Primers mapped in the N-terminal third of the duck HBV pol gene. Ten microliters of the reaction mixtures was analyzed on 3.0% agarose/Tris-Cl–sodium acetate–EDTA (NuSieve, FMC) in the presence of 0.5 g of ethidium bromide per ml and photographed under UV illumination. The results were compared to those for uninfected controls.