimated stoichiometry of inhibition of RBPs in host nuclear RNA by counting competing binding sites in replicating viral genomes and host RNA. Results: Host RBP binding sites are frequent and conserved among different strains of RNA viral genomes. Similar binding motifs of SRSF1 and RNPS1 explain why DNA damage resulting from SRSF1 depletion is complemented by expression of RNPS1. Clustering of strong RBP binding sites coincides with the distribution of RNA-DNA hybridization sites across the genome. SARS-CoV-2 replication is estimated to require 32.5-41.8 hours to effectively compete for binding of an equal proportion of SRSF1 binding sites in host encoded nuclear RNAs. Significant changes in expression of transcripts encoding DNA repair and apoptotic proteins were found in an analysis of influenza A and Dengue-infected cells in some individuals. Conclusions: R-loop-induced apoptosis indirectly resulting from viral replication could release significant quantities of membrane-associated virions into neighboring alveoli. These could infect adjacent pneumocytes and other tissues, rapidly compromising lung function, causing multiorgan system failure and other described symptoms.

A proposed molecular mechanism for pathogenesis of severe RNA-viral pulmonary infections

Background: Certain riboviruses can cause severe pulmonary complications leading to death in some infected patients. We propose that DNA damage induced-apoptosis accelerates viral release, triggered by depletion of host RNA binding proteins (RBPs) from nuclear RNA bound to replicating viral sequences. Methods: Information theory-based analysis of interactions between RBPs and individual sequences in the Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2), Influenza A (H3N2), HIV-1, and Dengue genomes identifies strong RBP binding sites in these viral genomes. Replication and expression of viral sequences is expected to increasingly sequester RBPs - SRSF1 and RNPS1. Ordinarily, RBPs bound to nascent host transcripts prevents their annealing to complementary DNA. Their depletion induces destabilizing R-loops. Chromosomal breakage occurs when an excess of unresolved R-loops collide with incoming replication forks, overwhelming the DNA repair machinery. We estimated stoichiometry of inhibition of RBPs in host nuclear RNA by counting competing binding sites in replicating viral genomes and host RNA. Results: Host RBP binding sites are frequent and conserved among different strains of RNA viral genomes. Similar binding motifs of SRSF1 and RNPS1 explain why DNA damage resulting from SRSF1 depletion is complemented by expression of RNPS1. Clustering of strong RBP binding sites coincides with the distribution of RNA-DNA hybridization sites across the genome. SARS-CoV-2 replication is estimated to require 32.5-41.8 hours to effectively compete for binding of an equal proportion of SRSF1 binding sites in host encoded nuclear RNAs. Significant changes in expression of transcripts encoding DNA repair and apoptotic proteins were found in an analysis of influenza A and Dengue-infected cells in some individuals. Conclusions: R-loop-induced apoptosis indirectly resulting from viral replication could release significant quantities of membrane-associated virions into neighboring alveoli. These could infect adjacent pneumocytes and other tissues, rapidly compromising lung function, causing multiorgan system failure and other described symptoms.

Generative Adversarial Networks (GANs) Based Synthetic Sampling for Predictive Modeling

In the present report we evaluate the possible utility of the Generative Adversarial Networks (GANs) in mapping the chemical structural space for molecular property profiles, with the goal of subsequently yielding synthetic (artificial) samples for ligand-based molecular modeling. Two case studies are considered: BACE-1 (β-Secretase 1) and DENV (Dengue Virus) inhibitory activities, with the former focused on data populating and the latter on data balancing tasks. We train GANs using subsamples extracted from datasets for each bioactivity endpoint, and apply the trained networks in generating synthetic examples from the respective bioactivity chemical spaces. Original and synthetic samples are pooled together and employed to build BACE-1 and DENV inhibitory activity classifiers and their performance evaluated over tenfold external validation sets. In both case studies, the obtained classifiers demonstrate satisfactory predictivity with the former yielding accuracy (ACC) and Mathew's correlation coefficient (MCC) values of 0.80 and 0.59, while the latter produces balanced accuracy(BACC) and MCC values of 0.81 and 0.70, respectively. Moreover, the statistics of these classifiers are compared with those of other models in the literature demonstrating comparable to better performance. These results suggest that GANs may be useful in mapping the chemical space for molecular property profiles of interest, and thus allow for the extraction of synthetic examples for computational modeling.

Potent antiviral activity of novel multi-substituted 4-anilinoquin(az)olines

Screening a series of 4-anilinoquinolines and 4-anilinoquinazolines enabled identification of potent novel inhibitors of dengue virus (DENV). Preparation of focused 4-anilinoquinoline/quinazoline scaffold arrays led to the identification of a series of high potency 6-substituted bromine and iodine derivatives. The most potent compound 6-iodo-4-((3,4,5-trimethoxyphenyl)amino)quinoline-3-carbonitrile (47) inhibited DENV infection with an EC₅₀ = 79 nM. Crucially, these compounds showed very limited toxicity with CC₅₀ values >10 µM in almost all cases. This new promising series provides an anchor point for further development to optimize compound properties.

Nature of Complex Network of Dengue Epidemic as a Scale-Free Network

Objectives

Dengue epidemic is a dynamic and complex phenomenon that has gained considerable attention due to its injurious effects. The focus of this study is to statically analyze the nature of the dengue epidemic network in terms of whether it follows the features of a scale-free network or a random network.

Methods

A multifarious network of Aedes aegypti is addressed keeping the viewpoint of a complex system and modelled as a network. The dengue network has been transformed into a one-mode network from a two-mode network by utilizing projection methods. Furthermore, three network features have been analyzed, the power-law, clustering coefficient, and network visualization. In addition, five methods have been applied to calculate the global clustering coefficient.

Results

It has been observed that dengue epidemic follows a power-law, with the value of its exponent γ = −2.1. The value of the clustering coefficient is high for dengue cases, as weight of links. The minimum method showed the highest value among the methods used to calculate the coefficient. Network visualization showed the main areas. Moreover, the dengue situation did not remain the same throughout the observed period.

Conclusions

The results showed that the network topology exhibits the features of a scale-free network instead of a random network. Focal hubs are highlighted and the critical period is found. Outcomes are important for the researchers, health officials, and policy makers who deal with arbovirus epidemic diseases. Zika virus and Chikungunya virus can also be modelled and analyzed in this manner.

Characterization of dengue virus in Aedes aegypti and Aedes albopictus spp. of mosquitoes: A study in Khyber Pakhtunkhwa, Pakistan

Dengue is a vector-borne disease caused by dengue virus. According to the recent report of CDC that one-third population of the world are at high risk with Dengue fever. The prevalence of the dengue hemorrhagic fever was found more in tropical and sub-tropical regions of the world. Aedes mosquitoes was reported as the main cause of transmission of dengue virus. So the current study was planned to characterize the virus in Aedes mosquitoes collected from different area of Pakistan. In current investigation, Aedes mosquitoes and larvae were trapped under conducive conditions which are counted as 495 Aedes mosquitoes and 260 Aedes larvae. First of all, adult mosquitoes were identified morphologically under microscopy, counted as 73.3% Ae. aegypti and 26.7% Ae. albopictus. Finally, reverse transcriptase polymerase chain reaction analyses that only 4 adults of Aedes mosquitoes and 10 Aedes larvae as naturally infected with dengue virus with possible source Ae. aegypti. This study basically uncovered the presence of virus in different species of mosquitoes in southern regions of Pakistan. The present study will also give us an insight for vector control programs of dengue virus in the affected area.

Organelle dynamics and viral infections: at cross roads

Viruses are obligate intracellular parasites of the host cells. A commonly accepted view is the requirement of internal membranous structures for various aspects of viral life cycle. Organelles enable favourable intracellular environment for several viruses. However, studies reporting organelle dynamics upon viral infections are scant. In this review, we aim to summarize and highlight modulations caused to various organelles upon viral infection or expression of its proteins.

Seroprevalence of Dengue Virus, West Nile Virus, Chikungunya Virus, and Zika Virus in International Travelers Attending a Travel and Migration Center in 2015-2017, Southern Italy

International travelers to areas endemic for vector-borne diseases (VBDs) may be at risk of contracting and spreading these diseases. The aim of this study was to evaluate the prevalence of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies that are specific for Dengue Virus (DV), West Nile Virus (WNV), Chikungunya Virus (CHIKV), or Zika Virus (ZV) in a cohort of international travelers. The study enrolled travelers who attended the Travel Medicine and Migration outpatient service of Local Health Unit of Bari, Italy, in March 2015-June 2017 for counseling and vaccine prophylaxis before travel. After receiving informed consent, post-travel blood samples were tested for IgM and IgG antibodies specific for DV, WNV, CHIKV, and ZV. Of the 207 travelers attending the vaccine service, 156 (75%) were enrolled. Of the 156 subjects, 23 (14.7%) had IgM and/or IgG antibodies specific for at least one VBD. Of these, 12 (52%) were asymptomatic. Nineteen (12.2% of the whole cohort), nine (5.8%), nine (5.8%), and two (1.3%) subjects had IgM and/or IgG antibodies specific for DV, WNV, CHIKV, and ZV, respectively. Ten subjects (6.4%) harbored antibodies that were specific for more than one VBD. A significant number of the international travelers were DV-positive. Our findings suggest that international travelers should undergo serological surveillance, particularly those who travel frequently and for long periods to areas that are endemic for hemorrhagic dengue. Due to a possible risk of introducing VBDs into nonendemic areas, increased awareness among physicians and travelers and appropriate laboratory detection are crucial. There are currently no licensed vaccines for these VBDs in Italy or other European countries; the main preventive measures are protection from mosquito bites and vector control.

The antimicrobial peptide HS-1 inhibits dengue virus infection

Dengue virus (DENV) is an arbovirus that belongs to the Flaviviridae family. Studies reveal that peptides secreted by amphibians have many functions, such as antiviral and antimicrobial activities. As there is no antiviral drug effective against the DENV, the antiviral activity of a synthetic peptide called HS-1, derived from the secretion of the anuran Hypsiboas semilineatus, has been evaluated. The assays of neutralization in the Vero cells show a complete inhibition of infection of the serotypes 2 and 3. Furthermore, the direct action of peptides on the viral particle can be observed through atomic force microscopy. In vivo tests display 80% protection against the dengue-2 virus due to the presence of HS-1, which reveals its potential as an antiviral against the DENV.

Neurological Complications in a Polynesian Traveler with Dengue

In recent times, there has been an increased focus on mosquito-borne Flaviviruses, in particular dengue and Zika. With the reappearance of dengue in Hawai'i and the mainland United States (US), clinicians should be aware of both the common presentations of dengue, as well as other less common complications associated with the disease. Dengue can result in neurologic disorders such as encephalopathy, encephalitis, immune-mediated syndromes, neuromuscular dysfunction, and neuro-ophthalmologic disorders. We present an interesting case of dengue that initially presented with classic symptoms (arthropathy, biphasic fever, and rash) and subsequently developed into a neurologic movement disorder with muscle tightening and twitching of the face, chest, and extremities. We review and update the epidemiology, biology, the clinical presentations including the neurologic complications associated with dengue, as well as their management and areas of future study in this field.

"Preliminary Seroepidemiological survey of dengue infections in Pakistan, 2009-2014"

Background

Dengue virus is the causative agent of dengue fever, a vector borne infection which causes self-limiting to life threatening disease in humans. A sero-epidemiological study was conducted to understand the current epidemiology of dengue virus in Pakistan which is now known as a dengue endemic country after its first reported outbreak in 1994.

Methods

To investigate the prevalence of dengue virus in Pakistan during 2009-2014, a total of 9,493 blood samples were screened for the detection of anti-dengue IgM antibodies using ELISA. Clinical and demographic features available with hospital records were reviewed to ascertain mortalities related to dengue hemorrhagic shock syndrome.

Results

Out of 9,493 samples tested, 37% (3,504) were found positive for anti-dengue IgM antibodies. Of the seropositive cases, 73.6% (2,578/3,504) were male and 26.4% (926/3,504) were female. The highest number (382/929; 41.1%) of sero-positive cases was observed among the individuals of age group 31-40 years. The highest number of symptomatic cases was reported in October (46%; 4,400/9,493), and the highest number of sero-positive cases among symptomatic cases was observed in November (45.7%; 806/1,764). Mean annual patient incidence (MAPI) during 2009-2014 in Pakistan remained 0.30 with the highest annual patient incidence (11.03) found in Islamabad. According to the available medical case record, 472 dengue related deaths were reported during 2009-2014.

Conclusion

The data from earlier reports in Pakistan described the dengue virus incidence from limited areas of the country. Our findings are important considering the testing of clinical samples at a larger scale covering patients of vast geographical regions and warrants timely implementation of dengue vector surveillance and control programs.

Trial registration number

It is an epidemiological research study, so trial registration is not required.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-017-0258-6) contains supplementary material, which is available to authorized users.

Antiviral effect of compounds derived from the seeds of Mammea americana and Tabernaemontana cymosa on Dengue and Chikungunya virus infections

Background

The transmission of Dengue virus (DENV) and Chikungunya virus (CHIKV) has increased worldwide, due in part to the lack of a specific antiviral treatment. For this reason, the search for compounds with antiviral potential, either as licensed drugs or in natural products, is a research priority. The objective of this study was to identify some of the compounds that are present in Mammea americana (M. americana) and Tabernaemontana cymosa (T. cymosa) plants and, subsequently, to evaluate their cytotoxicity in VERO cells and their potential antiviral effects on DENV and CHIKV infections in those same cells.

Methods

Dry ethanolic extracts of M. americana and T. cymosa seeds were subjected to open column chromatographic fractionation, leading to the identification of four compounds: two coumarins, derived from M. americana; and lupeol acetate and voacangine derived from T. cymosa.. The cytotoxicity of each compound was subsequently assessed by the MTT method (at concentrations from 400 to 6.25 μg/mL). Pre- and post-treatment antiviral assays were performed at non-toxic concentrations; the resulting DENV inhibition was evaluated by Real-Time PCR, and the CHIKV inhibition was tested by the plating method. The results were analyzed by means of statistical analysis.

Results

The compounds showed low toxicity at concentrations ≤ 200 μg/mL. The compounds coumarin A and coumarin B, which are derived from the M. americana plant, significantly inhibited infection with both viruses during the implementation of the two experimental strategies employed here (post-treatment with inhibition percentages greater than 50%, p < 0.01; and pre-treatment with percentages of inhibition greater than 40%, p < 0.01). However, the lupeol acetate and voacangine compounds, which were derived from the T. cymosa plant, only significantly inhibited the DENV infection during the post-treatment strategy (at inhibition percentages greater than 70%, p < 0.01).

Conclusion

In vitro, the coumarins are capable of inhibiting infection by DENV and CHIKV (with inhibition percentages above 50% in different experimental strategies), which could indicate that these two compounds are potential antivirals for treating Dengue and Chikungunya fever. Additionally, lupeol acetate and voacangine efficiently inhibit infection with DENV, also turning them into promising antivirals for Dengue fever.

Treatment Effectiveness of Amantadine Against Dengue Virus Infection

BACKGROUND About 400 million cases of dengue, a mosquito-borne disease, are reported annually, but no drug is yet available for treatment. In 1988, at Feng Lin Clinic, Taiwan, we encountered about 10,000 cases and tested various drugs before confirming an antiviral effect of amantadine against dengue virus in vitro. After we administered amantadine to patients for 1-2 days, most achieved full remission. None experienced potentially life-threatening dengue hemorrhagic fever or dengue shock syndrome. Herein, we present 34 cases from recent clinical experience that show amantadine's unusual effect against dengue virus infection. CASE REPORT We divided 34 patients with symptoms of dengue fever, confirmed by a screening test, into 3 groups: 6 Category 1 patients received amantadine at onset, 21 Category 2 patients received amantadine within 2-6 days, and 7 Contrast group patients received no amantadine because they visited other clinics or were admitted to a large hospital. When Category 1 patients were treated with amantadine 100 mg 3 times per day, all symptoms dramatically subsided within 1-2 days. In Category 2 patients, most symptoms diminished within 1-2 days after starting the same regimen. In the Contrast group, all symptoms persisted 7 days after onset. White blood cell and platelet counts in Category 1 and 2 patients recovered to normal range, but remained below low normal in the Contrast group. CONCLUSIONS Amantadine is effective and should be given as soon as possible to stop the disease course if dengue fever is confirmed through screening or clinical signs and symptoms. A well-designed larger sample study is warranted to test this effectiveness.

Molecular docking NS4B of DENV 1-4 with known bioactive phyto-chemicals

Dengue disease is a global disease that has no effective treatment. The dengue virus (DENV) NS4B is a target for designing specific antivirals due to its importance in viral replication. Medicinal plants have been a savior for dengue virus as they consist of a class of phytochemicals having anti-viral activity and can pose a new approach ofstrong drug against viruses. The present study analyzes the activity of compounds against NS4B of DENV (1-4) serotypes. In this study Catechin, Cianidanol, Epicatechin, Eupatoretin, Glabranin, Laurifolin, DL-Catechin, astherapeutic agents were filtered by using Lipinski rule's five and the drug-likeness property of these agents were used for assessment of pharmacological properties. The molecular docking results presented the 2-D structures of bioactive complex, which interacted with especially conserved residues of target domains. Interestingly, we find the Catechin, Laurifolin, Cianidanol have highest binding energy against NS4B in DENV-1,2,4 which is evident by the formation of more hydrogen bonds with the amino acid residues at the binding site of the receptor. Our results revealed that the bioactive compound, especially Catechin has significant anti-dengue activities. In addition, this study may be helpful in further experimental investigations.

Glycosphingolipid GM3 is Indispensable for Dengue Virus Genome Replication

Dengue virus (DENV) causes the most prevalent arthropod-borne viral disease of humans worldwide. Glycosphingolipids (GSLs) are involved in virus infection by regulating various steps of viral-host interaction. However, the distinct role of GSLs during DENV infection remains unclear. In this study, we used mouse melanoma B16 cells and their GSL-deficient mutant counterpart GM95 cells to study the influence of GSLs on DENV infection. Surprisingly, GM95 cells were highly resistant to DENV infection compared with B16 cells. Pretreatment of B16 cells with synthetase inhibitor of GM3, the most abundant GSLs in B16 cells, or silencing GM3 synthetase T3GAL5, significantly inhibited DENV infection. DENV attachment and endocytosis were not impaired in GM95 cells, but DENV genome replication was obviously inhibited in GM95 cells compared to B16 cells. Furthermore, GM3 was colocalized with DENV viral replication complex on endoplasmic reticulum (ER) inside the B16 cells. Finally, GM3 synthetase inhibitor significantly reduced the mortality rate of suckling mice that challenged with DENV by impairing the viral replication in mouse brain. Taken together, these data indicated that GM3 was not required for DENV attachment and endocytosis, however, essential for viral genome replication. Targeting GM3 could be a novel strategy to inhibit DENV infection.

The C-terminal 50 amino acid residues of dengue NS3 protein are important for NS3-NS5 interaction and viral replication

Dengue virus multifunctional proteins NS3 protease/helicase and NS5 methyltransferase/RNA-dependent RNA polymerase form part of the viral replication complex and are involved in viral RNA genome synthesis, methylation of the 5'-cap of viral genome, and polyprotein processing among other activities. Previous studies have shown that NS5 residue Lys-330 is required for interaction between NS3 and NS5. Here, we show by competitive NS3-NS5 interaction ELISA that the NS3 peptide spanning residues 566-585 disrupts NS3-NS5 interaction but not the null-peptide bearing the N570A mutation. Small angle x-ray scattering study on NS3(172-618) helicase and covalently linked NS3(172-618)-NS5(320-341) reveals a rigid and compact formation of the latter, indicating that peptide NS5(320-341) engages in specific and discrete interaction with NS3. Significantly, NS3:Asn-570 to alanine mutation introduced into an infectious DENV2 cDNA clone did not yield detectable virus by plaque assay even though intracellular double-stranded RNA was detected by immunofluorescence. Detection of increased negative-strand RNA synthesis by real time RT-PCR for the NS3:N570A mutant suggests that NS3-NS5 interaction plays an important role in the balanced synthesis of positive- and negative-strand RNA for robust viral replication. Dengue virus infection has become a global concern, and the lack of safe vaccines or antiviral treatments urgently needs to be addressed. NS3 and NS5 are highly conserved among the four serotypes, and the protein sequence around the pinpointed amino acids from the NS3 and NS5 regions are also conserved. The identification of the functionally essential interaction between the two proteins by biochemical and reverse genetics methods paves the way for rational drug design efforts to inhibit viral RNA synthesis.

Highly conserved residues in the helical domain of dengue virus type 1 precursor membrane protein are involved in assembly, precursor membrane (prM) protein cleavage, and entry

The envelope and precursor membrane (prM) proteins of dengue virus (DENV) are present on the surface of immature virions. During maturation, prM protein is cleaved by furin protease into pr peptide and membrane (M) protein. Although previous studies mainly focusing on the pr region have identified several residues important for DENV replication, the functional role of M protein, particularly the α-helical domain (MH), which is predicted to undergo a large conformational change during maturation, remains largely unknown. In this study, we investigated the role of nine highly conserved MH domain residues in the replication cycle of DENV by site-directed mutagenesis in a DENV1 prME expression construct and found that alanine substitutions introduced to four highly conserved residues at the C terminus and one at the N terminus of the MH domain greatly affect the production of both virus-like particles and replicon particles. Eight of the nine alanine mutants affected the entry of replicon particles, which correlated with the impairment in prM cleavage. Moreover, seven mutants were found to have reduced prM-E interaction at low pH, which may inhibit the formation of smooth immature particles and exposure of prM cleavage site during maturation, thus contributing to inefficient prM cleavage. Taken together, these results are the first report showing that highly conserved MH domain residues, located at 20-38 amino acids downstream from the prM cleavage site, can modulate the prM cleavage, maturation of particles, and virus entry. The highly conserved nature of these residues suggests potential targets of antiviral strategy.

A crystal structure of the dengue virus non-structural protein 5 (NS5) polymerase delineates interdomain amino acid residues that enhance its thermostability and de novo initiation activities

The dengue virus (DENV) non-structural protein 5 (NS5) comprises an N-terminal methyltransferase and a C-terminal RNA-dependent RNA polymerase (RdRp) domain. Both enzymatic activities form attractive targets for antiviral development. Available crystal structures of NS5 fragments indicate that residues 263-271 (using the DENV serotype 3 numbering) located between the two globular domains of NS5 could be flexible. We observed that the addition of linker residues to the N-terminal end of the DENV RdRp core domain stabilizes DENV1-4 proteins and improves their de novo polymerase initiation activities by enhancing the turnover of the RNA and NTP substrates. Mutation studies of linker residues also indicate their importance for viral replication. We report the structure at 2.6-Å resolution of an RdRp fragment from DENV3 spanning residues 265-900 that has enhanced catalytic properties compared with the RdRp fragment (residues 272-900) reported previously. This new orthorhombic crystal form (space group P21212) comprises two polymerases molecules arranged as a dimer around a non-crystallographic dyad. The enzyme adopts a closed "preinitiation" conformation similar to the one that was captured previously in space group C2221 with one molecule per asymmetric unit. The structure reveals that residues 269-271 interact with the RdRp domain and suggests that residues 263-268 of the NS5 protein from DENV3 are the major contributors to the flexibility between its methyltransferase and RdRp domains. Together, these results should inform the screening and development of antiviral inhibitors directed against the DENV RdRp.

Dengue: a growing menace -- a snapshot of recent facts, figures & remedies

Dengue is specially owing to inadequate water supply and poor solid waste management , which are favorable for multiplication of the main vectors including the Aedes ageypti coupled with lack of proven anti viral therapy and no proven efficient vaccine .there are many cases of both dengue shock syndrome and dengue haemmorhagic fever making it a major public health burden sending ominous signal resulting both rising morbidity & mortality, deleterious effect on DALY [disability adjusted life year] & QALY [quality adjusted life year] & though it affect all section of society ,still it affect the poor & underprivileged section more, thereby growing menace in public health in general & in developing countries in particular.