these results were confirmed by directly analyzing low molecular weight DNA from transduced cell by Southern blot. cccDNA and its deproteinated relaxed circular form precursor were greatly depleted in Cas9/sgRNA transduced cells. In contrast, when total HBV DNA was analyzed, no substantial reduction in the levels of integrated HBV DNA was detected. we then performed the Surveyor assay on HBV, to direcly determine whether the viral DNA was cleaved and repaired via error-prone NHEJ similar to genomic targets of CRISPR/Cas9. Interestingly,analysis of total HBV DNA forms for indel formation,an indirect measure ofCas9-mediated cleavage,