Pro- and anti-viral functions of lipid droplets in infection at a glance.

Lipid droplets (LDs) were long regarded as passive storage organelles for neutral lipids as this is the most efficient way to store energy. Recently, however, they have emerged as highly dynamic and heterogenous organelles that act as central hubs of lipid metabolic pathways. LDs provide lipids for energy production, supply precursor metabolites for many lipid classes, incorporate lipids under lipotoxic insults and are interconnected with other organelles through membrane contact sites. Viruses and all other obligate intracellular pathogens rely on metabolic networks in the host cell - including lipid metabolic pathways - for replication. Enveloped viruses need lipids for viral envelope formation, and positive-sense RNA viruses require lipids for formation of the membranous compartments in which they replicate. Additionally, like all intracellular pathogens, viruses require energy for their replicative cycle. Therefore, it is not surprising that several strategies have evolved by which viruses exploit various aspects of LD biology. Furthermore, recent evidence suggests that LDs might also have a function in inflammation. Both pro- and anti-viral roles of lipid droplets are discussed in this article.