FIG. 5.

Formation of characteristic flavivirus CM/PC membrane structures upon expression of NS4A4B plus 2B3pro or NS2B-3-4A. Cryosections from transfected BHK cells were immunolabeled with antibodies to NS4A (A to C) or NS3 (D to F). Membrane structures visually analogous to those observed during flavivirus infection were induced during expression of NS4A-4B plus NS2B-3pro (C and D) or NS2B-3-4A (E and F). Similar membrane rearrangements were also observed during expression of NS4A-4B (A and B); however, these latter structures resembled loose chains of vesicles that may represent precursor structures to those observed in the other panels. Arrowheads indicate gold particles binding to the anti-NS3 or anti-NS4A antibodies, and the arrows indicate the individual vesicles within the induced membrane chains. Bars, 200 nm.