Figure 3

Working scheme of Pre-S Gene Chip analysis. The virus DNA is extracted from the patient's blood or liver tissue. The pre-S region is PCR-amplified using PCR-1R and 5'-dig-labeled 1F primers. The PCR products are visualized using agarose gel electrophoresis and ethidium bromide staining. In cases where no PCR products are seen---perhaps because of a low HBV DNA titer---nested PCR using PCR-2R and 5'-dig-labeled 1F primers is done. When only a single PCR product is seen, the DNA product is directly subjected to chip hybridization. However, when two or more different types of pre-S PCR products are seen in agarose gel, the products are first directed to TA cloning. Multiple plasmid clones are then analyzed using colony PCR with M13R and 5'-dig-labeled 13F primers. These PCR products are then analyzed using the Pre-S Gene Chip.