High Anti-Dengue Virus Activity of the OAS Gene Family Is Associated With Increased Severity of Dengue.

Dengue is a mosquito-borne viral disease that afflicts millions of individuals worldwide every year. Infection by any of the 4 dengue virus (DENV) serotypes can result in a spectrum of disease severity. We investigated the impact of variants of interferon-regulated innate immunity genes with a potent antiviral effect on the outcome of DENV infection. We compared the effect of OAS gene family variants on 2 DENV serotypes in cell culture. While both OAS1-p42 and p46 showed antiviral activity against DENV-2, only OAS1-p42 presented anti-DENV-1 activity. Conversely, whereas both OAS3_S381 and R381 variants were able to block DENV-1 infection, the anti-DENV-2 activity observed for OAS3_S381 was largely lost for the R381 variant. By means of an allelic association study of a cohort of 740 patients with dengue, we found a protective effect of OAS3_R381 against shock (odds ratio [OR], 0.37; P < .001). This effect was due to DENV-2 infections (OR, 0.13; P = .007) but was absent for DENV-1, in accordance with the serotype-dependent OAS3 activity found in the functional study. Severe dengue has long been associated with a cytokine storm of unclear origin. This work identifies an early innate immunity process that could lead to the immune overreaction observed in severe dengue and could be triggered by a specific host genotype-pathogen genotype interaction.

Hemostatic derangement in dengue hemorrhagic fever.

Dengue hemorrhagic fever (DHF) is a more severe manifestation of dengue virus infection. Patients with DHF exhibit abnormal hematological indices, including high hematocrit, low white blood cells, low neutrophils, high lymphocytes, increased atypical lymphocytes, low platelets, slightly prolonged activated partial thromboplastin time, prothrombin time, and thrombin time. Abnormal platelet functions manifest as impaired platelet aggregation to ADP, and concurrent increases in plasma thromboglobulin and platelet factor 4 levels are also seen. Variable reductions in the activities of coagulation factors including prothrombin, V, VII, VIII, IX, and X may be present. The plasma level of antithrombin is typically normal, but protein C and protein S are modestly reduced. Within the fibrinolytic system, slightly increased levels of tissue-plasminogen activator accompanied by slightly increased plasminogen activator inhibitor-1 and decreased thrombin activatable fibrinolysis inhibitor have been demonstrated. These derangements are prominent in patients with DHF grades III and IV, collectively known as dengue shock syndrome. Moreover, patients with excessive depletion of intravascular volume from plasma leakage and/or massive bleeding from endothelial dysfunction, thrombocytopenia, platelet dysfunction, and coagulopathy may exhibit shock, prolonged shock and repeated shock. DIC is also commonly found in these complicated patients. However, most patients recover spontaneously with normalization of abnormal laboratory profiles during the convalescent stage or within one to two weeks after defervescence.

Tumour necrosis factor gene polymorphism in dengue infection: association with risk of bleeding.

BACKGROUND: A single nucleotide polymorphism located at the promoter -308A of tumour necrosis factor-alpha (TNF-α) gene may affect transcription and increase cytokine production, leading to the severe manifestation of dengue virus infection. AIM: To study the association of the TNF-α -308A allele and the severity of patients with dengue infection. METHODS: 112 patients suspected of having dengue infection and 106 normal controls were enrolled in the study. Mean (SD) age was 10.4 (3.6) years. In all, 19 and 82 patients were diagnosed with dengue fever (DF) and dengue haemorrhagic fever (DHF), respectively, while 11 were diagnosed with other febrile illnesses (OFIs). They were tested for the polymorphisms at the promoter -308 position of the TNF-α gene and their TNF-α levels were measured. RESULTS: In the patients with dengue infection (14/202, 6.9%) with OFIs (1/22, 4.5%) and in normal controls (17/212, 8.0%), the frequency of the TNF-α -308A allele was not significantly different. Moreover, no statistically significant difference was found in patients with various clinical manifestations of dengue infection involving DF (5.3%, 2/38), DHF grade I (5.0%, 2/40), DHF grade II (9.5%, 4/42), DHF grade III (2.5%, 1/40) and DHF grade IV (11.9%, 5/42). However, patients with dengue infection and significant bleeding manifestations, apart from petechiae and ecchymosis, tended to have a higher frequency of the TNF-α -308A allele (11.8%, 9/76) than those without significant bleeding manifestations (5/126, 4.0%) (P = 0.056). The levels of TNF-α were additionally measured in 67 patients but the results failed to demonstrate a functional effect in the transcriptional rate of the TNF-α -308A allele. CONCLUSION: In patients with dengue infection there is an association between the TNF-α -308A allele and the risk of bleeding. The test may be used as one of the predictors of the severity of dengue infection.

Dengue infection in hematologic-oncologic pediatric patients: aggravation of anemia and bleeding risk.

We studied anemia and bleeding risk among hematologic-oncologic pediatric patients with dengue infection. A total of 907 patients suspected of having dengue infection were included in the study. They were categorized into 2 groups: 1) patients with confirmed dengue infection (n=843) and 2) patients with other febrile illnesses (n = 64). Both groups included patients with underlying hematologic-oncologic diseases (55 vs 14) and without underlying disease (788 vs 50). Patients with underlying diseases were divided into 3 subgroups by risk: Subgroup A, anemia risk, including patients with thalassemia and hemoglobinopathies (n = 39) and G6PD deficiency (n=6); Subgroup B, patients with bleeding risk, including hemophilia (n = 7), von Willebrand disease (n = 1) and thrombocytopenia (n = 4); and Subgroup C, patients with anemia and bleeding risk, including oncologic diseases (n =12). Acute hemolysis in Subgroup A started during the febrile stage and required packed red cell transfusions. Bleeding risk in Subgroup B started during the early febrile stage with vasculopathy and continued to the late febrile stage with thrombocytopenia. These patients required factor concentrate and platelet concentrate transfusions. Anemia and bleeding risk in Subgroup C was greater among patients undergoing chemotherapy than those who had discontinued treatment. The greater the length of time since discontinuation of treatment, the lower risk. The case-fatality rate among dengue infected patients with underlying disease (2/55 = 3.64%) was significantly higher than those without underlying disease 0.63% (5/788).

Cardiovascular change in children with dengue shock syndrome.

To determine the cardiovascular changes in children with dengue shock syndrome. Echocardiography was performed in 8 children (5 females) with dengue shock syndrome, median age 6.5, 4.2-13.7 yr and weight 34, 12-66 kg. All had massive bleeding with low initial hematocrit in most cases (median 31%), thrombocytopenia (median platelet 37,000/µL), and coagulopathy with massive pleural effusion. Seven (87.5%) developed acute renal failure and hepatic failure. All patients were in either compensate or decompensate shock with alteration of consciousness, tachycardia, poor tissue perfusion, and prolonged capillary refill (>4 s) with mean arterial pressure 65, 39-94 mm Hg. The cardiac dimension was normal to low normal except one had dilated left ventricle. Seven patients had normal left ventricular systolic function (5 with inotrope infusion). One patient had impaired systolic function even with inotrope. All had normal cardiac index (4.14, 3.51-6.37 L/min/m2) with increased heart rate (141.5, 110-160/min) but low stroke volume index (30.72, 25.37-42.49 mL/m2) and low systemic vascular resistance index (1,072, 223-2,880 dyne/sec/cm-5/m2). Decreased preload from bleeding and vascular leakage into the third space play an important role in shock in Dengue. However, decreased stroke volume and low systemic vascular resistance may be additional causes of shock.

Dengue nonstructural protein 1 antigen in the urine as a rapid and convenient diagnostic test during the febrile stage in patients with dengue infection.

A total of 136 matched serum and urine samples obtained from 55 patients with dengue infection and 30 other febrile illnesses were assayed for dengue nonstructural protein 1 (NS1) antigen. The urine NS1 ELISA was positive in patients with dengue fever (68.4%) and dengue hemorrhagic fever (63.9%), whereas the strip method showed a lower positive rate.

Evaluation of dengue nonstructural protein 1 antigen strip for the rapid diagnosis of patients with dengue infection.

Two hundred twenty samples obtained from 104 patients with dengue infection (n = 89) and other febrile illnesses (n = 15) were assayed for dengue nonstructural protein 1 (NS1) antigen by enzyme immunoassay and by an immunochromatography (lateral flow) test strip. The sensitivity and the specificity of dengue NS1 antigen strip were 98.9% and 90.6%, respectively.

Serum ferritin levels in children with dengue infection.

The purpose of this study was to evaluate the levels of ferritin, an acute-phase reactant, in predicting the risk of dengue hemorrhagic fever (DHF) in patients with dengue infection. One hundred seventy-seven Thai children (100 males, 77 females) 4-16 years old (median age 11 years) with DF (n = 44) and DHF (n = 133) were enrolled in the study. All patients had serologic confirmation of dengue infection. Each had a venous blood sample drawn daily during hospitalization and at the outpatient clinic 2-4 weeks after discharge from the hospital, to determine serum ferritin levels. The median serum ferritin levels (ng/ml) in children with DHF (Day 2, 974; Day 3, 624; Day 4, 1,136; Day 5, 1,912; Day 6, 2, 105; Day 7, 1,840; Day 8, 1,478 and Day 9, 1,144 of illness) were higher than those with DF (Day 2, 25.4; Day 3, 45.6; Day 4, 655; Day 5, 1,050; Day 6, 1,075; Day 7, 615; Day 8, 764 and Day 9, 600 of illness) with p-values of 0.013, 0.001 and 0.013 on Days 5, 6 and 7 of illness, respectively. A cutoff level of serum ferritin of 1,200 ng/ml was used to calculate sensitivity and specificity for DHF. The results reveal the sensitivities on Days 5, 6 and 7 of illness were 81.5, 84.4 and 89.9%, respectively, and the specificities were 42.4, 39.0 and 36.4%, respectively. High serum ferritin levels > or = 1,200 ng/ml may be a predictor of dengue hemorrhagic fever.

The use of dengue nonstructural protein 1 antigen for the early diagnosis during the febrile stage in patients with dengue infection.

BACKGROUND: To evaluate the use of dengue nonstructural protein 1 (NS1) antigen for the early diagnosis during the febrile stage in patients with dengue infection. METHODS: A total of 445 sera obtained from 165 patients [dengue fever (DF): 42, dengue hemorrhagic fever (DHF) grade I: 50, II: 63, III and IV: 10] and 8 other febrile illnesses 5-15 years of age, were assayed for the NS1 antigen, dengue-specific Ig M and Ig G antibodies. RESULTS: The positive rates of NS1 antigen among patients with either DF or DHF was 100% (7 of 7) on day 2, 92.3% (12 of 13) on day 3, 76.9% (40 of 52) on day 4, 56.5% (61 of 108) on day 5 of fever; and declined to 43.1% (59 of 137) on day 6 with defervescence and 29.8% (25 of 84) on day 7 (1 day after defervescence). The positive rates of patients with DF were higher than those with DHF but no statistically significant difference was found. However, patients with primary DHF infection had significantly higher positive rates than those with secondary DHF infection. The positive rates of Ig M antibodies were in reverse proportion to those of NS1 antigen. The additional Ig M antibody determination increased the positive rates to 90.4% (47 of 52) on day 4, 83.3% (90 of 108) on day 5 of fever; 95.6% (131 of 137) on day 6 with defervescence, and 88.1% (74 of 84) on day 7. CONCLUSIONS: Dengue NS1 antigen testing is suggested as a helpful tool for the early diagnosis of dengue infection after the onset of fever. The additional Ig M antibody determination increased the diagnostic rates.

A variant in the CD209 promoter is associated with severity of dengue disease.

Dengue fever and dengue hemorrhagic fever are mosquito-borne viral diseases. Dendritic cell-specific ICAM-3 grabbing nonintegrin (DC-SIGN1, encoded by CD209), an attachment receptor of dengue virus, is essential for productive infection of dendritic cells. Here, we report strong association between a promoter variant of CD209, DCSIGN1-336, and risk of dengue fever compared with dengue hemorrhagic fever or population controls. The G allele of the variant DCSIGN1-336 was associated with strong protection against dengue fever in three independent cohorts from Thailand, with a carrier frequency of 4.7% in individuals with dengue fever compared with 22.4% in individuals with dengue hemorrhagic fever (odds ratio for risk of dengue hemorrhagic fever versus dengue fever: 5.84, P = 1.4 x 10(-7)) and 19.5% in controls (odds ratio for protection: 4.90, P = 2 x 10(-6)). This variant affects an Sp1-like binding site and transcriptional activity in vitro. These results indicate that CD209 has a crucial role in dengue pathogenesis, which discriminates between severe dengue fever and dengue hemorrhagic fever. This may have consequences for therapeutic and preventive strategies.