FIG. 6.

Reduction of DGD protein levels and impairment of DHBV infection by a 1:20 dilution of DGD antibodies added soon after virus binding. (A) Effect of rabbit serum added immediately following DHBV attachment. Left panels, PDH were incubated with a low dose of viremic duck serum for 6 h, washed, and immediately incubated with DGD preimmune or immune serum at various dilutions for 48 h. Cells were harvested 1 week postinfection. Viral DNA replication (upper left panel) and DGD levels (lower left panel) were measured. Right panel, cells infected with DHBV for 6 h were incubated with a 1:20 dilution of preimmune or immune serum for 24 h and harvested immediately. The protein-free DNA forms were analyzed. (B) Temporal effect of DGD antibodies. PDH were infected with viremic duck serum for 6 h and harvested 1 week postinfection. Rabbit serum (preimmune, immune, or nonrelevant) at a 1:20 dilution was present during the 6-h DHBV infection (left panels) or at different points following infection for 48 h (right panels). DGD protein levels at the time of harvest are shown in the lower panels, while markers for productive infection, such as viral DNA and core and envelope proteins, are shown in the upper panels. (C) Effect of DGD antibodies on DGD protein levels in DHBV-free cells. PDH were incubated with various dilutions of DGD immune serum for 1 or 2 days and harvested immediately for analysis of DGD levels. The GAPDH levels were measured to control for protein loading.