Hepatitis B virus infection: pathogenesis, reactivation and management in hematopoietic stem cell transplant recipients.

Hepatitis B virus (HBV) is a partially double stranded DNA virus that can integrate into host cell chromosomes as covalently closed circular DNA forms. HBV reactivation following hematopoietic stem cell transplantation in recipients with evidence of past HBV exposure, as well as exacerbation of a current HBV infection in HBV carrier recipients, secondary to chemotherapy and post-transplant immunosuppression that affect both humoral and cell-mediated control of HBV infection, are well documented in the literature. Management options include HBV-DNA screening and antiviral prophylaxis. Nucleos(t)ide analogues have been used at the start of chemotherapy and pretransplantation, with the course continuing for 6 months. However, depending on the serum HBV-DNA level, the antiviral agent might be given until a therapeutic end point is reached.