Post-prostatic massage fluid/urine as an alternative to semen for studying male genitourinary HIV-1 shedding

Objectives: Genitourinary tract samples are required to investigate male HIV-1 infectivity. Because semen collection is often impractical, the acceptability, feasibility and validity of post-prostatic massage fluid/ urine (post-PMF/U) was evaluated for studying male genitourinary HIV-1 shedding. Methods: HIV-1-seropositive men were evaluated after 48 h of sexual abstinence. At each visit, a clinician performed prostatic massage, then post-PMF/U and blood were collected. Participants provided semen specimens 1 week later. An audio computer-assisted self-interview (ACASI) administered after each specimen collection evaluated acceptability, adherence to instructions and recent genitourinary symptoms. HIV-1 RNA was quantified using a real-time PCR assay. Detection and quantitation of HIV-1 RNA and stability over visits were compared for semen, post-PMF/U and blood. Results: Post-PMF/U was successfully obtained at 106 visits (64%) and semen at 136 visits (81%, p<0.001). In ACASI, discomfort was rated higher for post-PMF/U collection (p=0.003), but there was no significant difference in acceptability. Detection of HIV-1 RNA in post-PMF/U was associated with detection in semen (p=0.02). Semen and post-PMF/U HIV-1-RNA levels were correlated (r=0.657, p<0.001). Concordance of results at repeat visits was 78.9% for post-PMF/U (κ=0.519, p=0.02) and 89.5% for both blood and semen (κ=0.774, p=0.001). Conclusions: Although semen collections were more successful, both post-PMF/U and semen collections were acceptable to many participants. HIV-1 RNA detection and levels were closely associated in semen and post-PMF/U, and results were relatively stable across visits. To assess male HIV-1 infectivity, post-PMF/U may represent a valid alternative when semen cannot be obtained.