Characterization of the cell-mediated immune response to Takeda’s live-attenuated tetravalent dengue vaccine in adolescents participating in a phase 2 randomized controlled trial conducted in a dengue-endemic setting

BackgroundAs robust dengue-specific CD4+ and CD8+ T cell responses are essential for protective immunity, we assessed cell-mediated immune (CMI) responses to a DENV-2-based dengue tetravalent vaccine candidate (TAK-003) in adolescents living in Panama, a dengue-endemic country.MethodsPeripheral blood mononuclear cells were collected from a subset of 67 participants ≥ 10 years old included in a phase 2 clinical trial of TAK-003 (Clinicaltrials.gov: NCT02302066). Following stimulation with dengue peptides, the frequency, magnitude, and cross-reactivity of the CD8+ and CD4+ T cell IFN-γ, TNF-α and IL-2 responses were assessed by flow cytometry.ResultsIntracellular cytokine staining identified NS1, NS3, and NS5 as the most common non-structural (NS) targets of the CD4+ T-cell response (IFN-γ+); NS3 and NS5 were the main NS targets of the CD8+ T cell response (IFN-γ+). Both CD4+ and CD8+ T-cell responses were multi-functional (IFN-γ + TNF-α + IL-2+) and cross-reactive against DENV-1, -3, and -4 serotypes. Similar responses were seen in all CMI assessments irrespective of participant baseline status for dengue neutralizing antibodies and T cells.ConclusionsTAK-003 elicited cross-reactive, multi-functional CD4+ and CD8+ T-cell responses, irrespective of dengue pre-exposure.     

Carotid intima-media thickness,lipid profile,serum amyloid A and vitamin D status in children with familial Mediterranean fever

Aim of the workIt was to estimate the carotid intima-media thickness (CIMT), lipid profile, serum amyloid A and vitamin D in Familial Mediterranean Fever (FMF) patients and to explore the relationship between CIMT and FMF.Patients and methodsThe study comprised forty-five FMF patients diagnosed during the attack free period and 40 healthy children with similar demographic features as control. The diagnosis of the FMF cases was confirmed by clinical, laboratory assessments and confirmed by the molecular diagnosis. The CIMT, lipid profile, complete blood picture, serum amyloid A (SAA) levels, vitamin D and the growth pattern were investigated.ResultsThe study showed no significant difference of CIMT among patients and controls, significant decrease of vitamin D levels, while lipid profile parameters, triglyceride (TG) to HDL-Cholesterol (HDL-C) ratio, serum amyloid A were significantly increased. A significant correlation was present between the CIMT with the serum cholesterol, low density lipoprotein and triglycerides as well as between SAA and the number of attacks. In addition, vitamin D levels showed significant negative correlation with colchicine. M694I mutation was the most prevalent among FMF patients. Growth parameters were normal in FMF cases.ConclusionThis study sheds light that the normal CIMT in the FMF patients makes it difficult to describe the children as having subclinical atherosclerosis although the higher TG/HDL ratio reflects their risk of atherosclerosis. Moreover, significant decrease of vitamin D in FMF patients was observed. The growth parameters of the FMF patients on regular treatment of colchicine were not affected.     

Single nucleotide polymorphisms in immune system genes and their association with clinical symptoms persistence in dengue-infected persons

This study was undertaken to determine the prevalence of dengue clinical symptom persistence during 60 days of disease follow up, in patients of Espírito Santo state (ES)-Brazil and to evaluate the relation of single nucleotide polymorphisms (SNPs) in FcγRIIa, CD209, VDR, TNF-α, IL-4, IL-6 and IFN-γ genes with symptom persistence. During 2012–2013, 96 blood samples from individuals diagnosed with symptomatic dengue were collected. Clinical symptom persistence in 60 days of follow-up was assessed by a clinical and epidemiological questionnaire filled in 4 interviews. SNP genotyping was performed by polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP). In two months of monitoring the dengue infection, we observed that symptoms persisted in 38.5% (37/96) of dengue patients at the end of the first month (D30) and in 11.5% (11/96) of dengue patients at the end of the second month (D60). Our results show an association between FcγRIIa, TNF-α and IL-6 gene SNPs and symptom persistence and an association trend with CD209, IL-4 and IFN-γ gene SNPs. Our findings may increase the knowledge on the pathophysiological mechanisms of persistent symptoms of infection with the dengue virus (DENV) and thus help the clinical management of patients.     

The utility of inflammatory and endothelial factors in the prognosis of severe dengue

BackgroundSevere dengue is associated with a considerable risk of mortality, and there is currently a lack of appropriate prognostic biomarkers to predict its severity. Pathogenesis of severe dengue is characterized by overt inflammation, endothelial activation, and increased vascular permeability. The current study investigates the utility of endothelial, inflammatory, and vascular permeability factors as biomarkers to identify dengue severity, which could improve disease prognosis and management.MethodsThe dengue-positive subjects were classified based on seropositivity for NS1, IgM, and IgG. The samples in each group were quantified for basic clinical investigations. The levels of Interleukin-6 (IL-6), Tumor necrosis factor receptor 1 (TNFR1), EOTAXIN, Monocyte chemoattractant protein-1 (MCP-1), Monokine induced by interferon-gamma (MIG), Intercellular adhesion molecule-1 (ICAM-1), Vascular cell adhesion molecule-1 (VCAM-1), Thrombomodulin, and Angiopoietin-2 were estimated in all serum samples using the multiplex bead-based assay.ResultsIgG seropositive dengue patients showed abnormal laboratory characteristics and severe dengue symptoms. Among the studied markers, only IL-6, TNFR1, ICAM-1, VCAM-1, Thrombomodulin, and Angiopoietin-2 were significantly elevated in IgG seropositive patients compared to healthy controls. Increased IL-6 and TNFR1 levels were associated with decreased platelet count and elevated Hematocrit levels in IgG seropositive patients. Furthermore, ROC curve analysis indicated that IL-6, TNFR1, Thrombomodulin, and Angiopoietin-2 showed good potential for predicting dengue severity.ConclusionInflammatory markers IL-6 and TNFR1, and endothelial factors Angiopoietin-2 and Thrombomodulin, could serve as prognostic markers for severe dengue. These findings also encourage the future study of these biomarkers in the pathogenesis of severe dengue infection.     

Rapid diagnostic tests for determining dengue serostatus: a systematic review and key informant interviews

ObjectivesVaccination for dengue with the live attenuated tetravalent CYD-TDV vaccine (Dengvaxia®) is only recommended in individuals who have had prior dengue virus (DENV) infection. Rapid diagnostic tests (RDT) for past DENV infection would offer a convenient method for pre-vaccination screening at point-of-care. A systematic review was conducted to evaluate the performance of current dengue RDTs for determining dengue serostatus, using IgG antibodies against DENV as a marker of past infection.MethodsPubMed and EMBASE databases were searched from 2000 to 2018 to identify studies evaluating dengue RDTs in individuals with known or possible previous DENV infection. Study quality was evaluated using GRADE and QUADAS-2 criteria. Semi-structured interviews were also performed with available dengue RDT manufacturers.ResultsThe performance of four dengue IgG RDTs was determined in 3137 individuals across ten studies conducted in 13 countries, with serum used in most of the studies. No studies reported data for determining dengue serostatus, and limited data were available regarding cross-reactivity with other viruses. The majority of studies demonstrated sensitivities and specificities between 80% and 100% for dengue IgG detection in samples from secondary infection or convalescent time-points after recent infection.ConclusionsAlthough current dengue IgG RDTs have shown reasonable performance compared with laboratory-based tests in secondary infection, additional research is needed to determine how RDTs would perform in relevant populations targeted for vaccination. New RDTs or modifications to current RDTs are feasible and may optimize the performance of these tests for use in a pre-vaccination screening approach.     

Febrile illness in Asia: gaps in epidemiology,diagnosis and management for informing health policy

BackgroundIncreasing evidence is becoming available on the aetiology and management of fevers in Asia; the importance of these fevers has increased with the decline in the incidence of malaria.AimsTo conduct a narrative review of the epidemiology and management of fevers in South and South-East Asia and to highlight gaps in our knowledge that impair evidence-based health policy decisions.SourcesA narrative review of papers published since 2012 on developments in fever epidemiology, diagnosis and treatment in South and South-East Asia. The papers that the authors felt were pivotal, from their personal perspectives, are discussed.ContentWe identified 100 studies. Among the 30 studies (30%)—including both children and adults—that investigated three or more pathogens, the most frequently reported fever aetiology was dengue (reported by 15, 50%), followed by leptospirosis (eight, 27%), scrub typhus (seven, 23%) and Salmonella serovar Typhi (six, 20%). Among four studies investigating three or more pathogens in children, dengue and Staphylococcus aureus were the most frequent, followed by non-typhoidal Salmonella spp, Streptococcus pneumoniae, Salmonella serovar Typhi, and Orientia tsutsugamushi. Increased awareness is needed that rickettsial pathogens are common but do not respond to cephalosporins, and that alternative therapies, such as tetracyclines, are required.ImplicationsMany key gaps remain, and consensus guidelines for study design are needed to aid comparative understanding of the epidemiology of fevers. More investment in developing accurate and affordable diagnostic tests for rural Asia and independent evaluation of those already on the market are needed. Treatment algorithms, including simple biomarker assays, appropriate for empirical therapy of fevers in different areas of rural Asia should be a major aim of fever research. Enhanced antimicrobial resistance (AMR) surveillance and openly accessible databases of geography-specific AMR data would inform policy on empirical and specific therapy. More investment in innovative strategies facilitating infectious disease surveillance in remote rural communities would be an important component of poverty reduction and improving public health.     

Contrasting associations of polymorphisms in FcγRIIa and DC-SIGN with the clinical presentation of dengue infection in a Mexican population

Dengue virus (DENV) causes a spectrum of illness from asymptomatic infection, to a mild febrile illness, to occasional more severe complications including hemorrhage and shock. Dengue is endemic in the state of Morelos, Mexico. Two single nucleotide polymorphisms (SNPs), rs1801274 of FcγRIIa and rs4804803 of DC-SIGN, have been associated with protection from or susceptibility to severe dengue infection. Both of these polymorphisms are located in genes for receptors with important roles in dengue pathogenesis, and their relationship with the clinical presentation of dengue infection in Mexican populations is unknown. In this study, real-time PCR was used to characterize the distribution of rs1801274 and rs4804803 in subjects with asymptomatic dengue infection (n = 145), uncomplicated dengue (n = 67), and severe dengue (n = 36) in Morelos. In contrast with previous studies, the histidine (A) variant of rs1801274 was associated with more mild infection: carrying the histidine allele (either homozygous or heterozygous) was associated with protection from symptomatic infection compared with asymptomatic (OR 0.51, p = 0.038). Histidine homozygotes were also less likely to present severe dengue (OR 0.34, p = 0.05). Logistic regression models confirm this association (OR 0.48, p = 0.04) and also indicate that the G allele of rs4804803 is associated with symptomatic dengue (OR 2.3, p = 0.08), after accounting for other biological factors including history of infection. This variant was rare in this study population, with a frequency of 5.4%. These findings reflect the complexity of influences on the development of severe dengue infection. The inclusion of asymptomatic infections and adjusted case definitions likely do not explain the entire disparity with previous findings. Interactions with other polymorphisms may explain why the association of rs1801274 is reversed in this population compared to others. This study demonstrates the importance of genetic association studies in multiple genetically distinct populations.