Figure 10.

Diagram comparing how lipid droplets are currently thought to form, versus our hypothesis for poxvirus membrane growth. Lipid droplets are thought to form within the membrane of the ER and then bud from it (top). Here, we propose that the crescent-shaped precursors of vaccinia IVs might acquire phospholipids from the ER membrane in a similar manner (bottom). In both cases, an unstable intermediate in the form of a “T-junction” might form transiently, as is thought to occur during all membrane fusion and budding events.