Such situations include recovery from infection that leads to the production of anti-HBs but is characterized by persistent low-grade viremia, production of ‘escape’ mutants that cannot be detected by HBsAg testing, “carriers” with antibody to the hepatitis B e antigen (anti-HBe) and anti-HBc, and carriers that are negative for anti-HBe and anti-HBc. The gene discussed is HBE1; the disease is infection.