Dengue virus NS1 protein activates cells via Toll-like receptor 4 and disrupts endothelial cell monolayer integrity.

Complications arising from dengue virus infection include potentially fatal vascular leak, and severe disease has been linked with excessive immune cell activation. An understanding of the triggers of this activation is critical for the development of appropriately targeted disease control strategies. We show here that the secreted form of the dengue virus nonstructural protein 1 (NS1) is a pathogen-associated molecular pattern (PAMP).