Figure 5
Viral accumulation and egression.
(A) An electron micrograph of an ultrathin section of SGIV-infected cells (at 8 hpi) reveals the process of intracellular accumulation of viruses and various modes of viral egression including paracrystalline accumulation of mature viral particles (box 1), initiation of vacuolation (box 2), intracellular vacuolation (box 3), accumulation of virus in the form of a tubular vesicle in the vacuole (box 4); scale bar = 1 μm. (B) Paracrystalline array of dense viral particles accumulating in the VAS; scale bar = 200 nm. (C) Following vacuolation, vesicles containing mature viral particles bud into vacuoles; scale bar = 200 nm. (D) A series of slices from an area undergoing membrane tubulation reveals the unique spiral architecture of the membrane-deforming proteins that direct the vacuolar membrane tubulation induced by SGIV infection; scale bar = 100 nm. (E) Induction of viral-induced vesicle budding into a tubular structure begins with a recruitment of membrane-bending proteins that bind on the cytosolic side of the vacuolar membrane. The proteins form a unique spiral structure on the membrane, reshaping the vacuolar membrane into a membrane tubule which contains the virus inside the vacuole (arrows), scale bar = 100 nm. (F) Segmented contours imaging and the corresponding tomographic sections of viral-induced membrane buds and membrane tubules show the spatial distribution of the unique spiral structures, blue = vesicular membrane; green = viral particles; pink = spiral structures, scale bar = 100 nm.
