Kanchana Tangnararatchakit

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 × 10−7) and 19.5% in controls (odds ratio for protection: 4.90, P = 2 × 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.

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.

Elevated Soluble Thrombomodulin in the Febrile Stage Related to Patients at Risk for Dengue Shock Syndrome

Background: Children with dengue hemorrhagic fever (DHF) are at risk to develop dengue shock syndrome (DSS) for which neither marker has been demonstrated. Objective: The study was designed to investigate the markers of vascular endothelial cell injuries and dysfunction that might be used as early predictors of the subsequent manifestation of DSS. Methods: The blood samples from 111 patients with dengue fever, DHF and other febrile illness (OFI) were collected daily from the day of admission until discharge and at convalescent stage. The sample from the day of defervescence was defined as day 0, 1 day before defervescence was defined as day –1 and so on. Also, 1 day after defervescence was defined as day +1 and so on. Results: Increased soluble thrombomodulin (sTM) was demonstrated in dengue-infected patients via an enzyme-linked immunosorbent assay. Patients with DSS (DHF grades III and IV) had higher concentrations of sTM than those with dengue fever, DHF grade I, II and OFIs from day –3 until day +2. Increased circulating endothelial cells were detected from day 0 until day +2 in DSS patients as compared with other groups. In addition, increased soluble vascular cell adhesion molecule-1, soluble intercellular adhesion molecule-1 and soluble E-selectin were also found in dengue virus-infected patients as compared with OFIs. Conclusion: Blood sTM may be useful as an early predictor of DSS in dengue infected patients in the febrile stage. However, a further evaluation in a large prospective series is needed.

Alteration of cytokines and chemokines during febrile episodes associated with endothelial cell damage and plasma leakage in dengue hemorrhagic fever.

Background: The leakage of plasma during febrile episodes in dengue-infected patients is a severe condition leading to dengue shock syndrome. Alteration of cytokines/chemokines is suspected to be a major cause of endothelial cell damage in these patients. The study was designed to demonstrate the alteration of cytokines and chemokines in dengue-infected patients during febrile episodes. Methods: The blood samples from 164 patients with dengue fever, dengue hemorrhagic fever and other febrile illnesses were collected daily from the day of hospitalization until discharge and also in the convalescent stage. The levels of cytokines/chemokines were determined using a sandwich chemiluminescent immunoassay, and the hematological parameters were examined by the ADVIA hematological analyzer. Results: Two patterns of cytokines/chemokines alteration were detected at different time points during the febrile episode. The increased factors included interleukin (IL)-4, IL-6, IL-8, IL-10, tumor necrosis factor-&agr;, interferon-&ggr; and monocyte chemoattractant protein-1 whereas IL-1&bgr;, IL-2, vascular endothelial growth factor and epidermal growth factor were decreased. Several cytokines were correlated with disease severity especially in dengue hemorrhagic fever/dengue shock syndrome patients. Conclusions: The alteration in the cytokine/chemokine kinetics during a febrile episode can be used as a predictor for severe dengue infection. The increased and decreased levels at different time points can indicate the disease progression related to vascular leakage in dengue hemorrhagic fever/dengue shock syndrome patients.

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.

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.

The use of recombinant activated factor VII for controlling life-threatening bleeding in Dengue Shock Syndrome.

To report the use of recombinant activated factor VII (rFVIIa) in controlling life-threatening bleeding episodes in patients with grades III and IV Dengue Hemorrhagic Fever (DHF), also known as Dengue Shock Syndrome. Fifteen patients (seven boys, eight girls), whose median age was 8 years, were enrolled in the study. They were divided into two groups. Group 1 included nine patients, mainly grade III, waiting for platelet concentrate, and group 2 included six patients, mainly grade IV, who had already received platelet concentrate with unresponsiveness. A single dose or repeated doses of 100 μg/kg rFVIIa was/were given at intervals of 4 h according to the bleeding symptoms. The median times from the onset of bleeding to rFVIIa initiation were 6.5 and 29.8 h in groups 1 and 2, respectively. Each patient received one to three doses. An effective response was found in eight patients (53.3%), including six patients in group 1 and two patients in group 2. They had complete cessation of bleeding without recurrence for 48 h. An ineffective response was found in seven patients (46.7%) including three patients in group 1 and four patients in group 2 for which the bleeding recurred (n = 2), temporarily slowed down (n = 3), continued (n = 1) or occurred at a new site (n = 1). These included three patients in profound shock 24–48 h before referral to comprehensive treatment centers, two patients receiving ibuprofen before hospitalization, one patient with extensive volume overloading, and one patient requiring surgical intervention to ligate the torn intercostal artery and vein. The platelet concentrate was promptly transfused to stop bleeding in patients with ineffective responses. The results revealed that the earlier initiation of rFVIIa in the mainly grade III DHF in group 1 yielded a higher effective response (66.7%) than the delayed initiation in the mainly grade IV DHF in group 2 (33.3%). Moreover, patients previously receiving ibuprofen or volume expander of low molecular weight dextran or urea-linked gelatin tended to have lower effective responses (28.6%) than patients without associated medication (75.0%). Ultimately, three of six patients with grade IV DHF died, while all nine patients with grade III DHF survived. Thus, the case-fatality rate in this study was 20%. No clinical evidence of thromboembolic complications was observed. rFVIIa seems to be effective in restoring hemostasis in a limited series of patients with Dengue Shock Syndrome exhibiting life-threatening bleeding episodes. Further study is warranted.

Severe Nonfebrile Dengue Infection in an Adolescent After Postoperative Kidney Transplantation: A Case Report

We herein have reported a case of severe nonfebrile dengue infection complicated with refractory pancytopenia and a large perinephric hematoma with shock in a 16-year-old adolescent during the early postoperative period after kidney transplantation. After the diagnosis of end-stage renal disease she underwent living-related kidney transplantation. Thirteen days after successful transplantation, she exhibited a notable amount of ascites, bilateral pleural effusions, thrombocytopenia, and increased hemoglobin without pre-existent fever. Further investigation revealed positive dengue nonstructural protein 1 antigen (dengue NS1 Ag) and dengue virus serotype 1 by a reverse transcriptase-polymerase chain reaction (RT-PCR) in the patients serum. She exhibited hemophagocytic syndrome, manifested by refractory pancytopenia and refractory anemia resulting in hypovolemic shock and acute graft failure on day 28 posttransplantation. The anemia was attributed to a large hematoma around the transplanted kidney requiring surgical evacuation of clotted blood. Postoperatively, she gradually recovered with resolution of thrombocytopenia and excellent graft function. Persistent dengue antigenemia and viremia was shown by dengue NS1 Ag and RT-PCR of dengue serotype-1. The viremia was present longer than the dengue antigenemia. Dengue-specific immunoglobulin M (IgM) and IgG by enzyme-linked immunosorbent assay confirmed the primary dengue infection and evidence of a recent donor dengue infection.

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

Abstract 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.

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.