Early biomarkers for plasma leakage in dengue infection

Dengue virus infection is among the most prevalent RNA virus infections globally, and imposes a significant burden on affected populations and healthcare systems. This thesis aimed to identify early circulating biomarkers predicting later adverse outcomes, primarily plasma leakage—a critical event preceding severe dengue that typically develops 5-7 days after fever onset in a significant minority of patients. A systematic review and meta-analysis identified 37 studies (n=5925 patients) reporting several biomarkers associated with WHO-defined 'dengue haemorrhagic fever' (elevated C-reactive protein, aspartate aminotransferase, interleukin-8, and decreased albumin) and 'severe dengue' (elevated vascular cell adhesion protein-1, syndecan-1, aspartate aminotransferase, and C-reactive protein), with only scant evidence for plasma leakage as a specific outcome. A case-control study analysed plasma samples collected within 96 hours of onset from 228 patients (114 with plasma leakage) from the Colombo Dengue Study. A multiplex immunoassay (34-plex) revealed elevated levels of vascular cell adhesion molecule-1 and interleukin-33 receptor associated with increased plasma leakage risk, while eotaxin-1 showed protective effects. After adjusting for prior dengue exposure, C-X-C motif chemokine 11 and serum amyloid A also demonstrated significant risk associations. An exploratory proteomics approach used liquid chromatography mass spectrometry (LC-MS/MS) with aptamer-based SomaScan® validation. The analysis identified 107 differentially expressed proteins found in LC-MS/MS and 3,181 via SomaScan, with 23 proteins validated across both platforms. Pathway and functional analysis revealed enrichment in STAT1/STAT3 signalling, antiviral defence mechanisms, T-cell differentiation, and regulation of extracellular matrix components critical to vascular integrity. Key proteins included interferon-stimulated gene 15, heat shock protein HSP90-beta, collagen type III alpha-1 chain, hyaluronan and proteoglycan link protein 3, and interleukin enhancer-binding factor 3. These findings suggest dengue-associated plasma leakage involves coordinated inflammatory signalling, extracellular matrix alterations, and antiviral defence mechanisms beginning in early infection. The biomarkers hold potential for novel prognostic assays for early risk stratification in resource-limited settings.