THE ROLE OF DENGUE VIRUS NON-STRUCTURAL PROTEIN 1 IN DISEASE PATHOGENESIS

Abstract

Dengue virus (DENV) causes an estimated 390 million infections worldwide annually, with severe forms of disease marked by vascular leakage and an over reactive inflammatory response. Endothelial cells (EC) are directly responsible for vascular homeostasis and are highly responsive to circulating mediators but are not commonly infected. Mast cells (MC) are potent cells of the innate immune system that play an important role in EC biology and inflammatory responses. DENV encodes 10 proteins; with only one, the non-structural protein 1 (NS1), secreted from infected cells and accumulating in the blood of patients.NS1 has been implicated in the pathogenesis of vascular permeability, but the mechanism is not completely understood. Using a complementary array of in vitroassays and disease relevant ECs and MCs, we described the possible roles for NS1 in dengue disease pathogenesis. Using microscopy and immunoblotting we observed that ECs internalize NS1 into endosomes, where it accumulates and is degraded overtime. Transcriptome and pathway analysis defined changes in global gene expression in ECs that are associated with cell dysfunction. We observed that NS1 induced an increase in multicellular rearrangements and a decrease in barrier function in ECs. We demonstrated that NS1-dependent activation of the p38 MAPK pathway controls the changes in EC permeability in vitro. Further, we discovered iiithat ECs and MCs respond to NS1 by secreting a specific array of proinflammatory cytokines and chemokines that may contribute to the cytokine storm in dengue disease. Finally, we found that NS1 internalization can mediate the uptake of bound antibodies into ECs. Together, these results suggest a vasoactive and proinflammatory role for DENV NS1 that may participate in the development of severe symptoms in dengue disease. The observed functions of NS1 could lead to the discovery of new therapeutic targets in dengue disease.