Novel therapeutic approaches for hepatitis B virus covalently closed circular DNA

Figure 3 Clustered regularly interspaced short palindromic repeats/Cas9 system. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas system consists of a Cas9 nuclease and a single guide RNA (sgRNA), which leads Cas9 to the target site. A 20-nt complementary sequence to the target DNA is positioned at the 5′ end of the sgRNA, which is adjacent to the 5′ part of a proto spacer adjacent motif (PAM) matching the 5′-NGG sequence. The Cas9/sgRNA complex is guided to the target site via RNA-DNA complementary base pairing and induces site-specific double-strand breaks.