Cells expressing individual HCV proteins. (a) UNS3-4A-24 cells, expressing the proteins NS3 and NS4A, show smooth-surfaced vesicles of varying size. The vesicles are distributed in clusters in the cytoplasm. (b) Protein NS4B expressed by UNS4Bcon-4 cells induces a membranous web. Note the association of the web with remnants of the rER (arrowhead). (c) UCp7con-9.1 cells express the structural proteins core, E1, E2, and p7. Highly dilated rER vacuoles contain numerous invaginations of the rER, budding into the lumen of the large vacuole. Arrowheads, small buds; asterisks, large buds; N, nucleus. Bars, 0.5 μm.