Dengue Hemorrhagic Fever Shock Syndrome Research Articles

In-silico Characterization of Target Protein in Dengue Infection

Infection of humans with the virus is primarily mediated by the Aedes mosquito. The virus grows in the mosquito gut and migrates to aq 1 the salivary glands.. Dengue virus (DENV), which includes four serotypes (DENV1–4), is transmitted to humans by Aedes mosquitos and is the etiological agent of dengue fever and dengue hemorrhagic fever. DENV causes an estimated 50–100 million cases of dengue fever, 500,000 cases of severe dengue (dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS)), and more than 20,000 deaths each year in tropical and subtropical regions, representing a considerable public health threat in over 100 countries worldwide. However, there are still no specific antiviral drugs or licensed vaccines against DENV infection. Dengue virus primarily propagates in skin dendritic cells, and subsequently virus proliferation is thought to occur in target cells such as those of the monocyte/macrophage lineage. Second, carbohydrate binding proteins, termed lectins, expressed on dendritic cells (DCs) and macrophages under the human skin are involved in initial contact of DENV introduced by mosquito bite. Among these lectins, dendritic cell-specific intercellular adhesion molecule-3-grabbing non integrin (DCSIGN) has been best characterized in virus-DC interaction.

Clinical characteristic of dengue fever and dengue hemorrhagic fever among patients at Sanglah Hospital, Denpasar, Bali

Background: Mosquito-borne diseases are one of the most significant public health risks globally, and dengue fever seems to be one of the most important arboviral diseases in humans. In humans, dengue viruses are the supreme agents that cause dengue fever (DF) and dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). Following that, the virus's presence, sufficient numbers of susceptible populations, and mosquito vectors are required to transmit dengue infection. This study aimed to identify the clinical characteristics of dengue fever and dengue hemorrhagic fever among patients at Sanglah Hospital, Denpasar, BaliMethod: The study is a descriptive retrospective study design. The data was collected from the medical records of patients diagnosed with dengue and dengue hemorrhagic fever in Sanglah Hospital, Denpasar, Bali, from June 2015- June 2016. We took 50 patients according to sample size calculation by randomized sampling technic. Data were analyzed descriptively.Result: The study found the age range from 5 to 53 years old. The mean age for DF and DHF were 11 and 31, respectively. Secondly, the proportion of gender in this research was male by 21 (42%) and 29 (58%) female. Further to this, Denpasar showed the maximum number of cases between all the nine regencies. Both DF and DHF cases recorded the highest total cases in April 2016.Conclusion: Expected clinical characteristics prior knowledge and prognosticators of DF and DHF development will be able to provide data to detect persons who are higher risk category and provide adequate time to clinicians to lessen dengue related morbidity and mortality

Double-faced implication of CD4+ Foxp3+ regulatory Tcells expanded by acute dengue infection via TLR2/MyD88 pathway.

Dengue infection causes dengue fever (DF) and dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). CD4+ Foxp3+ Tregs are expanded in patients during dengue infection, and appear to be associated with clinical severity. However, molecular pathways involved in Treg proliferation and the reason for their insufficient control of severe diseases are poorly understood. Here, dengue infection induced the proliferation of functional CD4+ Foxp3+ Tregs via TLR2/MyD88 pathway. Surface TLR2 on Tregs was responsible for their proliferation, and dengue-expanded Tregs subverted in vivo differentiation of effector CD8+ Tcells. An additional interesting finding was that dengue-infected hosts displayed changed levels of susceptibility to other diseases in TLR2-dependent manner. This change included enhanced susceptibility to tumors and bacterial infection, but highly enhanced resistance to viral infection. Further, the transfer of dengue-proliferated Tregs protected the recipients from dengue-induced DHF/DSS and LPS-induced sepsis. In contrast, dengue-infected hosts were more susceptible to sepsis, an effect attributable to early TLR2-dependent production of proinflammatory cytokines. These facts may explain the reason why in some patients, dengue-proliferated Tregs is insufficient to control DF and DHF/DSS. Also, our observations lead to new insights into Treg responses activated by dengue infection in a TLR2-dependent manner, which could differentially act on subsequent exposure to other disease-producing situations.

The Reliability of C-Reactive Protein Levels in Predicting Dengue Severity: A Systematic Review

Background Clinical manifestations of dengue vary from mild febrile illnesses to shock and organ failure. However, severe symptoms may not be clinically evident immediately, making it difficult for early detection of patients at risk for poor outcomes. Several biomarkers, particularly C-reactive protein (CRP), were revealed to be highly predictive of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). This systematic review aims to determine a relationship between CRP levels and the probability of developing DHF/DSS. Methods Multiple electronic databases were searched for English literature from January 2007 to August 2017. Four reviewers independently extracted data from eligible studies using the standardized critical appraisal tool from JBI-MAStARI. Articles that scored six and above were included. Results Three cohort and two cross-sectional studies were reviewed. Sample sizes ranged from 70 to 235 participants. The cohort studies measured CRP levels at point of diagnosis, but were re-measured at different time points in the subjects’ admission. However, regardless of the time difference, they all showed that increased CRP levels exhibited a trend towards development of DSS/DHF. The studies also identified a possible “golden period” for measuring CRP levels that can accurately predict development of DHF/DSS. The cross-sectional studies also saw a similar trend, but have measured this in median values of the CRP levels. Conclusion This systematic review showed that increased CRP levels appeared to have a trend towards a higher probability of developing DHF/DSS. A larger population and more studies are needed to further establish a statistically significant relationship.

Genetic risk for dengue hemorrhagic fever and dengue fever in multiple ancestries

BackgroundGenetic risk factors for dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) and dengue fever (DF) are limited, in particular there are sparse data on genetic risk across diverse populations.MethodsWe conducted a genome-wide association study (GWAS) in a derivation and validation sample of 7, 460 participants of Latin American, South Asian, and South East Asian ancestries. We then developed a weighted polygenic risk score (PRS) for each participant in each of the validation cohorts of the three ancestries to predict the risk of DHF/DSS compared to DF, DHF/DSS compared to controls, and, DF compared to controls.FindingsThe risk of DHF/DSS was significantly increased, odds ratio [OR] 1.84 (95%CI 1.47 to 2.31) (195 SNPs), compared to DF, fourth PRS quartile versus first quartile, in the validation cohort. The risk of DHF/DSS compared to controls was increased (OR=3.94; 95% CI 2.84 to 5.45) (278 SNPs), as was the risk of DF compared to controls (OR=1.97; 95%CI 1.63 to 2.39) (251 SNPs). Risk increased in a dose-dependent manner with increase in quartiles of PRS across comparisons. Significant associations persisted for PRS built within ancestries and applied to the same or different ancestries as well as for PRS built for one outcome (DHF/DSS or DF) and applied to the other.InterpretationThere is a strong genetic effect that predisposes to risk of DHF/DSS and DF. The genetic risk for DHF/DSS is higher than that for DF when compared to controls, and this effect persists across multiple ancestries.

Molecular Signatures of Dengue Virus-Specific IL-10/IFN-γ Co-producing CD4 T Cells and Their Association with Dengue Disease

SUMMARYDengue virus (DENV) can cause diseases ranging from dengue fever (DF) to more severe dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). Whether antiviral T cells contribute to the protection against or pathogenesis of severe disease is not well defined. Here, we identified antigen-specific IL-10+IFN-γ+ double-positive (DP) CD4 T cells during acute DENV infection. While the transcriptomic signatures of DP cells partially overlapped with those of cytotoxic and type 1 regulatory CD4 T cells, the majority of them were non-cytotoxic/Tr1 and included IL21, IL22, CD109, and CCR1. Although we observed a higher frequency of DP cells in DHF, the transcriptomic profile of DP cells was similar in DF and DHF, suggesting that DHF is not associated with the altered phenotypic or functional attributes of DP cells. Overall, this study revealed a DENV-specific DP cell subset in patients with acute dengue disease and argues against altered DP cells as a determinant of DHF.

Molecular Signatures of Dengue Virus-Specific IL-10/IFN-γ Co-Producing CD4 T Cells and Their Association with Severe Dengue Disease

Dengue virus (DENV) can cause diseases ranging from self-limiting dengue fever (DF) to more severe dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). Whether DENV-specific T cells contribute to the protection against or pathogenesis of severe dengue disease is not well defined. In this study, we identified a novel IL-10+IFN-Υ+ double positive (DP) CD4 T cell subset that predominated the antigen-specific CD4 T cell response during acute DENV infection. While some of the transcriptomic and proteomic signatures of DP cells marginally overlapped with previously identified markers of cytotoxic CD4 T cells and type 1 regulatory T (Tr1)-like cell, the vast majority of the genes differentially expressed in DP cells were novel and included genes such as IL21, IL22, CD109, and CCR1. Although we observed higher frequencies of DENV-specific DP cells in DHF patients than in DF patients, their transcriptomic profile was similar in these two groups of patients, suggesting that dengue disease severity is not associated with altered phenotypic or functional attributes of this novel CD4 T cell subset. Overall, our in-depth transcriptomic, phenotypic, and functional analyses revealed a novel DENV-specific DP cell subset in patients with acute dengue disease and argue against altered CD4 T cell response as a determinant of disease severity.

Dual-Faced Implication of CD4 <sup>+</sup>Foxp3 <sup>+</sup> Regulatory T Cells Expanded by Acute Dengue Infection via TLR2/MyD88 Pathway

Background: Dengue infection causes dengue fever (DF) and fatal dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). CD4+Foxp3+ Tregs are expanded in human patients during dengue infection, and appear to be closely associated with clinical severity. However, the molecular pathways involved in Treg proliferation and the reason for their insufficient control of severe clinical disease in dengue infection are poorly understood. Methods: We investigated Treg expansion and their role in DF and DHF/DSS with elaborated immunological analysis using several genetically engineered mouse strains. Results: Here we found that dengue infection induced the proliferation of fully functional CD4+Foxp3+ Tregs via TLR2/MyD88 pathway. Also, surface TLR2 on Tregs was responsible for their proliferation, and dengue-expanded Tregs subverted in vivo differentiation of effector CD8+ T cells. A more interesting finding was that dengue-infected hosts displayed changed levels of susceptibility to other diseases in a TLR2-dependent manner. This change included enhanced susceptibility to tumors and bacterial infection, but highly enhanced resistance to viral infection. Further, transfer of dengue-proliferated Tregs protected the recipients from DF and DHF/DSS caused by dengue infection and LPS-induced sepsis. In contrast, hosts that developed sepsis were more susceptible to dengue infection, an effect attributed to early TLR2-dependent production of proinflammatory cytokines. Interpretation: These facts may explain the reason why in some patients, dengue-proliferated Tregs is insufficient to control DF and DHF/DSS. Our observations lead to new insights into Treg responses activated by dengue infection in a TLR2-dependent manner, which could differentially act on subsequent exposure to other disease-producing situations. Funding: National Research Foundation of Korea (2018R1A2B2001873, 2019R1A6A1A03033084). Declaration of Interest: The authors declare no competing financial interests. Ethical Approval: All animal experiments described in the present study were conducted at Chonbuk National University according to the guidelines set by the Institutional Animal Care and Use Committee (IACUC) of Chonbuk National University, and were pre-approved by the Ethics Committee for Animal Experiments of Chonbuk National University (approval number: 2013-0028). The animal research protocol used in this study followed the guidelines set by the nationally recognized Korea Association for Laboratory Animal Sciences (KALAS). All experimental protocols requiring biosafety were approved by the Institutional. Biosafety Committee (IBC) of Chonbuk National University.

Clinical Characteristic and Risk Factors of Acute Kidney Injury among Dengue Viral Infections in Adults: A Retrospective Analysis.

Dengue is a growing public health problem in India, and acute kidney injury (AKI) is one of the least studied complications of dengue virus infection (DVI). This study was conducted to investigate the incidence, clinical characteristics, and risk factors for AKI in DVI. This was a retrospective study of patients with confirmed DVI presenting as dengue fever (DF) or dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) at our center over a period of 2 years. A total of 620 subjects fulfilling inclusion criteria were studied. Patients were divided into two cohorts (90 patients with AKI and 530 patients without AKI) to determine independent predictors of AKI. Among 620 patients, 454 (73.22%) had classical DF, 141 (22.74%) patients had DHF, and 25 (4.03%) patients had DSS. AKI was present in 90 (16.36%) patients; approximately one-third (31, 34.45%) had AKIN stage 1, 33 (36.66%) patients had AKIN stage 2, and 26 (28.88%) had AKIN stage 3. Among those with AKI, 14 patients expired and all had DHF/DSS. On multivariate logistic regression, AKI was associated with male gender [odds ratio (OR): 2.9], DHF (OR: 7.9), rhabdomyolysis (OR: 8.2), multiple-organ dysfunction (OR: 18.2), hypertension (OR: 0.7), diabetes mellitus (OR: 4.8), delayed hospitalization (OR: 2.2), and use of nephrotoxic drugs (OR: 2.86). In all, 320 patients (51.61%) had hospital stay >3 days. We found that AKI was an independent predictor for longer duration of hospital stay (OR: 7.2, 95% confidence interval: 4.8–10.7). AKI in DVI is associated with significant morbidity, mortality and longer hospital stay.

Serum fatty acids and progression from dengue fever to dengue haemorrhagic fever/dengue shock syndrome

PUFA might modulate inflammatory responses involved in the development of severe dengue. We aimed to examine whether serum PUFA concentrations in patients diagnosed with dengue fever (DF) were related to the risk of progression to dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS). A secondary aim was to assess correlations between fatty acids (FA) and inflammatory biomarkers in patients with DF. We conducted a prospective case-control study nested within a cohort of patients who were diagnosed with DF and followed during the acute episode. We compared the distribution of individual FA (% of total FA) at onset of fever between 109 cases who progressed to DHF/DSS and 235 DF non-progressing controls using unconditional logistic regression. We estimated correlations between baseline FA and cytokine concentrations and compared FA concentrations between the acute episode and >1 year post-convalescence in a subgroup. DHA was positively related to progression to DHF/DSS (multivariable adjusted OR (AOR) for DHA in quintile 5 v. 1=5·34, 95 % CI 2·03, 14·1; P trend=0·007). Dihomo-γ-linolenic acid (DGLA) was inversely associated with progression (AOR for quintile 5 v. 1=0·30, 95 % CI 0·13, 0·69; P trend=0·007). Pentadecanoic acid concentrations were inversely related to DHF/DSS. Correlations of PUFA with cytokines at baseline were low. PUFA were lower during the acute episode than in a disease-free period. In conclusion, serum DHA in patients with DF predicts higher odds of progression to DHF/DSS whereas DGLA and pentadecanoic acid predict lower odds.

Synergism between the tyrosine kinase inhibitor sunitinib and Anti-TNF antibody protects against lethal dengue infection

Dengue virus (DENV) currently circulates in more than 100 countries and causes an estimated 390 million infections per year. While most cases manifest as a self-resolving fever, ∼1.5% of infections develop into a more severe dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS), which causes ∼20,000 deaths annually. The underlying pathological feature of DHF/DSS, also known as Severe Dengue, is an acute increase in vascular permeability leading to hypovolemia and shock. Angiogenic factors and cytokines, such as vascular endothelial growth factor (VEGF) and tumor necrosis factor (TNF), have been implicated in the increased vascular permeability, suggesting a potential therapeutic strategy for Severe Dengue. Here, we employed a mouse model of antibody-dependent enhancement of DENV infection, which recapitulates the fatal capillary leakage and shock of human Severe Dengue, to investigate the effects of approved VEGF- and TNF-targeting drugs. DENV infection caused a significant increase in serum VEGF levels within 2 days and resulted in ∼80% mortality within 8 days of infection. Treatment of mice with sunitinib, a VEGF receptor tyrosine kinase inhibitor, once (day 2) or twice (days 1 and 2) post-infection reduced mortality by 50–80% compared with untreated mice. Notably, sunitinib treatment decreased serum TNF levels, white blood cell counts, and hematocrit levels relative to untreated mice, but had only marginal effects on tissue viral burden. Combination therapy with anti-TNF antibody and sunitinib significantly reduced vascular leakage and synergized to provide superior protection from lethal DENV infection compared with either agent alone. These data suggest that a two-pronged anti-angiogenic and anti-inflammatory approach may be useful for the rapid treatment of DHF/DSS.

Let-7e inhibits TNF-α expression by targeting the methyl transferase EZH2 in DENV2-infected THP-1 cells.

Tumor necrosis factor α (TNFα), an important inflammatory cytokine, is associated with dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS), a severe pathological manifestation of dengue virus (DENV) infection. However, the regulatory mechanism of microRNA on TNFα is currently unknown. Our study showed that the TNFα expression increased immediately and then later decreased, while a marked increase for the miRNA let-7e was detected in dengue virus type 2 (DENV2)-infected peripheral blood mononuclear cells (PBMCs). From this study, we found that let-7e was able to inhibit TNFα expression, but bioinformatics analysis showed that the enhancer of zeste homolog 2 (EZH2) was the potential direct target of let-7e instead of TNFα. EZH2 methyl transferase can produce H3K27me3 and has a negative regulatory role. Using a dual-luciferase reporter assay and Western blotting, we confirmed that EZH2 was a direct target of let-7e and found that siEZH2 could inhibit TNFα expression. In the further study of the regulatory mechanism of EZH2 on TNFα expression, we showed that siEZH2 promoted EZH1 and H3K4me3 expression and inhibited H3K27me3 expression. More importantly, we revealed that siEZH2 down-regulated NF-κB p65 within the nucleus. These findings indicate that the let-7e/EZH2/H3K27me3/NF-κB p65 pathway is a novel regulatory axis of TNFα expression. In addition, we determined the protein differences between siEZH2 and siEZH2-NC by iTRAQ and found a number of proteins that might be associated with TNFα.

Simultaneous detection and serotyping of dengue infection using single tube multiplex CDC Dengue Real-Time RT-PCR from India.

Four antigenically different dengue virus serotypes (DENV-1, DENV-2, DENV-3 and DENV-4) are known to cause infections in humans. Some of these are known to cause more severe disease than the others. Chances for developing Dengue hemorrhagic fever-dengue shock syndrome (DHF-DSS) increases significantly with history of previous infection with one of the four serotypes. Therefore, early diagnosis, serotyping and providing early warning of dengue fever epidemics to concerned authorities becomes very important for better patient outcome and to curb the rapid spread in the community. During the 2014 outbreak, a total of 100 samples from suspected cases of dengue were collected. NS1 antigen based rapid test was used for serological diagnosis. Dengue complex one step reverse transcription-polymerase chain reaction was performed to look for presence of viral RNA. Single tube multiplex RT-PCR was also performed to look for infecting serotype. CDC Dengue Multiplex Real Time PCR assay was performed for rapid diagnosis and simultaneous serotyping of the dengue virus. Out of the 100 samples screened, 69 were found to be positive by NS1Ag Rapid test. 34 samples were found positive by dengue consensus RT-PCR assay. 22 samples were found to be positive by single tube Dengue multiplex RT-PCR assay. Serotype DEN-2 was present in maximum numbers followed by DEN-3. 44 samples were found positive by DENV CDC Multiplex Real time PCR assay. DEN-2 was found in maximum numbers followed by DEN-1. Dengue remains to be an important health problem in India and across the globe. Few serotypes of dengue are more dangerous than the others. Rapid diagnosis and serotyping remains the key for better patient management and prevention of disease spreading in the community. Highly sensitive, specific and rapid CDC real time RT-PCR assay was found to be most promising tool among all available molecular diagnostic methods. This will serve a rapid and reliable simultaneous dengue virus detection as well serotyping assay in near future for rapid identification of dengue suspected sample screening.

Vitamin D serostatus and dengue fever progression to dengue hemorrhagic fever/dengue shock syndrome.

Vitamin D could modulate pathways leading to dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). We examined the associations of serum total 25-hydroxy vitamin D [25(OH)D] and vitamin D binding protein (VDBP) concentrations in patients with uncomplicated dengue fever (DF) with risk of progression to DHF/DSS. In a case-control study nested in a cohort of DF patients who were followed during the acute episode in Bucaramanga, Colombia, we compared 25(OH)D and VDBP at onset of fever between 110 cases who progressed to DHF/DSS and 235 DF controls who did not progress. 25(OH)D concentrations were also compared between the acute sample and a sample collected >1 year post-convalescence in a subgroup. Compared with 25(OH)D ⩾75 nmol/l, adjusted odds ratios (95% CI) for progression were 0·44 (0·22-0·88) and 0·13 (0·02-1·05) for 50 to 75 nmol/l (vitamin D insufficiency) and <50 nmol/l (vitamin D deficiency), respectively (P, trend = 0·003). Mean 25(OH)D concentrations were much lower post-convalescence compared with the acute episode, regardless of case status. Compared with controls, mean VDBP was non-significantly lower in cases. We conclude that low serum 25(OH)D concentrations in DF patients predict decreased odds of progression to DHF/DSS.

Anti-Idiotypic Antibodies Specific to prM Monoantibody Prevent Antibody Dependent Enhancement of Dengue Virus Infection.

Dengue virus (DENV) co-circulates as four serotypes (DENV1-4). Primary infection only leads to self-limited dengue fever. But secondary infection with another serotype carries a higher risk of increased disease severity, causing life-threatening dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). Serotype cross-reactive antibodies facilitate DENV infection in Fc-receptor-bearing cells by promoting virus entry via Fcγ receptors (FcγR), a process known as antibody dependent enhancement (ADE). Most studies suggested that enhancing antibodies were mainly specific to the structural premembrane protein (prM) of DENV. However, there is still no effective drugs or vaccines to prevent ADE. In this study, we firstly confirmed that both DENV-2 infected human sera (anti-DENV-2) and DENV-2 prM monoclonal antibody (prM mAb) could significantly enhance DENV-1 infection in K562 cells. Then we developed anti-idiotypic antibodies (prM-AIDs) specific to prM mAb by immunizing of Balb/c mice. Results showed that these polyclonal antibodies can dramatically reduce ADE phenomenon of DENV-1 infection in K562 cells. To further confirm the anti-ADE effect of prM-AIDs in vivo, interferon-α and γ receptor-deficient mice (AG6) were used as the mouse model for DENV infection. We found that administration of DENV-2 prM mAb indeed caused a higher DENV-1 titer as well as interleukin-10 (IL-10) and alaninea minotransferase (ALT) in mice infected with DENV-1, similar to clinical ADE symptoms. But when we supplemented prM-AIDs to DENV-1 challenged AG6 mice, the viral titer, IL-10 and ALT were obviously decreased to the negative control level. Of note, the number of platelets in peripheral blood of prM-AIDs group were significantly increased at day 3 post infection with DENV-1 compared that of prM-mAb group. These results confirmed that our prM-AIDs could prevent ADE not only in vitro but also in vivo, suggested that anti-idiotypic antibodies might be a new choice to be considered to treat DENV infection.

Acute Renal Failure in Dengue Infection.

Acute Renal Failure (RF) is a rare but well recognized complication of Dengue Infection (DI). There has been paucity of published data regarding renal involvement in DI. The aim of the present study was to elucidate different clinical presentations, disease outcomes of DI. To study the frequency, severity and predictors of RF in DI. Patients diagnosed either as Dengue Fever (DF) or Dengue Haemorrhagic Fever/Dengue Shock Syndrome (DHF/DSS) respectively were enrolled for this study. The diagnostic criteria for DI were febrile illness associated with one of the following: 1) detection of dengue-specific IgM capture antibody or Non-Structural Protein1 (NS1) antigen; or 2) a four-fold or greater increase of dengue-specific IgG capture antibody by ELISA and haemoagglutination inhibition assay. Patients were diagnosed as having Acute RF, if serum creatinine was >1.2 mg/dl or who showed improvement by 50% in serum creatinine from the initial value. It is an observational study of medical charts, data of age, gender, and medical history of any underlying diseases in association with the severity of DI of each patient recorded. All of the laboratory results were collected. Parameters that influenced the clinical presentations and outcomes for development of classical DF or DHF/DSS in patients with or without RF were analysed and compared. Descriptive and inferential statistical analysis was carried. The Statistical software namely SAS 9.2, SPSS 15.0, Stata 10.1, Med Calc 9.0.1, Systat 12.0 and R environment ver.2.11.1 were used. Most common symptoms were fever followed by headache and pain in abdomen. Among the patients with RF, all patients had recovery. The patients with DHF/DSS were more susceptible to develop renal failure compared to DF group. There were statistically significant higher frequencies of renal failure, haemoconcentration, thrombocytopenia, low serum cholesterol. Patients in the RF group also had significantly higher percentages of shock, haemoconcentration, thrombocytopenia, raised AST and low serum cholesterol compared to non-RF group. There were no mortality and none of them had to receive renal replacement therapy during hospitalization. Patients with DHF/DSS were more susceptible to develop renal failure compared to DF group. Patients in the RF group had higher percentages of shock, haemoconcentration, thrombocytopenia, raised AST and low serum cholesterol.

Synergistic Effect of TNF-α and Dengue Virus Infection on Adhesion Molecule Reorganization in Human Endothelial Cells.

Dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) is a severe pathological manifestation of dengue virus (DENV) infection. Enhanced production of cytokines in dengue patients is proposed to induce endothelial barrier instability resulting in increased vascular leakage. Tumor necrosis factor (TNF)-α is an inflammatory cytokine that activates endothelial cells and enhances vascular permeability and plasma leakage in DHF/DSS. The present study investigated the in vitro effect of TNF-α and DENV infection on the expression of adherence junction proteins, tight junction proteins, and membrane integrity of human endothelial cell lines. Immunofluorescence staining and western blot analysis demonstrated platelet endothelial cell adhesion molecule-1 (PECAM-1) reorganization and decreased levels of the tight junction protein occludin in human endothelial cells treated with TNF-α and DENV, compared to mock, DENV, or TNF-α-treated cells. Permeability assessed by FITC-dextran as a transport molecule was increased and correlated with the unusual reorganization of PECAM-1. The altered distribution of PECAM-1 and low occludin protein levels in human endothelial cells treated with TNF-α and DENV correlated with increased permeability. In conclusion, the synergistic effect of TNF-α and DENV induced permeability changes in endothelial cells. These results contribute to the understanding of the mechanisms underlying enhanced vascular permeability in DENV infection.

Pathogenesis of Dengue: Dawn of a New Era.

Dengue virus (DENV) infections of humans were long thought to be self-limited and of low mortality. Beginning in the 1950s, at the time when four different DENVs were discovered, a lethal variant of dengue emerged. Dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) initially observed in Southeast Asia now has spread throughout the world. Two risk factors for DHF/DSS are well-established: severe disease occurs during a second heterotypic DENV infection or during a first DENV infection in infants born to dengue-immune mothers. A large number of hypotheses have been proposed to explain severe dengue disease. As discussed, few of them attempt to explain why severe disease occurs under the two different immunological settings. New experimental evidence has demonstrated that DENV non-structural protein 1 (NS1) is toll-receptor 4 agonist that stimulates primary human myeloid cells to produce the same cytokines observed during the course of severe dengue disease. In addition, NS1 directly damages endothelial cells. These observations have been repeated and extended to an in vivo mouse model. The well-established phenomenon, antibody-dependent enhancement of DENV infection in Fc-receptor-bearing cells, should similarly enhance the production of DENV NS1 in humans, providing a unitary mechanism for severe disease in both immunological settings

Antibody avidity following secondary dengue virus type 2 infection across a range of disease severity

BackgroundThe four dengue virus serotypes (DENV1-4) are responsible for the most prevalent mosquito-borne viral illness in humans. DENV causes a spectrum of disease from self-limiting dengue fever (DF) to severe, life-threatening dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). Antibodies from one infection can contribute to either protection or increased disease severity in a subsequent infection with a distinct DENV serotype. The effectiveness of the antibody response is modulated by both the affinity and avidity of the antibody/antigen interaction. ObjectivesWe investigated how antibody avidity developed over time following secondary DENV2 infection across different disease severities. Study designWe analyzed sera from 42 secondary DENV2-infected subjects (DF, n=15; DHF, n=16; DSS, n=11) from a pediatric hospital-based dengue study in Nicaragua. IgG avidity against DENV2 virions was measured in samples collected during acute and convalescent phases as well as 3, 6, and 18 months post-illness using a urea enzyme-linked immunosorbent assay. ResultsThe data show a significant increase in avidity from acute to convalescent phase followed by a decrease from convalescent phase to 3 months post-symptom onset, then a plateau. Linear regression analysis comparing antibody avidity between disease severity groups over time indicate that individuals with more severe disease (DHF/DSS) experienced greater decay in antibody avidity over time compared to less severe disease (DF), and ROC curve analysis showed that at 18 months post-illness, lower avidity was associated with previously having experienced more severe disease. ConclusionsThese data suggest that increased dengue disease severity is associated with lower antibody avidity at later time-points post-illness.

Pathogenic roles of macrophage migration inhibitory factor during dengue virus infection.

Dengue virus (DENV) infection is the most common cause of viral hemorrhagic fever, which can lead to life-threatening dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). Hemorrhage and plasma leakage are two major hallmarks of DHF/DSS. Because the mechanisms causing these pathogenic changes are unclear, there is no effective therapy against DHF/DSS. In this review, we focus on the possible pathogenic effects of a pleiotropic cytokine, macrophage migration inhibitory factor (MIF), on the pathogenesis of DENV infection. MIF is a critical mediator of the host immune response and inflammation, and there is a correlation between the serum levels of MIF and disease severity in dengue patients. Furthermore, MIF knock-out mice exhibit less severe clinical disease and lethality. However, the role of MIF in the pathogenesis of DHF/DSS is not limited to immune cell recruitment. Recent evidence indicates that DENV infection induced MIF production and may contribute to vascular hyperpermeability and viral replication during DENV infection. The expression of both adhesion and coagulation molecules on MIF-stimulated monocytes and endothelial cells is also increased, which may contribute to inflammatory and anticoagulatory states during DHF/DSS. Therefore, blocking MIF production or its function may provide a solution for the treatment and prevention of DHF/DSS.