NgAgo-gDNA system efficiently suppresses hepatitis B virus replication through accelerating decay of pregenomic RNA

Covalently closed circular DNA (cccDNA) in the hepatocytes nucleus is responsible for persistent infection of Hepatitis B virus (HBV). Current antiviral therapy drugs nucleos(t)ide analogs or interferon fail to eradicate HBV cccDNA. Genome editing technique provides an effective approach for HBV treatment through targeting viral cccDNA. Natronobacterium gregoryi Argonaute (NgAgo)-guide DNA (gDNA) system with powerful genome editing prompts us to explore its application in inhibiting HBV replication. Preliminary function verification indicated that NgAgo/EGFP-gDNA obviously inhibited EGFP expression. To further explore the potential role of NgAgo in restricting HBV replication, 10 of gDNAs targeting the critical region of viral genome were designed, only S-142, P-263 and P-2166 gDNAs led to significant inhibition on HBsAg, HBeAg and pregenomic RNA (pgRNA) level in Huh7 and HepG2 cells transfected with pcDNA-HBV1.1 plasmid. Similar results were also found in HBV infected HLCZ01 cells and Huh7-NTCP cells. However, we failed to detect any DNA editing in S-142, P-263 and P-2166 targeting region through T7E1 assay and Sanger sequencing. Remarkably, we found that NgAgo/P-2166 significantly accelerated the decay of viral pgRNA. Taken together, our results firstly demonstrate the potential of NgAgo/gDNA in inhibiting HBV replication through accelerating pgRNA degradation, but not DNA editing.