Exciting new data presented today at the International Liver Congress 2013 include results from early in vitro and in vivo studies targeting covalently closed circular DNA (cccDNA), which may form the basis of a cure for chronic hepatitis B virus (HBV) infection.
HBV cccDNA is organized into mini-chromosomes within the nucleus of infected cells by histone and non-histone proteins. Despite the availability of efficient therapies against HBV, long-term persistence of cccDNA necessitates life-long treatments to suppress the virus. The following three experimental studies demonstrate effective HBV-cccDNA targeting/depletion using novel therapeutic approaches which offer the potential of a cure.
Liver regeneration induces strong reduction of viral replication and cccDNA levels, but not complete cccDNA eradication; without antiviral treatment, de novo HBV infection can be re-established.
Key findings of research in HBV-infected human hepatocytes using the uPA/SCID chimeric mouse system show that liver regeneration induces strong reduction of viral replication and cccDNA levels, with rapid formation of cccDNA-free hepatocytes. However, because complete cccDNA eradication is not achieved, in the absence of antiviral treatment, de novo HBV infection could be re-established in quiescent (non-dividing) human hepatocytes. This suggests that induction of hepatocyte turn-over together with antiviral drugs inducing viral suppression, such as nucleoside analogues and IFN, or blocking cell entry, may accelerate the clearance of the viral minichromosome.
Targeting epigenetic control of nuclear cccDNA minichromosome to suppress HBV transcription and replication may form basis for other therapeutic approaches to curing chronic HBV infection.
In the infected liver cell the rate of replication of HBV is regulated by the acetylation or methylation of histone proteins which surround the cccDNA minichromosome so called epigenetic regulatio
|Contact: Dimple Natali|
European Association for the Study of the Liver