FIG. 8.

Persistence of low levels of viral CCC DNA in the liver despite a dramatic suppression of viral DNA synthesis during β-l-Fd4C therapy. At the end of the 4-week treatment with β-l-Fd4C, CCC DNA in the liver was analyzed after amplification by a specific PCR assay followed by hybridization of 25% of the PCR products with a full-length DHBV genome probe. CCC DNA was amplified with primers P1 and P3 (see Materials and Methods). The result of DHBV DNA detection by the same PCR assay in the liver of a control animal is also shown (duck number 341; 1% of PCR products were loaded on the gel). The results demonstrate viral persistence at the end of β-l-Fd4C treatment in ducks numbers 356, 358, 359, and 360.