Association of Viraemic Phase Viral Load, Antibody Responses, and Immune Biomarkers With Severe Dengue.

Severe dengue is influenced by the virus serotype, viral load, host exposure status, immune response, host genetics, and other host factors. The objective of the present study was to identify a panel of prognostic markers for severe dengue during the viraemic phase. We investigated 326 real-time RT-PCR positive dengue cases to find out the association of viral load, antibody titers, and immune status. Plasma levels of 27 cytokines, chemokines, and endothelial cell-related factors were estimated in a subset of 206 patients. Viral load was lower in DENV-3 cases compared to DENV-1 and DENV-2 cases (p < 0.0001). Viral load was lower in secondary infections compared to primary infections, irrespective of serotypes (p < 0.0001). Viral load was not different between dengue patients without warning signs (DWOWS), dengue with warning signs (DWWS), and severe dengue. The total number of cytokines, chemokines, and growth factors produced above the assay detection threshold was higher in severe cases compared to DWOWS and DWWS (p < 0.05). Penalized multivariate regression identified significant associations between dengue serotype and IgM OD ratio, viral load (log₁₀), granulocyte colony-stimulating factor, interferon (IFN)-γ induced protein-10 (IP-10), and macrophage inflammatory protein-1β (MIP-1β) (p < 0.05), with good discrimination between DENV-1 and DENV-2 infections (area under the curve [AUC] = 81.11%). IgA OD ratio, viral load (log₁₀), interleukin-10 (IL-10), MIP-1α, syndecan-1 (SDC-1), and vascular endothelial growth factor-A were significantly associated with immune status, accurately distinguishing primary and secondary infections (AUC = 92.56%). IFN-γ, IL-1β, IL-1RA, IL-2, IL-6, IL-8, IL-10, IL-18, and TPO were significantly elevated in severe dengue cases compared to DWOWS and DWWS (p < 0.05). Exploratory penalized regression results suggested higher odds of the dengue severity with increasing levels of IgA, IgE, G-CSF, GM-CSF, IFN-α, IFN-γ, IL-1β, IL-1RA, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-17A, IL-18, IP-10, MCP-1, resistin, SDC-1, TNF-α, and VEGF-D (OR > 1 per standard deviation increase). To conclude, the present study suggests that a dysregulated immune response, indicated by elevated levels of cytokines, chemokines, and endothelial cell-related factors, occurs in the viraemic phase of severe dengue cases and can be exploited to design a panel of prognostic markers.