hepatitis hiv known infection active history positive patients viral chronic cmv cytomegalovirus infection pcr retinitis active herpes viremia positive viral positive hiv known patients donor test hepatitis subject status excluded hepatitis chronic infection active acute history known carrier viral hiv opportunistic infections concurrent infection dosing cmv day previous viral active hepatitis known positive history patients tests active viral load infection viral hepatitis active chronic liver symptomatic disease cirrhosis nonviral known hepatitis indicating virus acute positive chronic test infection result known