The dynamics of DHBV-DNA in livers and sera of experimentally in-fected Beijing ducks was studied. After iatravenous inoculation of DHBV-positive Shanghai duck Serum into 3 days old Beijing ducklings,up to 72hrsafter infection, no evidence of DHBV-DNA in sera was found, 9hrs after infection, DHBV-DNA appeared in the liver extract of one of three infected ducklings. 48 and 54 hrs postinjection, DHBV-DNA were found in liver extracts of all 3 or 2 infected ducklings in each group. The average serum DHBV-DNA Ie...