Application

A therapeutic technique to eliminate infection of patients suffering from chronic Hepatitis B Virus infection.

Key Benefits

• May provide a cure for chronic HBV infection rather than just simple management.
• High efficiency of infection targeting may produce minimal side effects.
• May be used in combination with other HBV inhibitors.

Market Summary

Hepatitis B virus (HBV) is a major human pathogen that can cause serious liver complications. Current treatments for chronic HBV infections work to prevent viral spread by blocking viral replication or stimulating the host immune system. However, these treatments cannot cure the infection because they do not target the stable viral covalently closed circular (ccc) DNA molecules in infected hepatocytes. New gene modification techniques, such as CRISPR/Cas9, have been developed to target cccDNA for HBV therapy. However, previous attempts to knockout or disrupt the HBV pool of cccDNA present in chronically infected hepatocytes have found limited success due to the inefficiency of the knockout systems employed. The success of CRISPR-mediated targeting of cccDNA for HBV therapy may depend upon the ultimate efficiency of disrupting specific HBV sequences. The actual sequences to be targeted are determined in the experiment by using additional HBV-specific single guide sgRNAs (strand).

Technical Summary

Emory researchers have developed a novel CRISPR/Cas9-based system that can effectively repress viral DNA production, including cccDNA accumulation, in chronically HBV-infected cells and inhibit de novo HBV infection. The system uses lentiviral vectors encoding Spy Cas9/sgRNA combinations targeted to the HBV reverse transcriptase (RT), surface antigen (Ag), or core protein genes. In vitro studies have demonstrated that all three sgRNAs reduced HBV DNA levels inside cells by ~10 to ~125-fold and in the supernatant media by ~100 to ~800-fold, as measured by real-time PCR. The RT sgRNA suppressed HBV DNA replication to the same extent as Tet addition, which essentially entirely blocks virus replication. Overall, Cas9/sgRNA combinations specific for HBV reduced total viral DNA levels by up to ~1000-fold and HBV cccDNA levels by up to ~10-fold and mutationally inactivated the majority of the residual viral DNA. Furthermore, the researchers also showed that the CRISPR/Cas9-based system could be combined with known pharmacological inhibitors of the HBV RT enzyme to achieve additive inhibition of HBV DNA accumulation, strongly suggesting that the system has the potential to be used as an effective treatment for chronic HBV infection.

Developmental Stage

Preclinical stage of development.