HIV RNA is detectable in semen in 5% patients with undetectable blood plasma viral attending fertility clinic

Simon Collins, HIV i-Base

In the context of quantifying levels of risk relating to natural conception in sero-different couples in relation to the recent Swiss Statement relating to undetectable viral load and risk of transmission [1], Anne-Genevieve Marcelin from Hopital Pitie-Salpetriere and colleagues reported rates of discordance between levels of HIV RNA in blood and semen in a cohort of 145 HIV-positive men enrolled in an assisted reproductive (sperm-washing) programme in Paris. [2]

The group, writing in a research letter to the August 2008 issue of AIDS, found that 5% of men in this group had detectable HIV RNA in semen.

264 paired blood and semen samples were collected between January 2002 and January 2008 with some patients providing up to six samples. Viral load was quantified using tests sensitive to 40 copies/mL and 200 copies/mL in blood and in seminal plasma respectively.

Thirty-two blood plasma samples were detectable (median 6,325 copies/mL (range: 222 to 28,300). Sixteen seminal plasma samples were detectable and the median level of HIV-1 RNA in semen was 1770 copies/mL (range: 255 to 25,100). Overall, 234 paired samples were concordant, with 225 samples with undetectable HIV-1 RNA both in blood and semen (85.3%) and nine with detectable HIV-1 RNA in blood and semen (3.4%). However, 23 blood samples had detectable HIV-1 RNA although the seminal viral load was undetectable and seven seminal samples had detectable HIV-1 RNA although the blood viral load was undetectable (range: 257 to 1,230 copies/mL).

These seven discordant paired samples corresponded to seven distinct patients who had undetectable viral load in blood for greater than six months and no current STIs. Interestingly, 6/7 had undetectable concordant results in blood and semen on at least one occasion during follow-up indicating variability over time. Antiretroviral drug levels in semen showed no relationship between choice of drug and viraemia: 3TC, FTC, tenofovir and indinavir showed higher penetration but were also included in many of the regimens that these seven patients were using.

The researchers concluded that their findings justify measuring HIV-1 RNA in semen when sero-different couples are planning a pregnancy. They also cautioned that a residual risk of transmission relating to these discordant results should be included in the information available to couples who would like to have unprotected sexual intercourse in the context of conceiving a baby.


It is interesting that level of discordance was intermittent in the seven patients with detectable viral load in semen, and that levels of viral load were generally low (maximum 1200 copies/mL).

As with the previous article, establishing whether a minimum threshold exists for transmission remains a crucial research question.

RNA testing of semen in the context of minimising risks in the context of conceiving a baby without sperm-washing is clearly an additional safety measure that should be used whenever possible – along with limiting conception attempts to the most fertile days of the woman’s cycle and possibly use of single-doses of tenofovir/FTC PrEP and PEP.


  1. Vernazza P, Hirschel B, Bernasconi E, Flepp M. HIV seropositive persons without sexually transmitted diseases under fully suppressive antiretroviral treatment do not sexually transmit HIV. Bulletin des medicins Suisses 2008; 89:165-169.
  2. Marcelin A-G et al. Detection of HIV-1 RNA in seminal plasma samples from treated patients with undetectable HIV-1 RNA in blood plasma. Research Letter. AIDS:Volume 22(13)20 August 2008p 1677-1679.

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