This study provides further data to suggest that despite non-detectable plasma HIV-1 RNA levels, that replication competent proviral DNA exists in seminal fluid. Seven patients on HAART whose plasma and seminal RNA levels were below 50 copies/mL were examined for the presence of proviral DNA in PBMCs as well as in seminal fluid/cells using a CD8 depleted technique. From PBMCs, 3 of the seven patients had proviral DNA that was replication competent; conversely, 2 of the 7 had proviral DNA in seminal cells. Sequencing the proviral DNA from the V3 loop demonstrated the virus to be either dual or macrophage trophic -- this has important implications in that CCR5+ (macrophage) trophic strains are associated with sexual transmission. Therefore, despite the optimism presented in abstract 5, this abstract suggests that despite there being a non-detectable viral load in potential sanctuary sites, that replication competent virus is present and associated with strains that can be sexually transmitted using more sensitive techniques.