Southern blot analysis of HBV cccDNA in infected human BMSCs. (A) HBV cccDNA was extracted from human BMSCs at 2, 4, 6, and 8 days after infection and subjected to Southern blot hybridization. DIG-labeled whole HBV DNA probe served as a positive control (lane M). Uninfected BMSCs served as a negative control (lane U). DNA sizes are indicated on the left (kb). (B) The cccDNA cleaved by E coRI was analyzed using Southern blot analysis.