Based on the 14 C-acetate labeling studies above, the CE fraction showed an increased amount of newly synthesized lipids (compared to the 16K fraction at the 36 hr time point). In lipid biosynthesis pathways, acetate is a precursor to both phospholipid as well as sterol biosynthesis. Therefore, the labeled lipids (in CE) represent not only phospholipids in membranes, but also cholesterol and triglycerides that form lipid droplets [36] . In this study, lipidomic analyses were carried out on both the 16K and CE subcellular fractions isolated from the 36 hr time point from DENV infected cells, UV-DENV exposed cells and the mock control. The primary lipids observed in the CE fraction were sphingolipids. Cholesterol and triglycerides were not successfully separated using our mass spectrometry analyses and very few phospholipids were observed to be statistically significant (p,0.05) in virus infected cells over the mock control (data not shown). Therefore, we focused our primary lipidomic analysis on lipids extracted from the 16K pellet at the 36 hr time point. Similar to the whole cell analysis, DENV infected cells displayed a unique expression profile compared to UV-DENV and mock infected cells ( Figure S2 ). Over 85% of the metabolites detected were significantly regulated in virus-infected cells compared to the controls. Analysis of the membrane fraction also highlighted several lipid species not detected in our whole cell analysis. An overall fold change (compared to mock) of the significantly (p,0.05) expressed lipid classes in the membrane fraction is shown in Figure 5 . For a complete list of differentially expressed lipids see Table S2 .