hcv hepatitis hbv infection active viral virus chronic load known hepatitis virus hbv hcv infection active known chronic positive patients virus hepatitis hcv hbv hiv immunodeficiency human infection known active antiviral infection chronic hepatitis requiring active therapy current hiv immunodeficiency virus hepatitis seropositive hcv hbv hiv immunodeficiency human viral known hbv hcv infection hiv active known htlv history deficiency disease hbv hcv virus hepatitis infection cleared known hiv chronic immunodeficiency