Hepatitis B virus structure, illustration. Hepatitis B virus (Hepadnavirid family). HBV causes sexually transmitted or blood-borne hepatitis. Cirrhosis occurs in 20% of cases 15 to 20 years after the onset of infection. Hepatitis B viruses (HBV) can integrate into host DNA as insertional mutagens causing the activation of a cellular proto-oncogene. Integration of viral DNA into the human genome is considered an early event in the carcinogenic process and can induce, through insertional mutagenesis, the alteration of gene expression and chromosomal instability.