Longitudinal Analysis of Dengue Virus-Specific Memory T Cell Responses and Their Association With Clinical Outcome in Subsequent DENV Infection.

Memory T cells resulting from primary dengue virus (DENV) infection are hypothesized to influence the clinical outcome of subsequent DENV infection. However, the few studies involving prospectively collected blood samples have found weak and inconsistent associations with outcome and variable temporal trends in DENV-specific memory T cell responses between subjects. This study used both ex-vivo and cultured ELISPOT assays to further evaluate the associations between DENV serotype-cross-reactive memory T cells and severity of secondary infection. Using ex-vivo ELISPOT assays, frequencies of memory T cells secreting IFN-γ in response to DENV structural and non-structural peptide pools were low in PBMC from multiple time points prior to symptomatic secondary DENV infection and showed a variable response to infection. There were no differences in responses between subjects who were not hospitalized (NH, n=6) and those who were hospitalized with dengue hemorrhagic fever (hDHF, n=4). In contrast, responses in cultured ELISPOT assays were more reliably detectable prior to secondary infection and showed more consistent increases after infection. Responses in cultured ELISPOT assays were higher in individuals with hDHF (n=8) compared to NH (n=9) individuals before the secondary infection, with no difference between these groups after infection. These data demonstrate an association of pre-existing DENV-specific memory responses with the severity of illness in subsequent DENV infection, and suggest that frequencies of DENV-reactive T cells measured after short-term culture may be of particular importance for assessing the risk for more severe dengue disease.

Dengue virus induces interferon-ß by activating RNA sensing pathways in megakaryocytes.

Activation of innate receptors in megakaryocytes (MKs) may affect the ability to produce functional platelets. Low platelet count is one of the clinical manifestations of dengue virus (DENV) infection. In MKs, the effect of innate receptors during DENV-infection is not well studied. Here we used MEG-01 cells to investigate DENV serotype 2 induced innate receptors in these cells. DENV RNA was estimated by qRT-PCR in the culture supernatant. The expression of innate receptors was determined by western blot and qPCR. DENV infection led to increased expression of RIG-I at 24 hrs post-infection (hpi) and MDA-5 at 48 and 72 hpi (p<0.05). However, no change in the expression of TLR3 at protein level was observed. Activation of MDA-5 resulted in increased expression of IFN-ß and ISG-15 in DENV infected MEG-01 cells, which was further confirmed by MDA-5 siRNA treatment. Apart from inducing innate receptors, DENV significantly decreases the expression of CD61, an activation marker of megakaryocyteson MEG-01 cells as observed by flow cytometry analysis (p<0.01). Results from this study confirm that DENV infection activates the type-I interferon in megakaryocytes and may play a significant role in maturation and development.

Complicaciones oculares asociadas a la fiebre por dengue / Ophthalmic complications associated to dengue fever

RESUMEN La infección por el virus del dengue va en aumento en las regiones tropicales de Asia, África y América. Se estima que se producen de 50 a 100 millones de casos de esta enfermedad al año. En los últimos tiempos han aumentado los reportes de manifestaciones oculares en estos pacientes, las cuales ocurren en un rango de 5 a 7 días posteriores al inicio de los síntomas, aunque también pueden ocurrir más tarde, y generalmente existe buen pronóstico visual. Se realiza una revisión bibliográfica con el objetivo de ampliar el conocimiento sobre un tema poco tratado en nuestro medio. Se consultaron fundamentalmente artículos científicos de revistas, publicados en las bases de datos PubMED y Cochrane, así como textos básicos que abordan este tema en los últimos 5 años, a través de Google académico como motor de búsqueda. Se constató que se han reportado manifestaciones oculares en pacientes con dengue que van desde hallazgos en el segmento anterior sin afectación visual, hasta cuadros más intensos que interesan las estructuras del polo posterior del ojo. La fisiopatología de estos hallazgos aún se encuentra en estudio y no existe consenso para su tratamiento. A pesar de que el pronóstico visual de estas alteraciones es bueno, se reportan casos donde no es así y se precisa mayor comprensión sobre la fisiopatología de estas para un abordaje terapéutico más adecuado en cada caso(AU)

ABSTRACT Infection by dengue virus is on the increase in tropical regions of Asia, Africa and America. It has been estimated that 50 to 100 million cases of this disease occur every year. Recent years have witnessed a rise in the number of reports of ocular manifestations in dengue patients. These manifestations appear 5 to 7 days after symptom onset, though they could also occur later, and the visual prognosis is generally good. A bibliographic review was conducted with the purpose of broadening knowledge about a topic not commonly dealt with in our environment. The search was mainly aimed at scientific papers from journals, published in the databases PubMed and Cochrane, as well as basic texts addressing the study topic in the last 5 years, using the search engine Google Scholar. Ocular manifestations were found to have been reported in dengue patients. These range from findings in the anterior segment without any visual alteration to more intense episodes affecting the structures of the posterior pole of the eye. The physiopathology of these findings is still being studied, and there is no consensus about its treatment. Despite the good visual prognosis of these alterations, cases have been reported of a different outcome. Therefore, a better understanding is required of their physiopathology to achieve a more appropriate therapy for each case(AU)

Mast cell mediators in relation to dengue severity: A systematic review and meta-analysis.

BACKGROUND: Degranulation of mast cells (MCs) releases several mediators such as vascular endothelial growth factor (VEGF), chymase, tryptase, histamine, and cytokines, which all have important roles in the severity of dengue infection. We aimed to investigate the role of MCs in severity of dengue. METHODS: We searched for relevant studies in 10 databases on 15 August 2016. Meta-analysis (MA) was conducted by R version 3.5.0. RESULTS: We included 24 studies. in vivo and in vitro studies showed higher MC products released from infected mice/cells with dengue virus. In addition, when administering MC stabilizers or antihistaminic drugs, there was a decrease in vascular/capillary permeability. In human and at early stages, studies revealed an insignificant difference in VEGF levels in dengue fever (DF) versus dengue hemorrhagic fever (DHF) (standardized mean difference [SMD] 0.145; 95% confidence interval [CI], -0.348-0.638). Meanwhile, at acute stages and compared with healthy controls, high heterogeneity with an inconclusive difference in VEGF levels were noted in DF and DHF. However, pooled serum and plasma levels of VEGF were increased significantly in dengue shock syndrome (DSS) versus healthy controls (SMD 0.65; 95% CI, 0.3-0.95). There were also significantly higher chymase levels in DHF patients compared with DF during the acute phase (MD -6.531; 95% CI, -12.2 to -0.9). CONCLUSION: VEGF and chymase levels are mediators in dengue pathogenesis. However, limited data were available to support their role in severe dengue cases. Further studies are needed to evaluate the function of other mediators in dengue severity.

The clinical significance of myeloid-derived suppressor cells in dengue fever patients.

BACKGROUND: Myeloid-derived suppressor cells (MDSCs) play immunosuppressive roles in cancers and some infectious diseases; however, their role in dengue fever (DF) remains unknown. This study evaluated the clinical significance of MDSCs in DF patients. METHODS: This study comprised 178 non-severe DF patients, 20 non-dengue fever (NDF) controls, and 30 healthy donors. The DF patients were divided into the following five groups based on the fever duration from its onset to the day of sample collection: fever duration of 1-2, 3-4, 5-6, 7-8, and > 9 days. Among these DF patients, 14 were monitored for eight days, and their peripheral blood samples were collected every two days. The mononuclear cells were isolated and analyzed using flow cytometry. The correlation between the MDSCs and clinical and immunological indicators of the DF patients was evaluated using Spearman analysis. RESULTS: The count of the peripheral blood MDSCs, especially monocytic MDSCs, of the 178 DF patients were dramatically higher than those of the NDF and healthy controls, and remarkably decreased with the fever duration. Moreover, the MDSC count correlated with some indicators, including the dengue viral load (rho = 0.367, p < .001), body temperature (rho = 0.263, p = .005), prothrombin time (rho = 0.475, p < .001), CD4+ T cell number (rho = - 0.317, p < .001), CD8+ T cell number (rho = - 0.361, p < .001), "programmed cell death protein 1" (PD-1) (rho = - 0.347, p < .001), "T cell immunoglobulin domain and mucin domain-3" (Tim3) (rho = - 0.258, p = .001), interferon-α (IFN-α) (rho = 0.43, p < .001), and "regulated upon activation normal T-cell expressed and secreted" (RANTES) (rho = 0.278, p = .019). Furthermore, the level of arginase-1, but not nitric oxide, was higher in the DF patients than in the healthy controls and was closely related to the number of MDSCs (rho = 0.265, p = .024). CONCLUSIONS: Our study reveals a significant correlation between MDSCs and DF clinical indicators, posing MDSCs as potential target cells for DF treatment.

Perfil clínico, epidemiológico y geográfico de casos de dengue durante el fenómeno El Niño Costero 2017, Lambayeque-Perú / Clinical, epidemiological and geographic profile of dengue cases during El Niño Costero Phenomenon 2017, Lambayeque-Perú

Introducción: En la actualidad, el dengue persiste como un problema latente para la salud pública en nuestro país; se debe tener en cuenta también que los casos de dengue han presentado una tendencia creciente en los últimos 5 años, en 2017 una cifra de 76 093 casos (3.03 veces más casos en relación con 2016), y 93 muertes, la mayor cifra en los últimos 5 años. Objetivo: Describir el perfil clínico, epidemiológico y geográfico del dengue en la Red EsSalud Lambayeque 2017, durante El Niño Costero. Material y métodos: Pacientes captados por sistema de vigilancia epidemiológica que cuentan con ficha epidemiológica con diagnóstico clínico de dengue de todas las edades, ambos sexos, atendidos en la red asistencial EsSalud-Lambayeque durante el fenómeno El Niño Costero. Se utilizó estadística descriptiva con cálculo de frecuencias absolutas y relativas para las variables cualitativas y media con desviación estándar para las cuantitativas y software libre QGis 2.14 para georreferenciación. Resultados: La edad fue 7.2 + 20.4 años, 27,9 por ciento procedentes de Chiclayo, 52,9 por ciento fueron mujeres, 77 por ciento presentaron dengue sin signos de alarma, 1,5 por ciento fallecidos. De los 874 casos, 335 (38,3 por ciento ) casos fueron positivos 213 (63,5 por ciento ) por laboratorio. La clínica más frecuente fue fiebre, cefalea, artralgia y mialgia. El signo de alarma más frecuente fue disminución de plaquetas. Conclusiones: El dengue afectó en mayor frecuencia a la población adulta, femenina, procedente de Chiclayo; clínicamente sin signos de alarma(AU)

Introduction: At present, dengue fever persists as a latent problem for public health in our country. It should also be borne in mind that the cases of dengue fever have presented a growing trend during the last 5 years, with a number of 76 093 cases in 2017 (3.03 times more cases with respect to the year 2016); and 93 deaths, which represents the highest figure in the last 5 years. Objective: To describe the clinical, epidemiological and geographical profile of dengue fever in the EsSalud Lambayeque Network 2017, during El Niño Costero Phenomenon. Material and Methods: Patients of all ages and both sexes with an epidemiological record of a clinical diagnosis of dengue identified by the epidemiological surveillance system, in the EsSalud-Lambayeque Health Care Network, during El Niño Costero Phenomenon. Descriptive statistics with calculation of absolute and relative frequencies for qualitative variables and mean with standard deviation for quantitative and free software QGis 2.14 for georeferencing. Results: The age was 7.2 + 20.4 years, 27.9 percent from Chiclayo, 52.9 percent were women; 77 percent had dengue without warning signs, 1.5 percent died. Of the 874 cases, 335 ones (38.3 percent) were positive, and 213 (63.5 percent) were diagnosed from reference laboratory. The most frequent clinical symptoms and signs were fever, headache, arthralgia and myalgia. The most frequent alarm sign was decrease in platelet. Conclusions: Dengue fever affected the adult female population from Chiclayo more frequently; presenting no clinical warning signs(AU)

Genetic variants of MICB and PLCE1 and associations with the laboratory features of dengue.

BACKGROUND: A previous genome-wide association study identified 2 susceptibility loci for severe dengue at MICB rs3132468 and PLCE1 rs3740360 and further work showed these mutations to be also associated with less severe clinical presentations. The aim of this study was to determine if these specific loci were associated with laboratory features of dengue that correlate with clinical severity with the aim of elucidating the functional basis of these genetic variants. METHODS: This was a case-only analysis of laboratory-confirmed dengue patients obtained from 2 prospective cohort studies and 1 randomised clinical trial in Vietnam (Trial registration: ISRCTN ISRCTN03147572. Registered 24th July 2012). 2742 dengue cases were successfully genotyped at MICB rs3132468 and PLCE1 rs3740360. Laboratory variables were compared between genotypes and stratified by DENV serotype. RESULTS: The analysis showed no association between MICB and PLCE1 genotype and early viraemia level, platelet nadir, white cell count nadir, or maximum haematocrit in both overall analysis and in analysis stratified by serotype. DISCUSSION: The lack of an association between genotype and viremia level may reflect the sampling procedures within the included studies. The study findings mean that the functional basis of these mutations remains unclear. TRIAL REGISTRATION: ISRCTN ISRCTN03147572 . Registered 24th July 2012.

Dengue virus transmission by blood stem cell donor after travel to Sri Lanka; Germany, 2013.

Three days after donation of peripheral blood stem cells to a recipient with acute myeloblastic leukemia, dengue virus was detected in the donor, who had recently traveled to Sri Lanka. Transmission to the recipient, who died 9 days after transplant, was confirmed.

Emerging concepts in dengue pathogenesis: interplay between plasmablasts, platelets, and complement in triggering vasculopathy.

Dengue is a mosquito-borne disease caused by infection with dengue virus (DENV) that represents a serious and expanding global health threat. Most DENV infections are inapparent or produce mild and self-limiting illness; however a significant proportion results in severe disease characterized by vasculopathy and plasma leakage that may culminate in shock and death. The cause of dengue-associated vasculopathy is likely to be multifactorial but remains essentially unknown. Severe disease is manifest during a critical phase from 4 to 7 days after onset of symptoms, once the virus has disappeared from the circulation but before the peak of T-cell activation, suggesting that other factors mediate vasculopathy. Here, we present evidence for a combined role of plasmablasts, complement, and platelets in driving severe disease in DENV infection. Massive expansion of virus-specific plasmablasts peaks during the critical phase of infection, coincident with activation of complement and activation and depletion of platelets. We propose a step-wise model in which virus-specific antibodies produced by plasmablasts form immune complexes, leading to activation of complement and release of vasoactive anaphylatoxins. Platelets become activated through binding of complement- and antibody-coated virus, as well as direct binding of virus to DC-SIGN, leading to the release of inflammatory microparticles and cytokines and sequestration of platelets in the microvasculature. We suggest that the combined effects of anaphylatoxins, inflammatory microparticles, and platelet sequestration serve as triggers of vasculopathy in severe dengue.

Patogénesis del dengue / Pathogenesis of dengue

Las cuatro subespecies del dengue pertenecen a los arbovirus ARN trasmitidos por el Aedes aegypti y son los agentes causales del dengue. La enfermedad puede manifestarse desde una infección asintomática o como fiebre inespecífica hasta una enfermedad hemorrágica y un síndrome de choque que pueden causar la muerte. Los mecanismos de la patogénesis del dengue son todav¡a desconocidos por la falta de un modelo animal para realizar los estudios a nivel de los vasos sanguíneos. Sin embargo, se plantean hipótesis y nuevos estudios para entender la clínica y el manejo de una enfermedad que está  en aumento, especialmente, en la metrópoli de Lima.

The four subspecies of dengue belong to RNA arbovirus transmitted by the Aedes aegypti, which are the causative agents of dengue. The disease can occur from asymptomatic infection or nonspecific fever to a hemorrhagic disease and shock syndrome which can be fatal. The mechanism of pathogenesis of dengue are still unknown because of the lack of an animal model for studies at the level of the blood vessels, however, new hypothesis and new studies are proposed to understand the clinical management of this disease which is increasing especially in metropolitan Lima.

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 patient's 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.

Contribution of macrophage migration inhibitory factor to the pathogenesis of dengue virus infection.

Dengue fever is an emerging viral disease transmitted by arthropods to humans in tropical countries. Dengue hemorrhagic fever (DHF) is escalating in frequency and mortality rates. Here we studied the involvement of macrophage migration inhibitory factor (MIF) in dengue virus (DENV) infection and its pathogenesis. Patients with DHF had elevated plasma concentrations of MIF. Both leukocytes from these patients and macrophages from healthy donors infected in vitro with DENV showed a substantial amount of MIF within lipid droplets. The secretion of MIF by macrophages and hepatocytes required a productive infection and occurred without an increase in gene transcription or cell death, thus indicating active secretion from preformed stocks. In vivo infection of wild-type and mif-deficient (Mif(-/-)) mice demonstrated a role of MIF in dengue pathogenesis. Clinical disease was less severe in Mif(-/-) mice, and they exhibited a significant delay in lethality, lower viremia, and lower viral load in the spleen than wild-type mice. This reduction in all parameters of severity on DENV infection in Mif(-/-) mice correlated with reduced proinflammatory cytokine concentrations. These results demonstrated the contribution of MIF to the pathogenesis of dengue and pointed to a possible beneficial role of neutralizing MIF as an adjunctive therapeutic approach to treat the severe forms of the disease.

Sensoriamento remoto e modelagem espacial nos estudos dos processos endêmicos-epidêmicos em áreas urbanas: o caso da dengue no município de Niterói - Estado do Rio de Janeiro / Remote sensing and spatial modeling studies of the processes endemic-epidemic in urban areas: the case of dengue in the municipality of Niterói - Rio de Janeiro State

O presente estudo teve por objetivo analisar a distribuição da dengue, no período de 1998 a 2007, segundo indicadores socioeconômicos e ambientais, com a finalidade de identificar áreas prioritárias para ações de controle da dengue, utilizando para isso ferramentas de análise espacial e técnicas de modelagem estatística. O trabalho está apresentado em três artigos. O primeiro artigo teve como objetivo verificar a aplicação da metodologia de análise de cluster visando, a partir de indicadores socioeconômicos, caracterizar áreas prioritárias para ações de controle da dengue. No segundo, buscou-se através de classificação de imagem orientada a objetos identificar possíveis indicadores de “uso do solo” associados à dengue. E, no terceiro buscou-se mediante a utilização de análise espacial e modelagem estatística verificar a distribuição espacial da incidência da dengue e sua relação com as desigualdades socioespaciais nos setores censitários da região oceânica do município de Niterói. A metodologia de análise de cluster mostrou-se aplicável para o reconhecimento de áreas prioritárias para ações de controle da dengue em Niterói. Essas áreas apresentaram má condição de infraestrutura de serviços de saneamento, elevado incremento populacional e maior percentual de favelas. A classificação orientada a objetos nos traz novas perspectivas na construção de possíveis indicadores, oriundos da imagem de satélite, associados com a dengue. Os resultados mostram que a proporção de piscinas apresenta correlação com a incidência da dengue segundo setores censitários, sugerindo que a transmissão ocorre próxima as áreas residenciais. A modelagem estatística evidenciou que as taxas apresentam associação com as carências na infraestrutura de saneamento (maior proporção de domicílios particulares permanentes com abastecimento de água do tipo poço ou nascente na propriedade) e com a maior proporção de piscinas...

This study aimed to analyze the distribution of dengue between 1998 and 2007, according to socioeconomic and environmental indicators, with the aim of identifying priority areas for dengue control actions, making use of spatial analysis tools and statisticsmodeling techniques. The work is presented in three papers. The first article was to verify the application of the methodology of cluster analysis in order to, from socioeconomic indicators, characterize priority areas for dengue control actions. In the second, weattempted to sort through object-oriented image to identify possible indicators of "land use" associated with dengue. And third we sought through the use of spatial analysis and statistical modeling to determine the spatial distribution of dengue incidence and itsrelationship to socio-spatial inequalities in census tracts of the oceanic region of Niterói. The methodology of cluster analysis showed to apply for recognition of priority areas for actions to control dengue in Niteroi. These areas showed poor condition of infrastructure,sanitation services, high population growth and a higher percentage of slums. Classification object oriented brings new perspectives in the construction of possible indicators, derived from satellite image associated with dengue. The results show that the proportion of pools correlates with the dengue incidence according to census tracts, suggesting that transmissionoccurs near residential areas. The statistical modeling showed that the rates have association with the shortcomings in sanitation infrastructure (higher proportion of permanent privatehouseholds with water supply from wells or springs in such property) and the highest proportion of pools...

Diferencias en la susceptibilidad a la deltametrina en poblaciones de Aedes aegypti de Trujillo, Venezuela / Different susceptibility to deltamethrin in Aedes aegypti populations from Trujillo state, Venezuela

El dengue es un importante problema de salud pública en Venezuela, donde aedes aegypti es el principal vector. El propósito de este estudio fue determinar el estado de la susceptibilidad a la deltametrina en nueve poblaciones naturales de A. aegypti del estado Trujillo, en comparación con la cepa susceptible Rockefeller. Los bioensayos fueron llevados a cabo siguiendo la metodología de la Organización Mundial de la Salud. Las poblaciones Trujillo, Pampán, Pampanito, Flor de Patria, Motatán, Tres Esquinas y Cubita mostraron valores de mortalidades comprendidas entre 89% y 97%, y KDT50 entre 15,7 min y 24,1 min, sugiriendo la posibilidad de resistencia la cual debe ser confirmada. Las poblaciones Monay y Filo fueron susceptibles, con KDT50 de 15,5 y 20,2 min respectivamente, y mortalidades a las 24 horas de 99 y 98%. Estos resultados deben ser considerados al momento de diseñar el programa de control del vector para asegurar la efectividad del mismo.

Dengue is an important public health problem in Venezuela, where Aedes aegypti is the main vector. The purpose of this study was to determine the status of susceptibility to deltamethrin in nine natural populations of A. aegypti from Trujillo state compared with the susceptible Rockefeller strain. Bioassays were carried out following the methodology of the World Health Organization. The values of mortalities were found between 89% and 97%, allowing categorize the populations from Trujillo, Pampan, Pampanito, Flor de Patria, Motatan, Tres Esquinas and Cubita as resistant under verification, with values KDT50 between 15.7 min and 24.1 min, suggesting the possibility of resistance which must be confirmed and the populations from Monay and Filo as susceptible, with a KDT50 of 15.5 and 20.2 min, respectively, and 99 and 98% mortality at 24 hours. These results should be considered when designing programs for vector control to ensure those are effective to control A. aegytpti populations.