HBV is a DNA virus. After it enters the cell, its DNA reaches the liver cell's nucleus and forms something called cccDNA¹; a circular, double-stranded DNA chain, sometimes called a mini-chromosome (or an episome). This cccDNA replicates itself and creates new viruses and is responsible for the persistence of infection. However, sometimes the replication is faulty and incomplete and creates DNA chains that are linear, not circular, called dslDNA².
Human enzymes in the nucleus can mistake this dslDNA for human DNA and misidentify it as a part of the host DNA that got broken, so they glue it back to the host genome, thus attaching the viral DNA to host DNA in hepatocytes.
This integrated DNA cannot make new viral copies, but can make some viral proteins and most importantly can attach to cancer-promoting regions³ in the genome, thus integrated HBV DNA is thought to be the reason why HBV-infected patients can develop hepatocellular carcinoma even in the absence of active infection or cirrhosis.
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¹ Covalently-Closed Circular DNA
² double-stranded linear DNA
³ Oncogenes
August 3, 2026 414
