Ceramides as a lipid shield in dengue virus infection
Category: Research Poster
Author(s): Kylee Pham, Suad Elmegerhi, Shashmeera Shriganeshan, Paul Soma, Skylar Gregersen
Presenter(s): Kylee Pham
Mentors(s): Rushika Perera
Dengue viruses (DENVs) are flaviviruses responsible for ~400 million infections each year across more than 100 countries in tropical and subtropical regions. We have previously demonstrated that DENVs exploit host sphingolipid metabolism throughout their life cycle to promote replication. Among sphingolipids, ceramides serve as the central metabolic hub. Ceramides are synthesized in the endoplasmic reticulum by ceramide synthases (CerS), which catalyze the addition of a fatty acyl group to a sphingoid base. Lipidomic analyses revealed that ceramide levels increase over the course of DENV infection in human liver cells (Huh7), suggesting a potential role for ceramides in viral replication. Therefore, we hypothesized that ceramides are required for virus replication. To test this, we inhibited ceramide synthesis in Huh7 cells using Fumonisin B1 (FB1). FB1 treatment led to an accumulation of intracellular virus particles between 24 and 48 hours post-infection (hpi), followed by a pronounced release into the supernatant. This “purge” correlated with extracellular titers that rose ~2.5-fold between 48 and 72 hpi compared to untreated controls. These findings indicated that the reduction in ceramide levels created a cellular environment beneficial for DENV2 replication. Strikingly, supplementation with exogenous ceramides resulted in a 4.5-log reduction in viral titer. Moreover, siRNA-mediated knockdown of CerS1 and CerS2 increased infectious DENV2 titers, indicating that ceramides exert an antiviral—rather than proviral—effect during infection. Together, these findings reveal that ceramides play a critical role in restricting the DENV life cycle in Huh7 cells.