Intracellular lipid droplets are exploited by Junín virus: a nucleoprotein-dependent process.

Lipid droplets (LDs) are organelles involved in lipid storage, maintenance of energy homeostasis, protein sequestration, signaling events and inter-organelle interactions. Recently, LDs have been shown to favor the replication of members from different viral families, such as the Flaviviridae and Coronaviridae. In this work, we found that LDs are essential organelles for members of the Arenaviridae family. A virus-driven reduction of LDs number was observed in cultures infected with Junín mammarenavirus (JUNV), caused in part by action of the viral nucleoprotein. To note, we identified a new pool of nucleoprotein and viral RNA that localize in the vicinity of LDs, suggesting that LDs play a role during the viral replication cycle. Regarding the mechanism behind LDs exhaustion, we found evidence that lipophagy is involved in LD degradation with the resulting fatty acids being substrates of fatty acid β-oxidation which fuels viral multiplication. This work highlights the importance of LDs during the replication cycle of JUNV, contributing to the knowledge of the metabolic changes these mammarenaviruses cause in their hosts.