Objective: To establish criteria for the quantitation of the human immunodeficiency virus (HIV) in seminal plasma, seminal cells and the whole semen of HIV-infected individuals. The reverse transcription polymerase chain reaction (RT-PCR), DNA-PCR and semen HIV culture assays were standardized by testing seminal plasma spiked separately with serial dilutions of cell-free and cell-associated HIV stocks of known titers. The standardized assays were then used to assess the quantity of virus in the freshly collected seminal cells and seminal plasma.
Results: Analysis of freshly collected peripheral blood mononuclear cells (PBMCs) and paired semen from HIV-seropositive men who had received antiviral drugs and/or immunemodulators indicated that HIV could be isolated from 42 of 55 (76%) samples of peripheral blood mononuclear cells (PBMCs) and 13 of 55 (24%) samples of ejaculates. Since no semen sample was culture positive in the absence of culturable HIV in PBMCs of the same individual, RT-PCR was 5-125 times more sensitive than cell cultures for the quantitation of HIV spiked in seminal plasma, freshly collected seminal fluid and whole semen. Further, HIV-RNA was detected in samples containing higher dilutions of virus from which HIV was not isolated by culture.
Conclusion: We conclude that cell-free HIV is present in excess of the culturable virus in all specimens tested and that the high sensitivity of HIV-RNA detection is useful for quantitation of the virus directly in seminal fluid, seminal cells and whole semen.