Since LPLs result from the activity of PLA 2 -type enzymes, we investigated whether DENV infected cells displayed a higher activity of PLA 2 compared to uninfected cells. Utilizing a fluorescent PC substrate (BODIPY-PC) we used mass spectrometry to monitor the hydrolysis of PC to LPC by intracellular PLA 2 . Essentially, we monitored the production of BODIPY-LPC (resulting from PLA 2 mediated metabolism of PC) during a time course of DENV infection ( Figure S1 ) (method from [31] ). The assay indicated that following 24 hr of infection and longer, PLA 2 activity was elevated in DENV-infected cells compared to the controls, with the highest activity occurring at 48 and 72 hr postinfection. Therefore, the elevated levels of PLA 2 could be the source of the LPL detected in DENV-infected cells.