Best practices in dengue surveillance: a report from the Asia-Pacific and Americas Dengue Prevention Boards

Background

Dengue fever is a virus infection that is spread by the Aedes aegypti mosquito and can cause severe disease especially in children. Dengue fever is a major problem in tropical and sub-tropical regions of the world.

Methodology/Principal Findings

We invited dengue experts from around the world to attend meetings to discuss dengue surveillance. We reviewed literature, heard detailed reports on surveillance programs, and shared expert opinions.

Results

Presentations by 22 countries were heard during the 2.5 day meetings. We describe the best methods of surveillance in general, the stakeholders in dengue surveillance, and the steps from mosquito bite to reporting of a dengue case to explore how best to carry out dengue surveillance. We also provide details and a comparison of the dengue surveillance programs by the presenting countries.

Conclusions/Significance

The experts provided recommendations for achieving the best possible data from dengue surveillance accepting the realities of the real world (e.g., limited funding and staff). Their recommendations included: (1) Every dengue endemic country should make reporting of dengue cases to the government mandatory; (2) electronic reporting systems should be developed and used; (3) at minimum dengue surveillance data should include incidence, hospitalization rates, deaths by age group; (4) additional studies should be completed to check the sensitivity of the system; (5) laboratories should share expertise and data; (6) tests that identify dengue virus should be used in patients with fever for four days or less and antibody tests should be used after day 4 to diagnose dengue; and (7) early detection and prediction of dengue outbreaks should be goals for national surveillance systems.     

Integrated management and visualization of electronic tag data with Tagbase

Electronic tags have been used widely for more than a decade in studies of diverse marine species. However, despite significant investment in tagging programs and hardware, data management aspects have received insufficient attention, leaving researchers without a comprehensive toolset to manage their data easily. The growing volume of these data holdings, the large diversity of tag types and data formats, and the general lack of data management resources are not only complicating integration and synthesis of electronic tagging data in support of resource management applications but potentially threatening the integrity and longer-term access to these valuable datasets. To address this critical gap, Tagbase has been developed as a well-rounded, yet accessible data management solution for electronic tagging applications. It is based on a unified relational model that accommodates a suite of manufacturer tag data formats in addition to deployment metadata and reprocessed geopositions. Tagbase includes an integrated set of tools for importing tag datasets into the system effortlessly, and provides reporting utilities to interactively view standard outputs in graphical and tabular form. Data from the system can also be easily exported or dynamically coupled to GIS and other analysis packages. Tagbase is scalable and has been ported to a range of database management systems to support the needs of the tagging community, from individual investigators to large scale tagging programs. Tagbase represents a mature initiative with users at several institutions involved in marine electronic tagging research.     

A Prognostic Model for Development of Profound Shock among Children Presenting with Dengue Shock Syndrome

PurposeTo identify risk factors and develop a prediction model for the development of profound and recurrent shock amongst children presenting with dengue shock syndrome (DSS)MethodsWe analyzed data from a prospective cohort of children with DSS recruited at the Paediatric Intensive Care Unit of the Hospital for Tropical Disease in Ho Chi Minh City, Vietnam. The primary endpoint was “profound DSS”, defined as ≥2 recurrent shock episodes (for subjects presenting in compensated shock), or ≥1 recurrent shock episodes (for subjects presenting initially with decompensated/hypotensive shock), and/or requirement for inotropic support. Recurrent shock was evaluated as a secondary endpoint. Risk factors were pre-defined clinical and laboratory variables collected at the time of presentation with shock. Prognostic model development was based on logistic regression and compared to several alternative approaches.ResultsThe analysis population included 1207 children of whom 222 (18%) progressed to “profound DSS” and 433 (36%) had recurrent shock. Independent risk factors for both endpoints included younger age, earlier presentation, higher pulse rate, higher temperature, higher haematocrit and, for females, worse hemodynamic status at presentation. The final prognostic model for “profound DSS” showed acceptable discrimination (AUC=0.69 for internal validation) and calibration and is presented as a simple score-chart.ConclusionsSeveral risk factors for development of profound or recurrent shock among children presenting with DSS were identified. The score-chart derived from the prognostic models should improve triage and management of children presenting with DSS in dengue-endemic areas.     

Fruit and Vegetable Consumption and Cardiovascular Risk Factors in Older Chinese: The Guangzhou Biobank Cohort Study

Objective

To examine the adjusted associations of fruit consumption and vegetable consumption with the Framingham score and its components in the non-Western setting of Southern China, considering health status.

Method

Linear regression was used to assess the cross-sectional associations of fruit and vegetable consumption with the Framingham score and its components, among 19,518 older Chinese (≥50 years) from the Guangzhou Biobank Cohort Study in Southern China (2003–2006), and whether these differed by health status.

Results

The association of fruit consumption with the Framingham score varied by health status (P-value<0.001), but not vegetable consumption (P-value 0.51). Fruit consumption was associated with a lower Framingham score (-0.04 per portions/day, 95% confidence interval (CI) -0.08 to -0.004) among participants in poor health, adjusted for age, sex, recruitment phase, socio-economic position and lifestyle. However, similarly adjusted, fruit consumption was associated with a higher Framingham score (0.05, 95% CI 0.02 to 0.09) among participants in good health, perhaps due to a positive association of fruit consumption with fasting glucose. Similarly adjusted, vegetable consumption was associated with a higher Framingham score (0.03, 95% CI 0.01 to 0.05) among all participants, with no difference by health status.

Conclusion

This large study from a non-western setting found that fruit and vegetable consumption was barely associated with the Framingham score, or major CVD risk factors.     

High-resolution crystal structure of HA33 of botulinum neurotoxin type B progenitor toxin complex

Botulinum neurotoxins (BoNTs) are produced as progenitor toxin complexes (PTCs) by Clostridium botulinum. The PTCs are composed of BoNT and non-toxic neurotoxin-associated proteins (NAPs), which serve to protect and deliver BoNT through the gastrointestinal tract in food borne botulism. HA33 is a key NAP component that specifically recognizes host carbohydrates and helps enrich PTC on the intestinal lumen preceding its transport across the epithelial barriers. Here, we report the crystal structure of HA33 of type B PTC (HA33/B) in complex with lactose at 1.46 Å resolution. The structural comparisons among HA33 of serotypes A–D reveal two different HA33–glycan interaction modes. The glycan-binding pockets on HA33/A and B are more suitable to recognize galactose-containing glycans in comparison to the equivalent sites on HA33/C and D. On the contrary, HA33/C and D could potentially recognize Neu5Ac as an independent receptor, whereas HA33/A and B do not. These findings indicate that the different oral toxicity and host susceptibility observed among different BoNT serotypes could be partly determined by the serotype-specific interaction between HA33 and host carbohydrate receptors. Furthermore, we have identified a key structural water molecule that mediates the HA33/B–lactose interactions. It provides the structural basis for development of new receptor-mimicking compounds, which have enhanced binding affinity with HA33 through their water-displacing moiety.     

The RNA binding protein Larp1 regulates cell division,apoptosis and cell migration

The RNA binding protein Larp1 was originally shown to be involved in spermatogenesis, embryogenesis and cell-cycle progression in Drosophila. Our data show that mammalian Larp1 is found in a complex with poly A binding protein and eukaryote initiation factor 4E and is associated with 60S and 80S ribosomal subunits. A reduction in Larp1 expression by siRNA inhibits global protein synthesis rates and results in mitotic arrest and delayed cell migration. Consistent with these data we show that Larp1 protein is present at the leading edge of migrating cells and interacts directly with cytoskeletal components. Taken together, these data suggest a role for Larp1 in facilitating the synthesis of proteins required for cellular remodelling and migration.     

Synthesis,characterization and preliminary analysis of in vivo biological activity of chitosan/celecoxib microcapsules

The use of chitosan as the wall of microcapsule designed for delivery of encapsulated celecoxib is reported. Microcapsules were characterised with respect to size and encapsulation efficiency of celecoxib. In vivo animals demonstrated that both free celecoxib administration and chitosan/celecoxib microcapsules administration lead to a significant inhibition of cyclooxygenase-2 protein expression in the hepatocytes when compared with vehicle control mice. Interestingly, microcapsule containing celecoxib showed a better inhibition of cyclooxygenase-2 protein expression when compared with a simple oral administration of free celecoxib. Gas-chromatography–mass-spectrometry analysis showed that in mice treated with free celecoxib or chitosan/celecoxib microcapsules, their plasma concentration of celecoxib was similar. Microcapsules-based biomaterials as oral drug delivery vehicles may help to improve the absorption efficiency of therapeutic drugs.     

JC virus-induced Progressive Multifocal Leukoencephalopathy

Progressive multifocal encephalopathy (PML) is a fatal demyelinating disease of the central nervous system (CNS), caused by the lytic infection of oligodendrocytes by a human polyomavirus, JC virus (JCV). PML is rare disease but mostly develops in patients with underlying immunosuppressive conditions, including Hodgkin's lymphoma, lymphoproliferative diseases, in those undergoing antineoplastic therapy and AIDS. However, consistent with the occurrence of PML under immunocompromised conditions, this disease seems to be also steadily increasing among autoimmune disease patients (multiple sclerosis and Crohn's disease), who are treated with antibody-based regimens (natalizumab, efalizumab and rituximab). This unexpected occurrence of the disease among such a patient population reconfirms the existence of a strong link between the underlying immunosuppressive conditions and development of PML. These recent observations have generated a new interest among investigators to further examine the unique biology of JCV.     

Biochemical Characterization of the Cell-Biomaterial Interface by Quantitative Proteomics

Surface topography and texture of cell culture substrata can affect the differentiation and growth of adherent cells. The biochemical basis of the transduction of the physical and mechanical signals to cellular responses is not well understood. The lack of a systematic characterization of cell-biomaterial interaction is the major bottleneck. This study demonstrated the use of a novel subcellular fractionation method combined with quantitative MS-based proteomics to enable the robust and high-throughput analysis of proteins at the adherence interface of Madin-Darby canine kidney cells. This method revealed the enrichment of extracellular matrix proteins and membrane and stress fibers proteins at the adherence surface, whereas it shows depletion of extracellular matrix belonging to the cytoplasmic, nucleus, and lateral and apical membranes. The asymmetric distribution of proteins between apical and adherence sides was also profiled. Apart from classical proteins with clear involvement in cell-material interactions, proteins previously not known to be involved in cell attachment were also discovered.The growth and differentiation of cells in multicellular organisms are regulated by the complex interplay of biochemical and mechanical signals. In the past decades, a plethora of data on the roles of mechanical and structural cues in modulating cellular behaviors has emerged (1–5). It is increasingly evident that cell fates can be changed by engineering the physical properties of the microenvironment to which the cells are exposed (6–8). These observations have inspired the development of functionalized biomaterials that can directly and specifically interact with tissue components, and support or even direct the appropriate cellular activities (9, 10). Although promising progress has been observed in the past few years, several gaps in knowledge in this field have hindered the development of such ”intelligent” biomaterials. In particular, the understanding of the mechanism in which the cell orchestrates physiological and morphological changes by translating mechanical and structural information into biochemical signals is still very limited.As a standard experimental model, cell lines cultured in vitro as a monolayer over solid substrata are usually used to study the effects of biomaterial surfaces on cellular phenotypes. With this simple model system, ingenious experiments have shown that physical forces applied through the extracellular matrix (ECM)1 can induce changes in cell adhesion molecules and stress-induced ion channels, which then lead to changes in the cytoskeleton and gene expressions (11–13). We term the biochemical structure present at the interface between the substratum and the cellular interior the adherence surface (AS), which is composed of the basal plasma membrane with associated structures such as the ECM on one side and the focal adherence complexes on the other. In monolayer cell culture systems, the AS is the only part of the cells in direct contact with the substratum, and is therefore responsible for the first line of communication between the cells and the biomaterial. It is likely that the AS is the organelle that mediates the communication of mechanical and tectonic signals from the substratum to biochemical transducers in the cells. Given the complexity of this process, it is clear that the understanding of this phenomenon cannot be achieved merely by studying individual biological parts in isolation. It is necessary, therefore, to systematically characterize the biochemical factors that mediate the interactions between cells and materials to yield insights into intracellular signaling processes that are responsible for such cellular responses. Toward this goal, we seek to investigate the biochemical basis of how different biomaterials may impose changes in the composition of the AS of adherent cells.MS-based proteomics have recently emerged as a standard technique in modern cell biology. Various techniques based on the chemical conjugation of isotopically labeled reporters to proteins or peptides, such as the isobaric tag for relative and absolute quantitation (iTRAQ) and the isotope-coded affinity tags, enable MS-based proteomics to quantify and compare proteome changes between biological samples. As an attractive alternative, stable isotope labeling with amino acids in cell culture (SILAC) is a metabolic labeling technique that enables isotopically encoded cells to be mixed before lysis and fractionation, thus eliminating inherent quantification biases in these steps, and also enables a simpler procedure and more accurate quantitation (14). SILAC MS-based proteomics have recently contributed to organellar proteomes (15, 16), accurate measurement of protein-protein interactions (17), and the characterization of proteome dynamics during cell differentiation (18). The use of MS-based proteomics has enabled the systematic evaluation of proteome changes on the adhesion of cells to substrata of interest. Kantawong et al. (19) applied DIGE and LC-MS/MS to identify proteome changes in cells on surface with nanotopography. Xu et al. (20) investigated proteome differences of human osteoblasts on various nano-sized hydroxyapatite powders with different shapes and chemical compositions using iTRAQ-based two-dimensional LC-MS/MS.One advantage of proteomics is that it can effectively be combined with subcellular fractionation and allow the comprehensive characterization of the proteins enriched in targeted cellular structures. To yield new insight in molecular interactions in cell-biomaterial interfaces, we aimed to develop a robust protocol for the proteomic characterization of the AS of adherent cells on a biomaterial surface and use it for discovering new cell-biomaterial interface specific biomarkers. Our approach was to develop an isolation technique for AS with high yields and purity for proteomic analysis. The isolated AS on substratum was analyzed by confocal microscopy and Western blotting. SILAC was then used to characterize the fold-enrichment of proteins in the purified AS compared with whole cells and to discover new biomolecules in the cell-biomaterial interface. This study introduces a novel cell-biomaterial interface proteomic procedure, which can be used to identify the AS specific proteome in a high throughput manner and provide a simple and robust method to systematically analyze cell-biomaterial interactions at a molecular level.