FIG. 5.
Subcellular localization of HCV proteins by immuno-EM. (A and B) Localization of HCV core (6-nm-diameter gold particles) and E2 (10-nm-diameter gold particles) in cell line 21-5. (A) The majority of the core protein is found on the surfaces of lipid vesicles (V), and only minor staining is detected at the ER. No 10-nm-diameter gold specific for E2 can be seen in the area around the vesicles. Note that no osmium postfixation was used, and therefore, the lipid vesicles appear empty, due to removal of the content by alcohol dehydration and embedding medium. (B) The 10-nm-diameter gold marker specific for E2 associated with elongated, cisterna-like structures in the cytoplasm presumably belonging to the ER and early compartments of the Golgi complex. Note the absence of 6-nm-diameter gold marker specific for core. (C) Specificity control of the immuno-gold labeling. Cell line 21-5 was labeled with primary antibodies directed against HIV and measles virus proteins, which share the isotypes of the antibodies used in panels A and B. Subsequently, the same gold-labeled secondary antibodies were used. Magnification, ×92,150.