FIG 4.

CsCl density gradient analysis of hepatitis B viral particles. (A and B) CsCl density gradient analysis of viral particles in patient sera. One hundred-microliter volumes of serum mixture from patients 37, 38, 14, and 35 (25 μl each) and 100 μl serum from patient 17 were separated by CsCl density gradient centrifugation (2 ml of 1.18 g/cm³ CsCl solution in the upper layer and 2.9 ml of 1.33 g/cm³ CsCl solution in the lower layer). Viral DNA in each fraction was extracted and detected by Southern blotting. (C to G) CsCl density gradient analysis of viral particles treated with detergent or anti-HBcAg antibody (Ab). Concentrated HepAD38 cell culture supernatant (250 μl each) (via ultrafiltration) was either mixed with anti-HBcAg antibody (10 μl) followed by incubation without (C) or with NP-40 (final concentration, 1%) (D) for 1 h at room temperature and 4 h on ice or treated with only NP-40 (G) and then fractionated by CsCl density gradient ultracentrifugation. Sera from CHB patient 46 either left untreated (E) or treated with NP-40 (final concentration, 1%) (F) were fractionated by CsCl density gradient ultracentrifugation. Viral DNA in each fraction was extracted and subjected to Southern blot analyses.