Fig. 1.

Bisulfite sequencing of hepatitis B virus covalently closed circular DNA. HBV cccDNA are linearized with BstEII digestion prior to the bisulfite conversion, which converts the unmethylated cytosine (blue) to uracil (the uracil amplified as thymine in PCR), while 5-methyl-cytosine remains as cytosine (red). The converted DNA are PCR amplified and cloned into T-vectors. Methylated cytosine is discriminated from the unmethylated cytosine through the selective reaction