HBV sequencing and genotyping
The PCR products amplified by the S region primers
were sequenced; the readable sequences were more than
180 bps and contained the sequences of the “a” determinant
of HBsAg. Sequencing data demonstrated that
none of them was identical to the known sequences
detected in our laboratory and there were at least 2 bps
differences among the different plasmas, excluding the
false positive caused by cross-contamination. A single
base deletion was detected in the S region from a
donor, and no mutation in the “a” determinant was
observed in four other donors after comparing with the
known wild sequences in the GenBank. Phylogenetic
analysis of the partial S-gene sequences from the five
samples and corresponding sequences recovered from
GenBank demonstrated that the viruses in the five samples
all belonged to genotype B (Figure 2).