Isotope Coded Protein Labeling analysis of plasma specimens from acute severe dengue fever patients

Serum ferritin level as a prognostic biomarker for predicting dengue disease severity: A systematic review and meta-analysis

Serum ferritin levels serves as biomarkers in many inflammatory and infectious diseases. This current systematic review and meta-analysis evaluated whether serum ferritin levels are associated with severe dengue and its utility as a biomarker of disease severity. Literature searches were conducted in PubMed, Scopus, ScienceDirect, the Cochrane library, and Google Scholar. A total of 18 studies examining the serum ferritin levels in dengue cases in the context of disease severity (nine studies having dengue classification as non-severe vs. severe dengue cases, and nine studies having dengue classification as dengue without warning signs (DwoWS), dengue with warning signs (DwWS), and severe dengue cases) were included and the quality of the studies was assessed using the Quality in Prognostic Factor Studies tool. The meta-analysis was performed using STATA software to calculate the effect size as a standardized mean difference (SMD) or Hedges 'g' for the continuous outcome. Higher serum ferritin levels were found in severe dengue cases compared to non-severe cases [SMD (Hedges 'g') 4.05 (95% C.I. 2.09-6.00), (I2  = 98.8%)]. In the second group, DwWS cases showed high serum ferritin levels compared to DwoWS [SMD 2.01 (95% C.I. 0.92-3.10), (I2  = 97.89%)], and severe dengue cases showed higher levels of serum ferritin compared to DwWS [SMD 2.66 (95% C.I. 1.72-4.48), (I2  = 98.78%)] and DwoWS cases [SMD 6.65 (95% C.I. 1.72-11.59), (I2  = 99.78%]. Subgroup analysis for the country of study (India vs. others), ferritin testing methods, and ferritin measurement day revealed testing method as a significant contributor to heterogeneity. To conclude, the present study suggests serum ferritin as a prognostic marker for dengue disease severity. Multi-centric studies involving a large number of dengue patients with a uniform case definition accounting for all the confounding variables might help in determining a universal cut-off value to discriminate between non-severe and severe dengue.

Proteomics of Select Neglected Tropical Diseases

Technological advances in mass spectrometry have enabled the extensive identification, characterization, and quantification of proteins in any biological system. In disease processes proteins are often altered in response to external stimuli; therefore, proteomics, the large-scale study of proteins and their functions, represents an invaluable tool for understanding the molecular basis of disease. This review highlights the use of mass spectrometry-based proteomics to study the pathogenesis, etiology, and pathology of several neglected tropical diseases (NTDs), a diverse group of disabling diseases primarily associated with poverty in tropical and subtropical regions of the world. While numerous NTDs have been the subject of proteomic studies, this review focuses on Buruli ulcer, dengue, leishmaniasis, and snakebite envenoming. The proteomic studies highlighted provide substantial information on the pathogenic mechanisms driving these diseases; they also identify molecular targets for drug discovery and development and uncover promising biomarkers that can assist in early diagnosis.

Vitamin D serostatus and dengue fever progression to dengue hemorrhagic fever/dengue shock syndrome

Vitamin D could modulate pathways leading to dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). We examined the associations of serum total 25-hydroxy vitamin D [25(OH)D] and vitamin D binding protein (VDBP) concentrations in patients with uncomplicated dengue fever (DF) with risk of progression to DHF/DSS. In a case–control study nested in a cohort of DF patients who were followed during the acute episode in Bucaramanga, Colombia, we compared 25(OH)D and VDBP at onset of fever between 110 cases who progressed to DHF/DSS and 235 DF controls who did not progress. 25(OH)D concentrations were also compared between the acute sample and a sample collected >1 year post-convalescence in a subgroup. Compared with 25(OH)D ⩾75 nmol/l, adjusted odds ratios (95% CI) for progression were 0·44 (0·22–0·88) and 0·13 (0·02–1·05) for 50 to 75 nmol/l (vitamin D insufficiency) and <50 nmol/l (vitamin D deficiency), respectively (P, trend = 0·003). Mean 25(OH)D concentrations were much lower post-convalescence compared with the acute episode, regardless of case status. Compared with controls, mean VDBP was non-significantly lower in cases. We conclude that low serum 25(OH)D concentrations in DF patients predict decreased odds of progression to DHF/DSS.

Differential proteomic analysis of virus-enriched fractions obtained from plasma pools of patients with dengue fever or severe dengue

Background

Dengue is the most widespread mosquito-borne viral disease of public health concern. In some patients, endothelial cell and platelet dysfunction lead to life-threatening hemorrhagic dengue fever or dengue shock syndrome. Prognostication of disease severity is urgently required to improve patient management. The pathogenesis of severe dengue has not been fully elucidated, and the role of host proteins associated with viral particles has received little exploration.

Methods

The proteomes of virion-enriched fractions purified from plasma pools of patients with dengue fever or severe dengue were compared. Virions were purified by ultracentrifugation combined with a water-insoluble polyelectrolyte-based technique. Following in-gel hydrolysis, peptides were analyzed by nano-liquid chromatography coupled to ion trap mass spectrometry and identified using data libraries.

Results

Both dengue fever and severe dengue viral-enriched fractions contained identifiable viral envelope proteins and host cellular proteins. Canonical pathway analysis revealed the identified host proteins are mainly involved in the coagulation cascade, complement pathway or acute phase response signaling pathway. Some host proteins were over- or under-represented in plasma from patients with severe dengue compared to patients with dengue fever. ELISAs were used to validate differential expression of a selection of identified host proteins in individual plasma samples of patients with dengue fever compared to patients with severe dengue. Among 22 host proteins tested, two could differentiate between dengue fever and severe dengue in two independent cohorts (olfactomedin-4: area under the curve (AUC), 0.958; and platelet factor-4: AUC, 0.836).

Conclusion

A novel technique of virion-enrichment from plasma has allowed to identify two host proteins that have prognostic value for classifying patients with acute dengue who are more likely to develop a severe dengue. The impact of these host proteins on pathogenicity and disease outcome are discussed.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1271-7) contains supplementary material, which is available to authorized users.

Novel interactions of domain III from the envelope glycoprotein of dengue 2 virus with human plasma proteins

Blood cells and plasma are important media for the four serotypes of dengue virus (DENV1-4) spreading into an infected person. Thus, interactions with human plasma proteins are expected to be decisive in the course of the viral infection. Affinity purification followed by MS analysis (AP/MS) was used to isolate and identify plasma-derived proteins capable to interact with a recombinant protein comprising the domain III of the envelope protein of DENV2 (DIIIE2). The elution of the AP potently inhibits DENV2 infection. Twenty-nine proteins were identified using a label-free approach as specifically captured by DIIIE2. Of these, a direct interaction with C reactive protein, thrombin and Inter-alpha-inhibitor complexes was confirmed by ELISA. Results provide further evidence of a significant representation of proteins from complement and coagulation cascades on DENV2 interactome in human plasma and stand out the domain III of the viral envelope protein as participant on these interactions. A functional clustering analysis highlights the presence of three structural motifs among putative DIIIE2-binding proteins: hydroxylation and EGF-like calcium-binding- and Gla domains.

BIOLOGICAL SIGNIFICANCE

Early cycles of dengue virus replication take place in human blood cells. Thus, the characterization of the interactome of dengue virus proteins in human plasma can lead to the identification of pivotal interactions for the infection that can eventually constitute the target for the development of methods to control dengue virus-caused disease. In this work we identified 29 proteins from human plasma that potentially interact with the envelope protein of dengue 2 virus either directly or through co-complex formation. C reactive protein, thrombin and Inter-alpha-inhibitor complexes were validated as interactors of the domain III of the envelope protein of dengue 2. Results highlight the presence of three structural motifs among putative DIIIE2-binding proteins: hydroxylation and EGF-like calcium-binding- and Gla domains. This finding together with the participation of domain III of the envelope protein on the interactions with human plasma proteins should contribute to a better understanding of dengue virus interactome in human plasma. Such knowledge can contribute to the development of more effective treatments to infected persons.

Dengue

Dengue viruses have spread rapidly within countries and across regions in the past few decades, resulting in an increased frequency of epidemics and severe dengue disease, hyperendemicity of multiple dengue virus serotypes in many tropical countries, and autochthonous transmission in Europe and the USA. Today, dengue is regarded as the most prevalent and rapidly spreading mosquito-borne viral disease of human beings. Importantly, the past decade has also seen an upsurge in research on dengue virology, pathogenesis, and immunology and in development of antivirals, vaccines, and new vector-control strategies that can positively impact dengue control and prevention.

Molecular classification of outcomes from dengue virus -3 infections

OBJECTIVES

Dengue virus (DENV) infection is a significant risk to over a third of the human population that causes a wide spectrum of illness, ranging from sub-clinical disease to intermediate syndrome of vascular complications called dengue fever complicated (DFC) and severe, dengue hemorrhagic fever (DHF). Methods for discriminating outcomes will impact clinical trials and understanding disease pathophysiology.

STUDY DESIGN

We integrated a proteomics discovery pipeline with a heuristics approach to develop a molecular classifier to identify an intermediate phenotype of DENV-3 infectious outcome.

RESULTS

121 differentially expressed proteins were identified in plasma from DHF vs dengue fever (DF), and informative candidates were selected using nonparametric statistics. These were combined with markers that measure complement activation, acute phase response, cellular leak, granulocyte differentiation and viral load. From this, we applied quantitative proteomics to select a 15 member panel of proteins that accurately predicted DF, DHF, and DFC using a random forest classifier. The classifier primarily relied on acute phase (A2M), complement (CFD), platelet counts and cellular leak (TPM4) to produce an 86% accuracy of prediction with an area under the receiver operating curve of >0.9 for DHF and DFC vs DF.

CONCLUSIONS

Integrating discovery and heuristic approaches to sample distinct pathophysiological processes is a powerful approach in infectious disease. Early detection of intermediate outcomes of DENV-3 will speed clinical trials evaluating vaccines or drug interventions.

Receptor-activated human α2-macroglobulin interacts with the envelope protein of dengue virus and protects virions from temperature-induced inactivation through multivalent binding

Based on the hypothesis that interactions between virions and serum components may influence the outcome of dengue virus (DENV) infections, we decided to use affinity chromatography with domain III from the envelope (E) protein of DENV2 (DIIIE2) as a ligand to isolate virus-binding proteins from human plasma. This approach yielded serum amyloid P (SAP) and α2-macroglobulin (α2M) as novel viral interactors. After confirming the specific binding of both SAP and α2M to DIIIE2 by ELISA, the latter interaction was examined in greater detail. We obtain evidence suggesting that the binding species was actually the receptor-activated form of α2M (α2M*), that α2M* could bind monovalently to recombinant domain III from all four DENV serotypes with affinities in the micromolar range ranking as DENV4>DENV1~DENV2>DENV3 and that this interaction exhibited a strong avidity effect when multivalent binding was favoured (KD 8 × 10(-8) M for DIIIE2). We also showed that α2M* bound to DENV virions of the four serotypes, protecting the virus from temperature-induced inactivation in the absence of serum and enhancing infectivity. The latter effect exhibited an ED50 of 2.9 × 10(-8) M, also suggesting an avidity effect due to multivalent binding. These results will further contribute to the characterization of the virus-host factor interaction network during human DENV infection.

Differential expression of serum/plasma proteins in various infectious diseases: specific or nonspecific signatures

Apart from direct detection of the infecting organisms or biomarker of the pathogen itself, surrogate host markers are also useful for sensitive and early diagnosis of pathogenic infections. Early detection of pathogenic infections, discrimination among closely related diseases with overlapping clinical manifestations, and monitoring of disease progression can be achieved by analyzing blood biomarkers. Therefore, over the last decade large numbers of proteomics studies have been conducted to identify differentially expressed human serum/plasma proteins in different infectious diseases with the intent of discovering novel potential diagnostic/prognostic biomarkers. However, in-depth review of the literature indicates that many reported biomarkers are altered in the same way in multiple infectious diseases, regardless of the type of infection. This might be a consequence of generic acute phase reactions, while the uniquely modulated candidates in different pathogenic infections could be indicators of some specific responses. In this review article, we will provide a comprehensive analysis of differentially expressed serum/plasma proteins in various infectious diseases and categorize the protein markers associated with generic or specific responses. The challenges associated with the discovery, validation, and translational phases of serum/plasma biomarker establishment are also discussed.