FIG. 4.

Reproducibility of the sequencing assay for DR1-13/wild type ratio. Serum (50 μl) from a coinfected duck was divided into six portions, and the total DNA was extracted from each replicate sample and subjected to PCR and direct sequencing. The relevant portions of the G and C lanes are shown for each sample. The intensity of the DR1-13-specific C band at position 2547 (arrow) was measured for each sample and normalized to the combined intensities of the neighboring C bands at positions 2551 and 2552. The normalized value was compared with that obtained for a 1:1 mixture of DR1-13 and wild-type plasmid templates (std) to obtain the proportion of DR1-13, which is indicated as the percentage of DR1-13 below each pair of sample lanes.