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PubMed1997

Identification of two surface proteins from C6/36 cells that bind dengue type 4 virus.

Dengue viruses infect cells by attaching to a surface receptor, probably through the envelope (E) glycoprotein, located on the surface of the viral membrane. However, the identity of the dengue virus receptor in the mosquito and in mammalian host cells remains unknown. To identify and characterize the molecules responsible for binding dengue virus, overlay protein blot and binding assays were performed with labeled virus. Two glycoproteins of 40 and 45 kDa located on the surface of C6/36 cells bound dengue type 4 virus. Virus binding by total and membrane proteins obtained from trypsin-treated cells was inhibited, while neuraminidase treatment did not inhibit binding. Periodate treatment of cell proteins did not reduce virus binding, but it modified the molecular weight of the polypeptide detected by overlay assays. Preincubation of C6/36 cells with electroeluted 40- and 45-kDa proteins or with specific antibodies raised against these proteins inhibited virus binding. These results strongly suggest that the 40- and 45-kDa surface proteins are putative receptors or part of a receptor complex for dengue virus.

Aedes↗
PubMed2003

Replication-defective adenoviral vaccine vector for the induction of immune responses to dengue virus type 2.

A recombinant replication-defective adenovirus vector that can overexpress the ectodomain of the envelope protein of dengue virus type 2 (NGC strain) has been constructed. This virus was immunogenic in mice and elicited dengue virus type 2 specific B- and T-cell responses. Sera from immunized mice contained neutralizing antibodies that could specifically recognize dengue virus type 2 and neutralize its infectivity in vitro, indicating that this approach has the potential to confer protective immunity. In vitro stimulation of splenocytes (from immunized mice) with dengue virus type 2 resulted in a significant proliferative response accompanied by the production of high levels of gamma interferon but did not show significant changes in interleukin-4 levels. This is suggestive of a Th1-like response (considered to be important in the maturation of cytotoxic T lymphocytes that are essential for the elimination of virus-infected cells). The data show that adenovirus vectors offer a promising alternative strategy for the development of dengue virus vaccines.

Adenoviridae↗
PubMed2004

Alterations of pr-M cleavage and virus export in pr-M junction chimeric dengue viruses.

During the export of flavivirus particles through the secretory pathway, a viral envelope glycoprotein, prM, is cleaved by the proprotein convertase furin; this cleavage is required for the subsequent rearrangement of receptor-binding E glycoprotein and for virus infectivity. Similar to many furin substrates, prM in vector-borne flaviviruses contains basic residues at positions P1, P2, and P4 proximal to the cleavage site; in addition, a number of charged residues are found at position P3 and between positions P5 and P13 that are conserved for each flavivirus antigenic complex. The influence of additional charged residues on pr-M cleavage and virus replication was investigated by replacing the 13-amino-acid, cleavage-proximal region of a dengue virus (strain 16681) with those of tick-borne encephalitis virus (TBEV), yellow fever virus (YFV), and Japanese encephalitis virus (JEV) and by comparing the resultant chimeric viruses generated from RNA-transfected mosquito cells. Among the three chimeric viruses, cleavage of prM was enhanced to a larger extent in JEVpr/16681 than in YFVpr/16681 but was slightly reduced in TBEVpr/16681. Unexpectedly, JEVpr/16681 exhibited decreased focus size, reduced peak titer, and depressed replication in C6/36, PS, and Vero cell lines. The reduction of JEVpr/16681 multiplication correlated with delayed export of infectious virions out of infected cells but not with changes in specific infectivity. Binding of JEVpr/16681 to immobilized heparin and the heparin-inhibitable infection of cells were not altered. Thus, diverse pr-M junction-proximal sequences of flaviviruses differentially influence pr-M cleavage when tested in a dengue virus prM background. More importantly, greatly enhanced prM cleavability adversely affects dengue virus export while exerting a minimal effect on infectivity. Because extensive changes of charged residues at the pr-M junction, as in JEVpr/16681, were not observed among a large number of dengue virus isolates, these results provide a possible mechanism by which the sequence conservation of the pr-M junction of dengue virus is maintained in nature.

Amino Acid Sequence↗
PubMed2005

Variable surface epitopes in the crystal structure of dengue virus type 3 envelope glycoprotein.

Dengue virus is an emerging global health threat. The major envelope glycoprotein, E, mediates viral attachment and entry by membrane fusion. Antibodies that bind but fail to neutralize noncognate serotypes enhance infection. We have determined the crystal structure of a soluble fragment of the envelope glycoprotein E from dengue virus type 3. The structure closely resembles those of E proteins from dengue type 2 and tick-borne encephalitis viruses. Serotype-specific neutralization escape mutants in dengue virus E proteins are all located on a surface of domain III, which has been implicated in receptor binding. While antibodies against epitopes in domain I are nonneutralizing in dengue virus, there are neutralizing antibodies that recognize serotype-conserved epitopes in domain II. The mechanism of neutralization for these antibodies is probably inhibition of membrane fusion. Our structure shows that neighboring glycans on the viral surface are spaced widely enough (at least 32 A) that they can interact with multiple carbohydrate recognition domains on oligomeric lectins such as DC-SIGN, ensuring maximum affinity for these putative receptors.

Crystallization↗
PubMed2006

Dengue research and training supported through the World Health Organization.

The rapidly increasing burden of dengue, the varied and often poorly understood factors contributing to its global spread, and the challenges of preventing and controlling it have led to a renewed call for more research and training on the disease. The main aims are to improve vector control, case management, and primary prevention through vaccine development. The World Health Organization (WHO), through its inter-departmental working group on dengue, is actively engaged in supporting and co-ordinating the major research activities. The dengue research initiatives of the Special Programme for Research and Training in Tropical Diseases (TDR), other departments at the WHO's Geneva headquarters, the WHO's regional and country offices, and the organization's dengue-affected member states are summarized in this article. This intensified effort, in close collaboration with other stakeholders, is contributing towards the goals of reversing the current epidemiological trends and of reducing the global burden posed by dengue in all of its forms.

Aedes↗
PubMed2005

Two dimensional VOPBA reveals laminin receptor (LAMR1) interaction with dengue virus serotypes 1, 2 and 3.

BACKGROUND: The search for the dengue virus receptor has generated many candidates often identified only by molecular mass. The wide host range of the viruses in vitro combined with multiple approaches to identifying the receptor(s) has led to the notion that many receptors or attachment proteins may be involved and that the different dengue virus serotypes may utilize different receptors on the same cells as well as on different cell types. RESULTS: In this study we used sequential extraction of PS Clone D cell monolayers with the detergent beta-octylglucopyranoside followed by sodium deoxycholate to prepare a cell membrane-rich fraction. We then used 2 dimensional (2D) gel electrophoresis to separate the membrane proteins and applied a modified virus overlay protein binding assay (VOPBA) to show that dengue virus serotypes 1, 2 and 3 all interact with the 37 kDa/67 kDa laminin receptor (LAMR1), a common non-integrin surface protein on many cell types. CONCLUSION: At least 3 of the 4 dengue serotypes interact with the 37 kDa/67 kDa laminin receptor, LAMR1, which may be a common player in dengue virus-cell surface interaction.

Animals↗
PubMed2006

Enhancement of recombinant soluble dengue virus 2 envelope domain III protein production in Escherichia coli trxB and gor double mutant.

The dengue virus is currently the most important flavivirus causing human diseases in the tropical and subtropical regions of the world. The envelope protein domain III of dengue virus type 2 (D2EIII), which induces protective and neutralizing antibodies, was expressed as an N-terminal fusion to a hexa-histidine tag in Escherichia coli. The expression of recombinant D2EIII of 103 amino acids in the soluble form can be achieved using suitable host strains, such as Origami, at a low induction temperature of 18 degrees C. The enhanced production of the soluble protein could be attributed to the thioredoxin reductase (trxB) and glutathione reductase (gor) double mutations in the Origami genome. The soluble and refolded D2EIII proteins were recognized by different antibodies including human patient antiserum. The immunization of rats with soluble D2EIII protein elicited the production of antibodies that could recognize the D2EIII protein in the D2EIII precursor protein and in C-terminal truncated dengue envelope protein type 1-4. Thus, this protein production system is suitable for the production of authentic recombinant dengue proteins that may be used in the diagnosis of the dengue virus infection or in vaccine development.

Animals↗
PubMed1993

Dengue. Muscle biopsy findings in 15 patients.

Dengue is known to produce a syndrome involving muscles, tendons and joints. The hallmark of this syndrome is severe myalgia but includes fever, cutaneous rash, and headache. The neuromuscular aspects of this infection are outlined only in isolated reports, and the muscle histopathological features during myalgia have not been described. In order to ascertain the actual neuromuscular involvement in dengue and better comprehend the histological nature of myalgia, we performed a clinical and neurological evaluation, a serum CPK level and a muscle biopsy (with histochemistry) in 15 patients (4 males), median age 23 years (range 14-47) with classic dengue fever, serologically confirmed, during the brazilian dengue epidemics from September 1986 to March 1987. All patients had a history of fever, headache and severe myalgia. Upon examination 4 had a cutaneous rash, 3 had fever, and 3 a small hepatomegaly. The neurological examination was unremarkable in all and included a manual muscle test. CPK was mildly elevated in only 3 patients. Muscle biopsy revealed a light to moderate perivascular mononuclear infiltrate in 12 patients and lipid accumulation in 11. Mild mitochondrial proliferation was seen in 3, few central nuclei in 3, rare foci of myonecrosis in 3, and 2 patients had type grouping. Dengue in our patients, produced myalgia but no detectable muscle weakness or other neuromuscular involvement. The main histopathological correlation with myalgia seems to be a perivascular mononuclear infiltrate and lipid accumulation.

Adolescent↗
PubMed2005

[Neurological manifestations of dengue: study of 41 cases].

UNLABELLED: The increase of encephalitis and meningoencephalitis in patients with dengue, diagnosed at a public hospital, Neurology State reference, we adopted systematic data collection. OBJECTIVE: The objective was to present 41 cases of neurological manifestations of dengue and to compare data with literature. METHOD: This is a descriptive study, retrospective from March to July 1997 and, prospective, from February to May 2002, analyzing damaged neurological regions and diagnostic of 41 patients. RESULTS: Involved regions were brain (5/7 cases - 71.4%, in 1997, and 20/34 cases - 58.8%, in 2002), spinal cord (2/34 cases - 5.9% in 2002) and peripheral nerves (2/7 cases - 28.6% in 1997 and 12/34 cases - 35.3% in 2002). There was no meningeal involvement. According to topography, there was encephalic and peripheral nerves diagnosis in both periods and, exclusively in 2002, spinal cord damage. Cerebral hemorrhage and acute disseminated encephalomyelitis were diagnosed for the first time, as well as hemifacial spasm worsening as possible neurological manifestation of dengue. CONCLUSION: This is the third casuistics in dengue and nervous system. Three dengue complications were diagnosed, for the first time registered on the literature.

Brain Diseases↗
PubMed1994

[Dengue in a urban locality of southeastern Brazil: epidemiological aspects].

A dengue fever epidemic which occurred in Ribeirão Preto County, S. Paulo State, Brazil, during the period November, 1990 to March, 1991 has been analysed elsewhere. The general aspects of dengue epidemiology and control have been reviewed in this article. Emphasis is given to the analysis of some factors involved in the risk of dengue haemorrhagic fever and ecological aspects of the vector, as well as to the appropriateness of strategies for dengue eradication or control. Epidemiological characteristics of dengue, mainly those related to its occurrence in different geographical areas and periods of time are described. The Ribeirão Preto epidemic has thus, been set within the context of the spread of the disease at global level, in the Americas, and particularly in Brazil and S. Paulo State.

Brazil↗
PubMed1998

[Geographical distribution of dengue and socioeconomic factors in an urban locality in southeastern Brazil].

INTRODUCTION: The incidence of dengue (serum type I) in the city of S. José do Rio Preto during an epidemic which occurred in the first semester of 1995 is analyzed in terms of geographical areas defined by socioeconomic variables. MATERIAL AND METHOD: The epidemiological method of analysis is the "ecological study" type. To calculate the coefficient of incidence of dengue, all cases both confirmed and reported between January and July, 1995 are considered. The environmental units are defined according to socioeconomic variables based on the IBGE (Brazilian Institute of Geography and Statistics) Census of 1991, through cluster analysis. The linear correlation coefficient between coefficient of incidence and environmental variables is also calculated. RESULTS AND DISCUSSION: Three distinct environmental units are identified and described on the basis of both economic and educational level. The coefficient of incidence of dengue varied in accordance with the environmental unit: in the unit of low standard the coefficient was 2.7 times greater than that of the unit of highest standard, showing that in these units the determining factors of dengue have a differentiating effect. The roles of some of the determining factors such as population density, basic sanitary services and vector density are discussed. The importance of this study for the control of dengue is also emphasized.

Brazil↗
PubMed2006

[Cultural conceptions on dengue in urban contexts in Mexico].

OBJECTIVE: To explore the conceptual dimensions of dengue in the urban context, aiming at creating hypotheses about community attitudes toward prevention campaigns. METHODS: An exploratory cross-sectional study was carried out between March and April 2003 comprising 130 people selected by proposition sampling in three municipalities with different dengue prevalences in Mexico. Semi-structured interviews were applied using free lists, pile sorts and triads. Dengue-related terms and groups of conceptual dimensions were investigated. A consensual analysis was performed by factorizing the major components as well as a dimensional analysis with hierarchical clustering and multidimensional scales. RESULTS: The consensual model showed high homogeneity in dengue conceptions (values of 14.5 and 13.5 in the most prevalent contexts, and 5.4 in the least prevalent one). The common dimensions of conceptions were: preventive measures, symptoms, causes and reservoirs of Aedes aegypti (goodness of fit test values: <0.28). In the three contexts studied, a conception of basic prevention based on public actions by health officials predominated while individual and community actions were almost never mentioned. A moral dimension also appeared in the conception based on a notion of hygiene as a differentiating mechanism between the nearby community (clean) and outside people and communities (dirty and sick). CONCLUSIONS: The cultural conceptions of dengue do not favor self-managed community involvement in vertical prevention campaigns, and create obstacles to modifying community and individual prevention and control practices.

Adult↗
PubMed2006

[Data quality of dengue epidemiological surveillance in Belo Horizonte, Southeastern Brazil].

OBJECTIVE: To evaluate the quality of data from the Brazilian information system for mandatory reporting diseases, for the detection of cases notified as suspected dengue fever and hospitalized in the public and private hospitals associated to the Public Health System. METHODS: The study was carried out in Belo Horizonte, Southeastern Brazil, during the years of 1996 to June 2002. The criterion of evaluation used were those recommended by the Guidelines for Evaluating Public Health Surveillance Systems. As a reference standard, medical charts recorded in the Unified System hospitalized discharge database system were revised and validated. A total of 266 (90%) of 294 medical charts were selected; 230 (86.5%) filled the suspect dengue fever criterion. To verify possible association between underreporting and selected variables, was used the odds ratio, with 95% of confidence interval in a logistic regression model. The sensitivity was defined as the proportion of hospitalized dengue cases registered in both systems. Predictive value positive was calculated as the proportion of confirmed cases and those recorded in the reporting system. RESULTS: Underreporting of suspected dengue fever was of 37% cases during 1997 to 2002, it was five times higher during the first three years (OR=5.93; 95% CI: 2.50-14.04) and eight times higher for patients hospitalized in private hospitals than in the public ones (OR=8.42; 95% CI: 2.26-31.27). Underreport was also associated to cases with no haemorrhagic episodes (OR=2.81; 95% CI: 1.28-6.15) and without dengue-specific laboratory exams in medical charts (OR=4.07; 95% CI:1.00-16.52). Sensitivity was 63% and predictive value positive was 43%. CONCLUSIONS: Cases recorded in the reporting system were those more severe and did not represent the total of cases hospitalized in Unified Health System, thus the case fatality rate may be overestimated. The results indicate the necessity of changes in the evaluated surveillance model and in the implementation of the qualification of the health professionals, mainly those working in the private hospitals associated to Unified Health System.

Adolescent↗
PubMedDate not supplied

[Dengue study in a slum area in Rio de Janeiro: preliminary analysis].

This study is part of a program to control and prevent dengue in a slum bordering on the grounds of the Oswaldo Cruz Foundation in Rio de Janeiro, Brazil. The results obtained from a questionnaire and entomological survey called attention to problems pertaining to the information transmitted by public health campaigns and its interpretation, since many practices result from misunderstanding or forgetting preventive messages. Dengue-related data include most frequent vector breeding sites, people's knowledge, and dengue-related habits. The study's conclusions in terms of dengue prevention point to the need for drafting messages not only about ideal preventive practices but also teaching possible solutions: disseminating frequent messages throughout the year and not only seasonally and planning health education to join health professionals and the population in the search for sustainable dengue control alternatives.

Aedes↗
PubMedDate not supplied

[Critical aspects of dengue control in Brazil].

Dengue is now the main reemerging disease in the world. In the absence of an efficacious preventive vaccine and effective etiologic treatment and chemoprophylaxis, the only vulnerable link for reducing dengue transmission is the mosquito Aedes aegypti, its principal vector. There are many difficulties in combating this mosquito in large and medium-sized cities. The complexity of contemporary urban life generates factors that facilitate the mosquito's proliferation and constraints on the reduction of its infestation rates. The objectives of dengue control should be based on available scientific and technical knowledge. Thus, while it is not possible to avoid dengue in areas infested with A. aegypti, it is possible to prevent major epidemics by improving epidemiological surveillance, and it is both possible and feasible to reduce the disease's case fatality from the current 5 to 6% to some 1% in the severe forms. The elaboration and execution of strategic plans for the organization of medical care for suspected dengue cases have proven to be a highly useful instrument to reduce case fatality both in other countries and in some cities of Brazil.

Aedes↗
PubMed2004

[Dengue prevention and control: a review of studies on knowledge, beliefs, and practices].

This article aims to contribute to dengue control programs through a review of recent studies on knowledge, beliefs, and practices concerning dengue and dengue prevention. The results show that adequate knowledge of dengue and prevention methods are found in close association with high rates of domiciliary infestation by Aedes aegypti. This suggests that traditional education strategies, although efficient in transmitting information, have failed to change population behavior. Qualitative studies reveal two important issues that appear to explain these attitudes: representations of dengue and risks associated with mosquitoes and difficulties in avoiding infestation of household water recipients due to sanitation problems in communities.

Aedes↗
PubMed2006

[Dengue control in an urban area of Brazil: impact of the Family Health Program on traditional control].

A study was performed in different areas of São José do Rio Preto which include the Family Health Program (FHP) and the Dengue Control Program, and the results of integration between the two programs were evaluated. In addition to other responsibilities, community health agents instructed residents on dengue control measures, encouraging the population to adopt the practices in areas with the FHP. Vector control agents were responsible for breeding site control and instructed local residents on the Dengue Control Program. From 2001 to 2003, surveys were conducted to measure residents' dengue control knowledge and practices. The proportions of residents in the FHP area that reported health services as a source of information increased significantly as compared to the other area. There were significant changes concerning the increase in information about the disease and reduction in vector breeding sites. The results show that integration between the programs is possible and could help optimize resources, avoiding duplicity of procedures and fostering greater community involvement in dengue control.

Aedes↗
PubMed2001

[Popular notions regarding "dengue" and "rompehuesos", 2 models of the disease in Colombia].

OBJECTIVE: To deliver, through children, educational messages to families in Neiva, the capital city of the department of Huila, in Colombia. METHODS: An educational project was developed to include, in schoolchildren's natural sciences and environmental education curriculum, basic education on dengue, its vector, and its control. Through surveys and Likert scales, the knowledge and attitudes in the schoolchildren's homes were determined. This was complemented with open-ended interviews that reflected cultural aspects in the area of health and how dengue disease is a part of people's lives. Before and after the intervention, larval infestation indices were determined for the schoolchildren's homes. RESULTS: A cultural pattern was found for the disease that differentiated between rompehuesos (breakbone fever) and "dengue". Rompehuesos corresponds, in popular terms, to classical dengue, a disease that can be dealt with using family and community resources. Institutional medicine, by means of its health agencies and health workers, as well as the communications media, has managed to superimpose another model: that which is associated with dengue hemorrhagic fever. DISCUSSION: Alternatives are considered for prevention efforts that would be sufficient for the conditions in which the vector's cycle occurs in Neiva. Also presented are the community's disease model and the survey results. Together, these elements can guide the formulation and development of educational efforts.

Child↗