Study on the therapeutic effects of an extract of herb medicines, YiGanQingDuKeLi, in combination with adefovir dipivoxil on the rebound of duck hepatitis B virus multiplication
Objective 
To investigate the in vivo therapeutic effects of an extract of herb medicines, YiGanQingDuKeLi, in combination with adefovir dipivoxil (ADV) on the rebound of duck hepatitis B virus (DHBV) multiplication after withdrawal of ADV treatment. 
 
 
Methods 
Peking ducks were infected with DHBV positive serum samples for 7 days and then screened by SYBR Green real-time PCR. The ducks positive for DHBV were randomly divided into five groups including the model control group, the ADV treatment group, the herb treatment group, the high-dose combination therapy group and the low-dose combination therapy group. The ducks in the ADV treatment and the herb treatment groups were respectively treated with distilled water and YiGanQingDuKeLi (1.2 g/ml) for 14 days after the treatment of ADV (0.25 mg/ml) for 21 days. The ducks in the high-dose group were treated with YiGanQingDuKeLi (1.2 g/ml) for 14 days after the combined treatment with high-dose YiGanQingDuKeLi (1.2 g/ml) and ADV (0.25 mg/ml) for 21 days. The ducks in the low-dose group were treated with YiGanQingDuKeLi (0.6 g/ml) for 14 days after the combined treatment with YiGanQingDuKeLi (0.6 g/ml) and ADV (0.125 mg/ml) for 21 days. Blood samples were collected from each duck via leg vein after 0, 7, 14 and 21 days of drug administration and after 7 and 14 days of drug withdrawal. The levels of DHBV-DNA, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in blood serum samples were detected. 
 
 
Results 
Compared with the model group, the levels of DHBV-DNA, ALT and AST in ducks from the herb treatment group and combined treatment groups were decreased before the discontinuation of ADV treatment (P<0.05 or P<0.01). Moreover, the titers of DHBV-DNA in ducks treated with high doses of drugs were much lower than those from ADV treatment group. The levels of DHBV-DNA, ALT and AST in ducks treated with herb medicine and high doses of drugs remained at relatively low levels after the cessation of ADV treatment, but rebounded significantly in ducks with ADV treatment. The levels of DHBV-DNA and ALT rebounded slightly in ducks treated with low doses of drugs as compared with those of ADV treatment group (P<0.01 or P<0.05). 
 
 
Conclusion 
The treatment of YiGanQingDuKeLi in combination with ADV could inhibit not only the in vivo replication of DHBV, but also the rebound of DHBV multiplication after ADV withdrawal. 
 
 
Key words: 
Adefovir dipivoxil; Duck hepatitis B virus; Rebound