Suppression of HBV replication and expression by CRISPR/Cas9 ribonucleoproteins.

HBV infection is a global public health problem. The current treatment using nucleotide analogues (NA) can suppress viral replication but cannot eliminate HBV infection due to the persistence of covalently closed circular DNA (cccDNA), which sustains HBV replication and integration into the host cell genome and is refractory to NA treatment. CRISPR/Cas9 has been used to disrupt integrated HBV DNA and minichromosomal cccDNA for HBV suppression, but its expression and delivery require viral or non-viral vectors, which pose safety concerns for human application. We have previously reported the use of synthetic guide RNA (gRNA)/Cas9 ribonucleoprotein (RNP) as a non-viral formulation for HBV gene editing and viral suppression. To formulate highly effective CRISPR/Cas9 modalities for HBV gene therapy, here we designed additional gRNA/Cas9 RNPs and compared their antiviral efficacy in HBV-transfected as well as -infected cells. We found that two selected gRNA/Cas9 RNPs (gRNA5/Cas9, gRNA9/Cas9, and particularly their combinations) elicited the most potent antiviral efficacy, as evidenced by the significant inhibition of HBV DNA, RNA, and protein productions. DNA sequencing of the treated cells revealed moderate to high rates of insertion and deletion (indel) or knock-out (KO) mutations at the HBV target genes. Gene alignment analysis showed a high level of conservation for both gRNA5 and gRNA9 target sequences across major HBV genotypes, indicating that these CRISPR-based gene editing therapeutics have the potential to target different HBV strains worldwide. Thus, these synthetic gRNA/Cas9 RNPs represent promising novel therapeutics that can be developed and utilized for HBV gene disruption and viral eradication.