Dengue virus

About: Dengue virus is a research topic. Over the lifetime, 12671 publications have been published within this topic receiving 461406 citations. The topic is also known as: DENV.

Evaluation of the Traditional and Revised WHO Classifications of Dengue Disease Severity

Abstract: Dengue is a major public health problem worldwide and continues to increase in incidence. Dengue virus (DENV) infection leads to a range of outcomes, including subclinical infection, undifferentiated febrile illness, Dengue Fever (DF), life-threatening syndromes with fluid loss and hypotensive shock, or other severe manifestations such as bleeding and organ failure. The long-standing World Health Organization (WHO) dengue classification and management scheme was recently revised, replacing DF, Dengue Hemorrhagic Fever (DHF), and Dengue Shock Syndrome (DSS) with Dengue without Warning Signs, Dengue with Warning Signs (abdominal pain, persistent vomiting, fluid accumulation, mucosal bleeding, lethargy, liver enlargement, increasing hematocrit with decreasing platelets) and Severe Dengue (SD; dengue with severe plasma leakage, severe bleeding, or organ failure). We evaluated the traditional and revised classification schemes against clinical intervention levels to determine how each captures disease severity using data from five years (2005–2010) of a hospital-based study of pediatric dengue in Managua, Nicaragua. Laboratory-confirmed dengue cases (n = 544) were categorized using both classification schemes and by level of care (I–III). Category I was out-patient care, Category II was in-patient care that did not meet criteria for Category III, which included ICU admission, ventilation, administration of inotropic drugs, or organ failure. Sensitivity and specificity to capture Category III care for DHF/DSS were 39.0% and 75.5%, respectively; sensitivity and specificity for SD were 92.1% and 78.5%, respectively. In this data set, DENV-2 was found to be significantly associated with DHF/DSS; however, this association was not observed with the revised classification. Among dengue-confirmed cases, the revised WHO classification for severe dengue appears to have higher sensitivity and specificity to identify cases in need of heightened care, although it is no longer as specific for a particular pathogenic entity as was the traditional schema.

Elevated plasma interleukin-10 levels in acute dengue correlate with disease severity.

Abstract: Dengue viruses, of which there are four serotypes,are the most important arthropod-borne viral infec-tions in the world, accounting for more than 250,000cases of dengue hemorrhagic fever (DHF) and 10,000deaths annually [Monath, 1994]. Infection with dengueviruses can yield different clinical syndromes, includ-ing (1) undifferentiated febrile illness, seen more com-monly in children; (2) dengue fever (DF), a flu-like syn-drome characterized by high fever, headache, retro-orbital pain, myalgias, abdominal pain, nausea, andvomiting; and (3) dengue hemorrhagic fever (DHF), aplasma leak syndrome that, in its most severe form,can be life-threatening [Nimmannitya, 1987].Plasma leakage is a major clinical feature of DHFand tends to occur around the time of defervescence.We have been interested in the events that precede theperiod of plasma leakage to better define its etiology.We have found that dengue virus-specific CD4

Dynamics of the “Popcorn” Wolbachia Infection in Outbred Aedes aegypti Informs Prospects for Mosquito Vector Control

Abstract: Forty percent of the world's population is at risk of contracting dengue virus, which produces dengue fever with a potentially fatal hemorrhagic form. The wMelPop Wolbachia infection of Drosophila melanogaster reduces life span and interferes with viral transmission when introduced into the mosquito Aedes aegypti, the primary vector of dengue virus. Wolbachia has been proposed as an agent for preventing transmission of dengue virus. Population invasion by Wolbachia depends on levels of cytoplasmic incompatibility, fitness effects, and maternal transmission. Here we characterized these traits in an outbred genetic background of a potential target population of Ae. aegypti using two crossing schemes. Cytoplasmic incompatibility was strong in this background, and the maternal transmission rate of Wolbachia was high. The infection substantially reduced longevity of infected adult females, regardless of whether adults came from larvae cultured under high or low levels of nutrition or density. The infection reduced the viability of diapausing and nondiapausing eggs. Viability was particularly low when eggs were laid by older females and when diapausing eggs had been stored for a few weeks. The infection affected mosquito larval development time and adult body size under different larval nutrition levels and densities. The results were used to assess the potential for wMelPop-CLA to invade natural populations of Ae. aegypti and to develop recommendations for the maintenance of fitness in infected mosquitoes that need to compete against field insects.

Dengue virus infection of the Aedes aegypti salivary gland and chemosensory apparatus induces genes that modulate infection and blood-feeding behavior.

Abstract: The female Aedes aegypti salivary gland plays a pivotal role in bloodmeal acquisition and reproduction, and thereby dengue virus (DENV) transmission. It produces numerous immune factors, as well as immune-modulatory, vasodilatory, and anti-coagulant molecules that facilitate blood-feeding. To assess the impact of DENV infection on salivary gland physiology and function, we performed a comparative genome-wide microarray analysis of the naive and DENV infection-responsive A. aegypti salivary gland transcriptomes. DENV infection resulted in the regulation of 147 transcripts that represented a variety of functional classes, including several that are essential for virus transmission, such as immunity, blood-feeding, and host-seeking. RNAi-mediated gene silencing of three DENV infection-responsive genes - a cathepsin B, a putative cystatin, and a hypothetical ankyrin repeat-containing protein - significantly modulated DENV replication in the salivary gland. Furthermore, silencing of two DENV infection-responsive odorant-binding protein genes (OBPs) resulted in an overall compromise in blood acquisition from a single host by increasing the time for initiation of probing and the probing time before a successful bloodmeal. We also show that DENV established an extensive infection in the mosquito's main olfactory organs, the antennae, which resulted in changes of the transcript abundance of key host-seeking genes. DENV infection, however, did not significantly impact probing initiation or probing times in our laboratory infection system. Here we show for the first time that the mosquito salivary gland mounts responses to suppress DENV which, in turn, modulates the expression of chemosensory-related genes that regulate feeding behavior. These reciprocal interactions may have the potential to affect DENV transmission between humans.

Wolbachia uses a host microRNA to regulate transcripts of a methyltransferase, contributing to dengue virus inhibition in Aedes aegypti

Abstract: The endosymbiont Wolbachia is common among insects and known for the reproductive manipulations it exerts on hosts as well as inhibition of virus replication in their hosts. Recently, we showed that Wolbachia uses host microRNAs to manipulate host gene expression for its efficient maintenance in the dengue mosquito vector, Aedes aegypti. Cytosine methylation is mediated by a group of proteins called DNA (cytosine-5) methyltransferases, which are structurally and functionally conserved from prokaryotes to eukaryotes. The biological functions of cytosine methylation include host defense, genome stability, gene regulation, developmental promotion of organs, and lifespan regulation. Ae. aegypti has only one DNA methyltransferase gene (AaDnmt2) belonging to the cytosine methyltransferase family 2, which is the most deeply conserved and widely distributed gene among metazoans. Here, we show that in mosquitoes the introduced endosymbiont, Wolbachia, significantly suppresses expression of AaDnmt2, but dengue virus induces expression of AaDnmt2. Interestingly, we found that aae-miR-2940 microRNA, which is exclusively expressed in Wolbachia-infected mosquitoes, down-regulates the expression of AaDnmt2. Reversely, overexpression of AaDnmt2 in mosquito cells led to inhibition of Wolbachia replication, but significantly promoted replication of dengue virus, suggesting a causal link between this Wolbachia manipulation and the blocking of dengue replication in Wolbachia-infected mosquitoes. In addition, our findings provide an explanation for hypomethylation of the genome in Wolbachia-infected Ae. aegypti.