The persistence of HBV in recovered patients even many years after the onset of the infection has been proved by: (a) the persistence of HBV-DNA and HBV-specific CD8+ cytotoxic T lymphocytes (CTLs), (b) the reactivation of HBV with HBsAg seroreversion while receiving immunosuppressive therapy, and (c) infections by liver transplantation to HBV non-immune recipients from donors with inactive infection [73,74,75,76,77,78]. This evidence concerns the gene CD8A and infection.