Test Details: Hepatitis B is a vaccine-preventable liver infection caused by the hepatitis B virus (HBV). Hepatitis B is spread when blood, semen, or other body fluids from a person infected with the virus enters the body of someone who is not infected. This test can detect the emergence of mutations associated with resistance to antiviral drugs. The presence of resistance-associated mutations in patients with virologic breakthrough or rebound may guide changes in treatment regimen.