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ICAAC 2012: HIV May Be Shed in Semen Even If Blood Viral Load Is Undetectable


About 8% of HIV positive gay and bisexual men intermittently had detectable HIV viral load in their semen even when their blood viral load was fully suppressed, researchers reported at the 52nd Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2012) this month in San Francisco. This is more than twice the rate seen in a similar study of heterosexual men.

It is widely acknowledged that effective antiretroviral therapy (ART) that lowers the level of HIV RNA in the blood reduces the risk of HIV transmission. But transmission risk may depend more on viral levels in semen or vaginal fluid, and these may not match levels in the blood.

Jade Ghosn from Bicêtre Hospital in Paris and colleaguesevaluated the prevalence of HIV-1 shedding in the semen of HIV positive men who have sex with men (MSM) on successful ART with sustained undetectable blood viral load and no apparent sexually transmitted infections (STIs).

The analysis included 157 HIV positive men on combination antiretroviral treatment who had blood viral load < 50 copies/mL for at least 6 months (median 6.6 years). None showed symptoms of genital infections.

The median age was 44 years and the median time since HIV diagnosis was about 10 years. The median current CD4 T-cell level was high, at 637 cells/mm3, while the median nadir (lowest-ever) count was 247 cells/mm3; nearly 17% had a history of AIDS-defining events. Two-thirds had a stable partner, but two-thirds of those also had sex with others during the past 3 months, with a median of 10 casual partners.

The researchers analyzed HIV RNA levels in 2 paired blood and semen samples collected 1 month apart, looking at the relationship between semen viral load and levels of intracellular HIV DNA in peripheral blood mononuclear cells (PBMCs).


  • Semen viral load was detectable in 23 out of 304 samples, for a prevalence of 7.6%.
  • The median semen viral load was 145 copies/mL, range from 50 to 1475 copies/mL.
  • 5 people had detectable virus in their first semen sample, 14 did so in their second sample, and 2 did so in both samples.
  • 32 patients (21%) were found to have asymptomatic STIs including Ureaplasma urealyticum (18 people), syphilis (6 people), Gardnerella vaginalis (4 people), chlamydia (3 people), gonorrhea (2 people), and mycoplasma (1 person).
  • No significant associations were observed between detectable semen viral load and blood viral load, number of years on ART, treatment adherence, history of AIDS, current or nadir CD4 count, number of sex partners, or presence of STIs or hepatitis B coinfection.
  • Intracellular HIV DNA in PBMCs, however, was a significant predictor of detectable HIV in semen (odds ratio 3.1 for HIV DNA > 2.5 log copies/106 PBMCs; P = 0.015).

This first longitudinal study focusing on HIV positive gay men with supressed blood viral load and no symptoms of genital infection showed that, "HIV RNA can be detected in semen of HIV-1 infected MSM despite successful combination ART," the reseachers concluded. They noted that the 7.6% prevalence of detectable semen viral load in this study was signifcantly higher that the 3.1% rate obsrved in a previous study of heterosexual men.

"The [semen HIV] shedding was intermittent and not associated with the presence of a STI," they continued. "Whether such levels of [semen viral load] are infectious remains to be determined.



J Ghosn, A Delobelle, M Leruez-Ville, et al.Prevalence of HIV-1 Seminal Shedding in HIV-1 Infected Men who Have Sex with Men (MSM) and Association with the Size of Intracellular HIV-1 Reservoir (ANRS EP49). 52nd Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2012). San Francisco. September 9-12, 2012. Abstract H-1570f.