Secreted dengue virus NS1 from infection is predominantly dimeric and in complex with high-density lipoprotein

Severe dengue infections are characterized by endothelial dysfunction shown to be associated with the secreted nonstructural protein 1 (sNS1), making it an attractive vaccine antigen and biotherapeutic target. To uncover the biologically relevant structure of sNS1, we obtained infection-derived sNS1 (isNS1) from dengue virus (DENV)-infected Vero cells through immunoaffinity purification instead of recombinant sNS1 (rsNS1) overexpressed in insect or mammalian cell lines. We found that isNS1 appeared as an approximately 250 kDa complex of NS1 and ApoA1 and further determined the cryoEM structures of isNS1 and its complex with a monoclonal antibody/Fab. Indeed, we found that the major species of isNS1 is a complex of the NS1 dimer partially embedded in a high-density lipoprotein (HDL) particle. Crosslinking mass spectrometry studies confirmed that the isNS1 interacts with the major HDL component ApoA1 through interactions that map to the NS1 wing and hydrophobic domains. Furthermore, our studies demonstrated that the sNS1 in sera from DENV-infected mice and a human patient form a similar complex as isNS1. Our results report the molecular architecture of a biological form of sNS1, which may have implications for the molecular pathogenesis of dengue.

Dual RNA-Seq reveals transcriptionally active microbes (TAMs) dynamics in the serum of dengue patients associated with disease severity

Introduction

Dengue virus (DENV) is a flavivirus that has emerged as a global health threat, characterized by either asymptomatic or mild self-limiting febrile illness, but a subset of DENV outbreaks have been associated with severe disease. Studies have looked into the host immune response and dengue viral load during infection. However, it remains unknown how the active microbial isolates modulate the dengue viral infection. In this study, we demonstrate the significance of in-depth analysis of microbiota composition in the serum samples of dengue-infected patients.

Materials and methods

RNA was extracted from the serum samples collected from 24 dengue positive patients. The human mapped reads generated through RNA-Sequencing (RNA-Seq) were removed, while the unmapped (non-human) reads were employed for microbial taxonomic classification using Kraken2 and Bracken2. Further, we assessed the initial blood parameters analyzing the complete blood count (CBC) profile of the patients.

Results

Findings revealed differential abundance of commensals and pathogenic microbes in the early febrile period of hospitalized dengue patients, segregated into, High Viral Reads (HVR) and Low Viral Reads (LVR). The Campylobacter genus was abundant in the HVR whereas Lactobacillus dominated the LVR patients. At species level, the microbiota of HVR exhibited higher abundance of unique potential opportunistic microbes, compared to the commensal microbes' enrichment in the LVR patients'. We hypothesize that the DENV might alter the microbiota composition as observed by the increase in preponderance of opportunistic pathogens and an absence of commensals in the HVR. The presence of commensals in the LVR might explain, i) overall lower dengue viral reads compared to the HVR, and ii) shift in lymphocytes (high) and neutrophils (low) counts; resulting in a comparatively milder clinical manifestation in this group. Our findings may help in understanding the co-infection aspect that will be important to develop dengue therapeutics and vaccines.

Discussion

This study highlights the potential of the unexplored roles of the TAMs in modulating the dengue disease severity using the metatranscriptomic sequencing. This study serves to enhance our understanding of the distinctive microbial and hematologic signatures in the early infection stage that differentiate patients with high viral reads patients from those with low dengue viral reads.

Nanomedicine as a potential novel therapeutic approach against the dengue virus

Dengue is an arbovirus infection which is transmitted by Aedes mosquitoes. Its prompt detection and effective treatment is a global health challenge. Various nanoparticle-based vaccines have been formulated to present immunogen (antigens) to instigate an immune response or prevent virus spread, but no specific treatment has been devised. This review explores the role of nanomedicine-based therapeutic agents against dengue virus, taking into consideration the applicable dengue virus assays that are sensitive, specific, have a short turnaround time and are inexpensive. Various kinds of metallic, polymeric and lipid nanoparticles with safe and effective profiles present an alternative strategy that could provide a better remedy for eradicating the dengue virus.

A stochastic B cell affinity maturation model to characterize mechanisms of protection for tetravalent dengue vaccine constructs

Dengue annually infects millions of people from a regionally and seasonally varying dengue virus population circulating as four distinct serotypes. Effective protection against dengue infection and disease requires tetravalent vaccine formulations to stimulate a balanced protective immune response to all four serotypes. However, this has been a challenge to achieve, and several clinical trials with different leading vaccine candidates have demonstrated unbalanced replication and interference of interindividual serotype components, leading to low efficacy and enhanced disease severity for dengue-naïve populations. Production of serotype-specific neutralizing antibodies is largely viewed as a correlate of protection against severe dengue disease. However, the underlying mechanisms that lead to these protective immune responses are not clearly elucidated. In this work, using a stochastic model of B cell affinity maturation, we tested different live-attenuated vaccine constructs with varied viral replication rates and contrasted the initiation and progress of adaptive immune responses during tetravalent vaccination and after dengue virus challenge. Comparison of our model simulations across different disease-severity levels suggested that individual production of high levels of serotype-specific antibodies together with a lower cross-reactive antibody are better correlates for protection. Furthermore, evolution of these serotype-specific antibodies was dependent on the percent of viral attenuation in the vaccine, and production of initial B cell and T cell populations pre- and post-secondary dengue infection was crucial in providing protective immunity for dengue-naïve populations. Furthermore, contrasting disease severity with respect to different dengue serotypes, our model simulations showed that tetravalent vaccines fare better against DENV-4 serotype when compared to other serotypes.

Plasmablast Expansion Following the Tetravalent, Live-Attenuated Dengue Vaccine Butantan-DV in DENV-Naïve and DENV-Exposed Individuals in a Brazilian Cohort

An effective vaccine against the dengue virus (DENV) should induce a balanced, long-lasting antibody (Ab) response against all four viral serotypes. The burst of plasmablasts in the peripheral blood after vaccination may reflect enriched vaccine-specific Ab secreting cells. Here we characterize the acute plasmablast responses from naïve and DENV-exposed individuals following immunization with the live attenuated tetravalent (LAT) Butantan DENV vaccine (Butantan-DV). The frequency of circulating plasmablasts was determined by flow cytometric analysis of fresh whole blood specimens collected from 40 participants enrolled in the Phase II Butantan-DV clinical trial (NCT01696422) before and after (days 6, 12, 15 and 22) vaccination. We observed a peak in the number of circulating plasmablast at day 15 after vaccination in both the DENV naïve and the DENV-exposed vaccinees. DENV-exposed vaccinees experienced a significantly higher plasmablast expansion. In the DENV-naïve vaccinees, plasmablasts persisted for approximately three weeks longer than among DENV-exposed volunteers. Our findings indicate that the Butantan-DV can induce plasmablast responses in both DENV-naïve and DENV-exposed individuals and demonstrate the influence of pre-existing DENV immunity on Butantan DV-induced B-cell responses.

Assessing Aedes aegypti candidate genes during viral infection and Wolbachia-mediated pathogen blocking

One approach to control dengue virus transmission is the symbiont Wolbachia, which limits viral infection in mosquitoes. Despite plans for its widespread use in Aedes aegypti, Wolbachia's mode of action remains poorly understood. Many studies suggest that the mechanism is likely multifaceted, involving aspects of immunity, cellular stress and nutritional competition. A previous study from our group used artificial selection to identify a new mosquito candidate gene related to viral blocking; alpha-mannosidase-2a (alpha-Mann-2a) with a predicted role in protein glycosylation. Protein glycosylation pathways tend to be involved in complex host-viral interactions; however, the function of alpha-mannosidases has not been described in mosquito-virus interactions. We examined alpha-Mann-2a expression in response to virus and Wolbachia infections and whether reduced gene expression, caused by RNA interference, affected viral loads. We show that dengue virus (DENV) infection affects the expression of alpha-Mann-2a in a tissue- and time-dependent manner, whereas Wolbachia infection had no effect. In the midgut, DENV prevalence increased following knockdown of alpha-Mann-2a expression in Wolbachia-free mosquitoes, suggesting that alpha-Mann-2a interferes with infection. Expression knockdown had the same effect on the togavirus chikungunya virus, indicating that alpha-Mann-2a may have broad antivirus effects in the midgut. Interestingly, we were unable to knockdown the expression in Wolbachia-infected mosquitoes. We also provide evidence that alpha-Mann-2a may affect the transcriptional level of another gene predicted to be involved in viral blocking and cell adhesion; cadherin87a. These data support the hypothesis that glycosylation and adhesion pathways may broadly be involved in viral infection in Ae. aegypti.

Identification of geographic clusters for temporal heterogeneity with application to dengue surveillance

Identifying transmission of hot spots with temporal trends is important for reducing infectious disease propagation. Cluster analysis is a particularly useful tool to explore underlying stochastic processes between observations by grouping items into categories by their similarity. In a study of epidemic propagation, clustering geographic regions that have similar time series could help researchers track diffusion routes from a common source of an infectious disease. In this article, we propose a two‐stage scan statistic to classify regions into various geographic clusters by their temporal heterogeneity. The proposed scan statistic is more flexible than traditional methods in that contiguous and nonproximate regions with similar temporal patterns can be identified simultaneously. A simulation study and data analysis for a dengue fever infection are also presented for illustration.

In Acute Dengue Infection, High TIM-3 Expression May Contribute to the Impairment of IFNγ Production by Circulating Vδ2 T Cells

γδ T cells are innate cells able to quickly eliminate pathogens or infected/tumoral cells by their antiviral and adjuvancy activities. The role of γδ T cells during Dengue Viral Infection (DENV) infection is not fully elucidated. Nevertheless, human primary γδ T cells have been shown to kill in vitro DENV-infected cells, thus highlighting their possible antiviral function. The aim of this work was to characterize the phenotype and function of Vδ2 T cells in DENV patients. Fifteen DENV patients were enrolled for this study and peripheral blood mononuclear cells (PBMC) were used to analyze Vδ2-T-cell frequency, differentiation profile, activation/exhaustion status, and functionality by multiparametric flow cytometry. Our data demonstrated that DENV infection was able to significantly reduce Vδ2-T-cell frequency and to increase their activation (CD38 and HLA-DR) and exhaustion markers (PD-1 and TIM-3). Furthermore, Vδ2 T cells showed a reduced capability to produce IFN-γ after phosphoantigenic stimulation that can be associated to TIM-3 expression. Several studies are needed to depict the possible clinical impact of γδ-T-cell impairment on disease severity and to define the antiviral and immunoregulatory activities of γδ T cells in the first phases of infection.

Kinetic Changes of Peripheral Blood Monocyte Subsets and Expression of Co-Stimulatory Molecules during Acute Dengue Virus Infection

Monocytes, one of the main target cells for dengue virus (DENV) infection, contribute to the resolution of viremia and to pathogenesis. We performed a longitudinal study by a detailed phenotypic comparison of classical (CD14++CD16−, non-classical (CD14+CD16++) and intermediate (CD14++CD16+) monocyte subsets in blood samples from dengue fever (DF) to the severe dengue hemorrhagic fever (DHF) and healthy individuals. Various costimulatory molecules of CD40, CD80, CD86 and inducible costimulatory ligand (ICOSL) expressed on these three monocyte subsets were also analyzed. DENV-infected patients showed an increase in the frequency of intermediate monocytes and a decrease in the classical monocytes when compared to healthy individuals. Although these differences did not correlate with disease severity, changes during the early phase of infection gradually returned to normal in the defervescence phase. Moreover, decreased frequency of classical monocytes was associated with a significant up-regulation of co-stimulatory molecules CD40, CD86 and ICOSL. Kinetics of these co-stimulatory molecule-expressing classical monocytes showed different patterns throughout the sampling times of acute DENV infection. Different distribution of monocyte subsets and their co-stimulatory molecules in the peripheral blood during acute infection might exacerbate immune responses like cytokine storms and ADE, and future studies on intracellular molecular pathways utilized by these monocyte linages are warranted.

Stochastic Model of the Adaptive Immune Response Predicts Disease Severity and Captures Enhanced Cross-Reactivity in Natural Dengue Infections

The dengue virus circulates as four distinct serotypes, where a single serotype infection is typically asymptomatic and leads to acquired immunity against that serotype. However, the developed immunity to one serotype is thought to underlie the severe manifestation of the disease observed in subsequent infections from a different serotype. We developed a stochastic model of the adaptive immune response to dengue infections. We first delineated the mechanisms initiating and sustaining adaptive immune responses during primary infections. We then contrasted these immune responses during secondary infections of either a homotypic or heterotypic serotype to understand the role of pre-existing and reactivated immune pathways on disease severity. Comparison of non-symptomatic and severe cases from heterotypic infections demonstrated that overproduction of specific antibodies during primary infection induces an enhanced population of cross-reactive antibodies during secondary infection, ultimately leading to severe disease manifestations. In addition, the level of disease severity was found to correlate with immune response kinetics, which was dependent on beginning lymphocyte levels. Our results detail the contribution of specific lymphocytes and antibodies to immunity and memory recall that lead to either protective or pathological outcomes, allowing for the understanding and determination of mechanisms of protective immunity.

Coincidence of fever following COVID-19 vaccine and endemic tropical diseases: a challenge to clinicians during the global rollout of COVID-19 vaccination

Coincidence of fever following COVID-19 vaccine and endemic tropical diseases may occur during the global rollout of COVID-19 vaccination. Clinicians should aware of this scenario when dealing with fever post-vaccination to prevent delayed diagnosis.

Stem Cell Therapy in Dengue Virus-Infected BALB/C Mice Improves Hepatic Injury

Extensive clinical efforts have been made to control the severity of dengue diseases; however, the dengue morbidity and mortality have not declined. Dengue virus (DENV) can infect and cause systemic damage in many organs, resulting in organ failure. Here, we present a novel report showing a tailored stem-cell-based therapy that can aid in viral clearance and rescue liver cells from further damage during dengue infection. We administered a combination of hematopoietic stem cells and endothelial progenitor cells in a DENV-infected BALB/c mouse model and found that delivery of this cell cocktail had improved their liver functions, confirmed by hematology, histopathology, and next-generation sequencing. These stem and progenitor cells can differentiate into target cells and repair the damaged tissues. In addition, the regime can regulate endothelial proliferation and permeability, modulate inflammatory reactions, enhance extracellular matrix production and angiogenesis, and secrete an array of growth factors to create an enhanced milieu for cell reparation. No previous study has been published on the treatment of dengue infection using stem cells combination. In conclusion, dengue-induced liver damage was rescued by administration of stem cell therapy, with less apoptosis and improved repair and regeneration in the dengue mouse model.

Acute Encephalopathy with Biphasic Seizures and Late Reduced Diffusion Associated with Dengue Infection in a Child

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a clinico-radiological syndrome in children secondary to viral or bacterial infections. The causes include viral (influenza, human herpes virus-6, adenovirus, rota) as well as bacterial infections. However, AESD with dengue infection has not been reported earlier. Here, we present an infant with dengue infection and AESD which recovered completely following treatment with intravenous human immunoglobulin therapy. A 9-month-old girl presented with seizures following fever and loose stools. Seizures recurred after 2 days of seizure-free interval. Cerebrospinal fluid analysis was not contributory. Dengue infection was confirmed by lab tests. Magnetic resonance imaging brain after the second seizure revealed diffusion restriction involving the bilateral frontal and parietal white matter, both hemispheres with a typical central perisylvian sparing lesion suggestive of AESD. This case report expands the reported spectrum of neurological manifestations of dengue infection.

Dengue Virus Infection Presenting as Membranoproliferative Glomerulonephritis Type 1

The renal complications of dengue virus infection cover a wide spectrum of manifestations from acute kidney injury to glomerular injury with nephritic/nephrotic syndrome. Majority of cases remain symptom free and show full recovery. We present a 61-year-old previously healthy male who developed a pyrexial illness with haemolytic anaemia that was diagnosed on the basis of a positive serological test as a case of dengue fever. He received supportive treatment and showed general recovery except for his renal dysfunction that showed persistent proteinuria at 14 gm/24 hours. A kidney biopsy revealed membranoproliferative glomerulonephritis type 1 (MPGN-l). Complete remission was achieved by steroids and mycophenolate mofetil therapy. We provide convincing biopsy evidence that dengue virus is yet another viral cause of MPGN-l and also document its successful management with mycophenolate mofetil and steroids therapy.

Anti-DENV and Anti-Dengue Vector Activity of Some Heterocyclic Scaffolds

Dengue is a major health threat related to arbovirus and is endemic in more than 100 countries with an annual estimated above 390 million incidences of infection all around the world. During the period 1996-2015, a considerable increase in the number of dengue cases (more than 500%) was reported in India. Information about dengue disease burden, its prevalence, incidence and geographic distribution is critical in planning appropriate control measures against dengue fever. Till date, no specific treatment for dengue fever is available in any system of medicine, which can be accepted globally. Therefore, safe, cost-effective, and efficacious agents possessing anti-viral potential against dengue virus are needed to be searched in order to fight the dengue infection globally. The aim of the present review is to systematically revise the published research work available concerning the development and evaluation of some heterocyclic scaffolds in the management of dengue.

Dengue Infection Complicated by Hemophagocytic Lymphohistiocytosis: Experiences From 180 Patients With Severe Dengue

BACKGROUND

Globally, ~500 000 people with severe dengue (SD) require hospitalization yearly; ~12 500 (2.5%) die. Secondary hemophagocytic lymphohistiocytosis (sHLH) is a potentially fatal hyperinflammatory condition for which HLH-directed therapy (as etoposide and dexamethasone) can be life-saving. Prompted by the high mortality in SD and the increasing awareness that patients with SD may develop sHLH, our objectives were to (1) determine the frequency of dengue-HLH in SD, (2) describe clinical features of dengue-HLH, (3) assess mortality rate in SD and dengue-HLH, and (4) identify mortality-associated risk factors in SD.

METHODS

A 5-year retrospective single-center study in all adult patients with SD admitted to a tertiary intensive care unit in Malaysia.

RESULTS

Thirty-nine of 180 (22%) patients with SD died. Twenty-one of 180 (12%) had HLH defined as an HLH probability ≥70% according to histo score (HScore); 9 (43%) died. Similarly, 12 of 31 (39%) fulfilling ≥4 and 7 of 9 (78%) fulfilling ≥5 HLH-2004 diagnostic criteria died. Peak values of aspartate aminotransferase (AST), alanine aminotransferase, lactate dehydrogenase, and creatinine correlated to fatality (odds ratios [ORs], 2.9, 3.4, 5.8, and 31.9; all P < .0001), as did peak ferritin (OR, 2.5; P = .0028), nadir platelets (OR, 1.9; P = .00068), hepatomegaly (OR, 2.9; P = .012), and increasing age (OR, 1.2; P = .0043). Multivariable logistic regression revealed peak AST (OR, 2.8; P = .0019), peak creatinine (OR, 7.3; P = .0065), and SOFA (Sequential Organ Failure Assessment) score (OR, 1.4; P = .0051) as independent risk factors of death.

CONCLUSIONS

Be observant of dengue-HLH due to its high mortality. A prospective study is suggested on prompt HLH-directed therapy in SD patients with hyperinflammation and evolving multiorgan failure at risk of developing dengue-HLH.

Role of Platelet Cytokines in Dengue Virus Infection

Platelets are anucleated blood cells derived from bone marrow megakaryocytes and play a crucial role in hemostasis and thrombosis. Platelets contain specialized storage organelles, called alpha-granules, contents of which are rich in cytokines such as C-X-C Motif Chemokine Ligand (CXCL) 1/4/7, (C-C motif) ligand (CCL) 5/3, CXCL8 (also called as interleukin 8, IL-8), and transforming growth factor β (TGF-β). Activation of platelets lead to degranulation and release of contents into the plasma. Platelet activation is a common event in many viral infections including human immunodeficiency virus (HIV), H1N1 influenza, Hepatitis C virus (HCV), Ebola virus (EBV), and Dengue virus (DENV). The cytokines CXCL8, CCL5 (also known as Regulated on Activation, Normal T Expressed and Secreted, RANTES), tumor necrosis factor α (TNF-α), CXCL1/5 and CCL3 released, promote development of a pro-inflammatory state along with the recruitment of other immune cells to the site of infection. Platelets also interact with Monocytes and Neutrophils and facilitate their activation to release different cytokines which further enhances inflammation. Upon activation, platelets also secrete factors such as CXCL4 (also known as platelet factor, PF4), CCL5 and fibrinopeptides which are critical regulators of replication and propagation of several viruses in the host. Studies suggest that CXCL4 can both inhibit as well as enhance HIV1 infection. Data from our lab show that CXCL4 inhibits interferon (IFN) pathway and promotes DENV replication in monocytes in vitro and in patients significantly. Inhibition of CXCL4 mediated signaling results in increased IFN production and suppressed DENV and JEV replication in monocytes. In this review, we discuss the role of platelets in viral disease progression with a focus on dengue infection.

Evaluating the validity of dengue clinical-epidemiological criteria for diagnosis in patients residing in a Brazilian endemic area

BACKGROUND

We evaluated the validity of clinical diagnosis compared with laboratory diagnosis of dengue in a retrospective sample of patients in São José do Rio Preto, Brazil.

METHODS

Our sample included 148 299 clinically (56.3%) or laboratory-diagnosed (43.7%) dengue cases. We compared the sensitivity, specificity, positive and negative predictive value (PPV and NPV) of dengue patients' demographic and clinical characteristics with laboratory-based diagnosis. We used logistic regressions to estimate the correlation between clinical and laboratory diagnosis of dengue and a full set of dengue signs and symptoms.

RESULTS

We found substantial variability in sensitivity and specificity of signs and symptoms ranging from 0.8-81.1 and 21.5-99.6, respectively. Thrombocytopenia exhibited the highest PPV (92.0) and lowest NPV (42.2) and was the only symptom showing agreement with laboratory-confirmed dengue (φ = 0.38). The presence of exanthema and thrombocytopenia led to a greater likelihood of concordant clinical and laboratory diagnoses (exanthema: OR: 4.23; 95% CI: 2.09 to 8.57; thrombocytopenia: OR: 4.02; 95% CI: 1.32 to 12.27).

CONCLUSIONS

We found substantial variation in sensitivity, specificity, PPV and NPV of dengue signs and symptoms. For accuracy, clinical and laboratory diagnosis of dengue should be performed concurrently. When laboratory tests are not available, we suggest focusing on the clinical manifestations most associated with dengue.

The use of immature platelet fraction to predict time to platelet recovery in patients with dengue infection

Background: In dengue infection, knowing time to platelet recovery is essential for optimal management.Aims: To determine a predictor for platelet recovery in patients with dengue infection.Methods: Platelet count and immature platelet fraction (IPF) from daily blood samples of patients with dengue infection during hospitalisation and 1-4 weeks after discharge were retrospectively analysed. The levels of patients' IPF were compared with normal controls recruited from healthy children with normal platelet counts.Results: A total of 244 EDTA blood samples were collected daily from 64 patients (45 males) with dengue infection (36 dengue fever, 28 dengue haemorrhagic fever) during hospitalisation and after discharge from the hospital. They did not receive any platelet concentrate transfusion. The median IPF among normal children was 3.6% with a 95 percentile of 9.9%. In dengue patients, an IPF of ≥10.0% after defervescence was associated with a subsequent platelet count of ≥60 × 10⁹/L within 72 hours.Conclusion: In patients with dengue infection, IPF ≥10.0% after defervescence is a predictor of subsequent platelet recovery to a haemostatic level ≥60 × 10⁹/L within 72 hours.

First report of collapsing variant of focal segmental glomerulosclerosis triggered by arbovirus: dengue and Zika virus infection

Background

The collapsing variant of focal segmental glomerulosclerosis (FSGS) is the most aggressive form of FSGS and is characterized by at least one glomerulus with segmental or global collapse and overlying podocyte hypertrophy and hyperplasia. Viruses can act as aetiological agents of secondary FSGS. This study aims to establish an aetiological link between dengue virus (DENV) infection and the collapsing variant of FSGS and to analyse possible influences of the apolipoprotein 1 (APOL1) gene risk alleles on the disease.

Methods

Biopsies and medical records were gathered from 700 patients of the Instituto de Nefropatologia, Belo Horizonte, Brazil. Screening for the collapsing variant of FSGS was performed and serological, immunohistochemical, tissue polymerase chain reaction (PCR) and genetic analysis were conducted.

Results

Eight patients were identified with positive DENV serology and negative serological and/or tissue markers for hepatitis B virus, hepatitis C virus, Epstein–Barr virus, human immunodeficiency virus, cytomegalovirus and parvovirus B19. In PCR analysis, six patients had positive markers for DENV strain genetic material, one patient had positive markers for co-infection of Zika virus (ZIKV) and DENV and one patient had positive markers only for ZIKV infection. Six of the eight patients did not show risk alleles of the APOL1 gene. One patient had only one risk allele (G1) and the sample from another did not contain enough DNA for genetic analysis to be performed.

Conclusions

This study provided strong evidence that DENV can infect renal tissue and possibly functions as a second hit to the development of the collapsing variant of FSGS. Nonetheless, this study also highlights the possible implication of ZIKV infection in FSGS and supports the argument that risk alleles of the APOL1 gene may not be implicated in the susceptibility to FSGS in these patients.

Successful treatment of thrombotic microangiopathy associated with dengue infection: A case report and literature review

Dengue infection has been associated with multiple renal complications, including glomerulonephritis, acute tubular necrosis, tubulointerstitial nephritis, and thrombotic microangiopathy (TMA), this last one being a rare complication of dengue, with only a few reported cases. TMA associated with dengue can be explained by an alteration in the activity of the enzyme ADAMTS13, leading to thrombotic thrombocytopenic purpura; or it can be secondary to direct or indirect endothelial injury by the virus, which leads to hemolytic uremic syndrome. Here, we present a case of severe TMA, not related to ADAMTS13, which was clearly associated with dengue infection.

Differences in activation and tissue homing markers of natural killer cell subsets during acute dengue infection

Dengue virus (DENV) infection is considered one of the most important mosquito-borne diseases. It causes a spectrum of illness that could be due to qualitative and/or quantitative difference(s) of the natural killer (NK) cell responses during acute DENV infection. This view prompted us to perform a detailed phenotypic comparative characterization of NK cell subsets from DENV-infected patients with dengue fever (DF), patients with dengue haemorrhagic fever (DHF) and healthy controls. The activation/differentiation molecules, CD69 and CD57 and a variety of tissue homing molecules were analysed on the CD56^hi CD16^- and CD56^lo CD16⁺ NK cells. Although there was no increase in the frequency of the total NK cells during DENV infection compared with the healthy individuals, there was a significant increase in the frequency of the CD56^hi CD16^- subset and the frequency of CD69 expression by both NK cell subsets during the febrile phase of infection. We also found an increase in the frequencies of cells expressing CD69 and CD57 in the CD56^lo CD16⁺ subset compared with those in the CD56^hi CD16^- subset. Moreover, although the CD56^lo CD16⁺ subset contained a high frequency of cells expressing skin-homing markers, the CD56^hi CD16^- subset contained a high frequency of cells expressing bone marrow and lymph node trafficking markers. Interestingly, no differences of these NK cell subsets were noted in samples from patients with DF versus those with DHF. These findings suggest that activation and differentiation and the patterns of tissue homing molecules of the two major NK cell subsets are different and that these might play a critical role in the immune response against acute DENV infection.

Association of Endothelial Glycocalyx and Tight and Adherens Junctions With Severity of Plasma Leakage in Dengue Infection

Background.

The role of vascular endothelial (VE) components in dengue infection with plasma leakage is unknown. Therefore, we conducted a study to determine the adjusted association of the endothelial glycocalyx layer (EGL) and tight and adherens junction markers with plasma leakage.

Methods.

A prospective observational study was conducted at Cipto Mangunkusumo Hospital and Persahabatan Hospital, Jakarta, Indonesia. Adult dengue patients admitted to the hospital on the third day of fever from November 2013 through August 2015 were included in the study. Multiple regression analysis was used to determine the adjusted association of the VE biomarkers with the severity of the plasma leakage.

Results.

A total of 103 dengue-infected patients participated in the study. In the critical phase, levels of syndecan-1 (odds ratio [OR] = 1.004; 95% confidence interval [CI] = 1.001–1.007) and chondroitin sulfate (OR = 1.157; 95% CI = 1.025–1.307) had an adjusted association with plasma leakage, whereas levels of syndecan-1 (OR = 1.004; 95% CI = 1.000–1.008) and claudin-5 (OR = 1.038; 95% CI = 1.004–1.074) had an adjusted association with severe plasma leakage.

Conclusions.

In dengue-infected patients, elevated levels of syndecan-1 and chondroitin sulfate are strongly associated with plasma leakage, and elevated levels of syndecan-1 and claudin-5 are strongly associated with severe plasma leakage.

Is excessive acetaminophen intake associated with transaminitis in adult patients with dengue fever?

BACKGROUND

Dengue, an endemic infection causing severe flu-like symptoms and fever, is often treated with high-dose acetaminophen that can exceed recommended daily dosages. This leads to hepatotoxicity, although the underlying mechanism is poorly understood. We hypothesised that excessive acetaminophen causes hepatic toxicity in dengue patients.

AIMS

To investigate a correlation between elevated serum transaminases and excessive acetaminophen intake, and other aggravating factors of liver injury in dengue cases.

METHODS

This prospective observational study obtained blood samples from 150 participants with acute febrile illness for dengue serological tests, blood counts, and the detection of serum transaminases and acetaminophen levels. Other factors were determined by questionnaire.

RESULTS

Of 150 participants enrolled, 77 had dengue fever. Abnormally high serum aspartate transaminase and alanine transaminase levels were present in 97.0% and 75.3% of dengue cases respectively. Multivariate analysis of cases with increased serum transaminases more than threefold normal upper limits indicated that male gender (odds ratio (OR) = 3.62, 95% confidence interval (CI) 1.38-9.42) and consuming >8 g acetaminophen orally (OR = 4.62, 95% CI 1.37-13.18) correlated with transaminitis. No correlation was found for other factors such as age, fever day at presentation, body mass index, alcohol intake or dengue severity classification (all P > 0.05). Chronic alcohol consumption was higher in non-dengue (2.6%) versus dengue cases (27.8%) (P < 0.01).

CONCLUSIONS

Most dengue patients had mild-to-moderate transaminitis. Male gender and acetaminophen >8 g were associated with increased serum transaminases. Thus, 1000 mg acetaminophen every 8 h or <3000 mg/day is recommended for dengue cases. Chronic alcohol consumption might be protective against dengue infection.

Dengue NS1 antigen contributes to disease severity by inducing interleukin (IL)-10 by monocytes

Both dengue NS1 antigen and serum interleukin (IL)-10 levels have been shown to associate with severe clinical disease in acute dengue infection, and IL-10 has also been shown to suppress dengue-specific T cell responses. Therefore, we proceeded to investigate the mechanisms by which dengue NS1 contributes to disease pathogenesis and if it is associated with altered IL-10 production. Serum IL-10 and dengue NS1 antigen levels were assessed serially in 36 adult Sri Lankan individuals with acute dengue infection. We found that the serum IL-10 levels correlated positively with dengue NS1 antigen levels (Spearman's r = 0·47, P < 0·0001), and NS1 also correlated with annexin V expression by T cells in acute dengue (Spearman's r = 0·63, P = 0·001). However, NS1 levels did not associate with the functionality of T cell responses or with expression of co-stimulatory molecules. Therefore, we further assessed the effect of dengue NS1 on monocytes and T cells by co-culturing primary monocytes and peripheral blood mononuclear cells (PBMC), with varying concentrations of NS1 for up to 96 h. Monocytes co-cultured with NS1 produced high levels of IL-10, with the highest levels seen at 24 h, and then declined gradually. Therefore, our data show that dengue NS1 appears to contribute to pathogenesis of dengue infection by inducing IL-10 production by monocytes.

Pediatric ischemic stroke due to dengue vasculitis

BACKGROUND

Dengue infection is an important arboviral infection in southeast Asia, especially in India. Neurological manifestations of dengue are increasingly recognized.

METHODS

We report an ischemic stroke due to dengue vasculitis in an 8-year-old child.

PATIENT

We present a girl with a short febrile illness followed by episodic severe headache, with gradually progressive hemiparesis and visual impairment. Her brain magnetic resonance imaging revealed multiple infarctions in the anterior and posterior circulation. The magnetic resonance angiogram revealed irregular narrowing of bilateral middle cerebral arteries, right anterior cerebral artery, left posterior cerebral, and bilateral vertebral arteries suggestive of vasculitis. Her dengue serology was strongly positive for immunoglobulin M with 68.9 panbio units. The rest of the evaluation for pediatric stroke was unremarkable. She was treated with intravenous followed by oral corticosteroids and recovered totally with resolution of vasculitis on magnetic resonance angiogram over the next 3 months.

CONCLUSION

This child illustrates possible immune-mediated vasculitis caused by dengue infection which is rather a rare presentation in a child who subsequently recovered well. One should consider dengue in childhood strokes in endemic regions.

Latest developments and future directions in dengue vaccines

Dengue is a mosquito-borne disease which is currently an expanding global health problem. The disease is caused by four closely related viruses, the dengue virus. There are no specific dengue therapeutics and prevention is currently limited to vector control measures. Development of an effective tetravalent dengue vaccine would therefore represent a major advance in the control of the disease and is considered a high public health priority. While a licensed dengue vaccine is not yet available, the scope and intensity of dengue vaccine development has increased dramatically in the last decade. The uniqueness of the dengue viruses and the spectrum of disease resulting from infection have made dengue vaccine development difficult. Several vaccine candidates are currently being evaluated in clinical studies. The candidate currently at the most advanced clinical development stage, a live-attenuated tetravalent vaccine based on chimeric yellow fever dengue virus, has progressed to phase III efficacy studies. Several other live-attenuated vaccines, as well as subunit, DNA and purified inactivated vaccine candidates, are at earlier stages of clinical development. Additional technological approaches, such as virus-vectored and virus-like particle-based vaccines, are under evaluation in preclinical studies.

Dengue specific immunoglobulins M, A, and E in primary and secondary dengue 4 infected Salvadorian children

El Salvador is a Central American country that has been affected by several dengue outbreaks. This study investigated the levels of IgM, IgA, and IgE anti-dengue antibodies in serum samples from children in El Salvador, with a clinical and serological diagnosis of dengue infection during the dengue 4 outbreak in 2002-2003. Seventy one serum samples were tested by ELISA and cases were classified in three groups: 13 primary dengue fever (PDF), 21 secondary dengue fever (SDF), and 37 secondary dengue hemorrhagic fever (SDHF). Also, the specificity of anti-dengue IgM for the different serotypes was tested. No significant differences in the IgM response were found between PDF and SDF, but these were detected between PDF and SDHF (P = 0.0053) and between SDF and SDHF (P = 0.0003). The IgA and IgE values showed a statistically significant difference between primary and secondary groups. The highest positivity percentage of IgA was between 95% (SDF) and 100% (SDHF) towards day 7 of onset of fever. All secondary cases were positive for IgE antibodies. The specificity of IgM was determined for DENV-4 virus in primary and secondary DF groups. This is the first study on dengue cases in Salvadorian children related to the immune response of different immunoglobulins to the type of infection and the clinical picture. Further prospective studies are needed to define if the pattern of immunoglobulins can determine early dengue infection and/or severity.

Spontaneous central vein thrombosis in a patient with activated protein C resistance and dengue infection: An association or causation?

Spontaneous central vein thrombosis is a rare and potentially fatal condition in critical care setting. Activated protein C resistance due to homozygous factor V Leiden mutation is an exceptional cause of central venous thrombosis. We recently treated a healthy female student who presented with acute febrile illness, septic shock, and encephalopathy. Neck ultrasonography (USG) prior to an attempt of right internal jugular vein (IJV) cannulation revealed non compressibility of the vein along with absence of venous blood flow. Right IJV and subclavian vein thrombus was confirmed subsequently in USG Doppler by radiologist. Radiological evidence of distal pulmonary artery embolism in pulmonary angiography was also evident. Further investigations demonstrated homozygous Factor V Leiden mutation and activated factor C resistance and Dengue IgM positivity in our patient. Intravenous heparin followed by oral vitamin K anticoagulants (OVKA) aided in her recovery. Spontaneous intravascular thrombosis with activated protein C resistance and the relationship of acute Dengue infection were explored in our report.

Seroprevalence and trend of dengue cases admitted to a government hospital, delhi - 5-year study (2006-2010): a look into the age shift

BACKGROUND

Diagnosis of dengue infection is easily and best accomplished by demonstration of specific IgM antibodies in blood. We analyzed retrospectively the dengue IgM seropositivity available for samples obtained over a period of 5 years (2006-2010) from patients with suspected dengue fever (DF)-like illness to investigate whether there was an overall increase in the dengue IgM prevalence over this period.

METHODS

Blood samples were collected from patients with DF-like febrile illnesses attending the Pediatric, Medicine, and Fever clinics of a Government hospital, Delhi. A total of 8138 individuals (suspected dengue cases) obtained over 5 years were tested for dengue specific IgM antibodies. Year wise, month wise, and age wise data on geographic distribution and clinical manifestations were analyzed.

RESULTS

Of the 8138 samples, 1600 (19.66%) were positive for dengue specific IgM. The year 2006 had the highest number of reported cases, 761 (46.23%). In our study, the age group most commonly affected of all 5 years was 11-20 years. Out of the total 1600 cases admitted to the hospital between 2006 and 2010, 279 (58.9%) had DF, 178 (37.6%) had dengue hemorrhagic fever, and 16 (3.38%) had dengue shock syndrome. We found a high burden of dengue in young children and late adolescents in both rural and urban communities at a magnitude greater than previously described.

INTERPRETATION AND CONCLUSION

We observed an increase in the dengue positive cases every alternate year, thereby indicating a possible role of herd immunity in northern India. We did not find a steady increase in the number of cases over 5 years. We found an increase in the number of positive cases in children and young adolescents.