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Low level HIV replication in semen
persists in almost 10% of gay men taking antiretroviral therapy, investigators
from the United States report in the online edition of Clinical Infectious
Diseases. A low-level viral load in the blood and shedding of cytomegalovirus
(CMV) and Epstein Barr virus (EBV) in semen were associated with the detection
of HIV in the genital tract.
“Low levels of HIV in blood plasma
between 50 and 500 copies/ml were associated with seminal shedding, suggesting
that a complete suppression of HIV blood levels may minimize the risk of sexual
transmission,” the researchers comment.
Antiretroviral therapy suppresses
HIV replication in the blood and semen of most HIV-positive men, substantially
reducing the risk of sexual transmission.
However, genital shedding of HIV can
still occur in the presence of antiretroviral therapy. There have also been
rare case reports of HIV transmissions in the presence of therapy that is
suppressing viral load in blood plasma.
Untreated sexually transmitted
infections (STIs) can cause local inflammation, possibly increasing the risk of
transmission. Research involving people who have not taken HIV treatment (who
are antiretroviral naive) has also shown that some human herpes viruses
including CMV and EBV can cause immune activation or increase viral load in
semen.
Investigators from California
therefore designed a study exploring the relationship between STIs, seven
herpes viruses and shedding of HIV in semen.
Their study sample comprised 114 gay
and other men who have sex with men (MSM), all of whom were taking
antiretroviral therapy with a blood plasma viral load below 500 copies/ml.
Semen samples were collected and
tested for HIV replication and herpes viruses. The participants had a mean age
of 44 years. The median duration of antiretroviral therapy was 882 days and 88%
of participants had a blood plasma viral load below 50 copies/ml. The majority
of participants (87%) were highly adherent to their therapy, reporting taking
90% or more of their doses in the previous month.
An asymptomatic bacterial STI was
detected in 15% of individuals, including 4% with a urethral infection.
HIV was detected in the semen of 10%
of participants. The median genital tract viral load in these people was 126
copies/ml. A herpes virus was detected in the semen of 63% of participants. CMV
was detected in the genital tract of 49% of participants and EBV in the semen
of 31% of individuals.
People with a detectable blood
plasma viral load (between 50 and 500 copies/ml) were significantly more likely
to shed HIV in semen than individuals with undetectable virus in blood plasma
(36 vs 6%; RR = 6.0, 95% CI, 2.1-17.0, p < 0.001).
There was no relationship between
genital shedding of HIV and type of antiretroviral therapy, duration of
treatment or self-reported adherence.
High-level shedding of CMV (4 log10
or above) was also a predictor of genital shedding of HIV in semen. CMV at this
level was present in 64% of participants with detectable HIV in semen, compared
to 24% of participants with an undetectable HIV viral load in their genital
tract (RR = 4.5; 95% CI, 1.4-14.3, p = 0.01).
“High-level CMV replication plays a
role in HIV seminal shedding…in successfully treated HIV infected individuals,”
write the authors.
Detectable EBV in semen also had a
significant association with genital shedding of HIV (73 vs 26%; RR = 6.0, 95%
CI, 1.7-21.3, p < 0.01).
Surprisingly, the presence of a
urethral STI did not increase the risk of shedding HIV in semen. “This may be a
consequence of the relatively low prevalence of urethral STIs in this
asymptomatic cohort,” suggest the authors. “However, this also suggests that
CMV may be a more common precipitant of HIV shedding in semen than bacterial
STI during ART.”
They conclude, “the association
between isolated HIV shedding and high-level CMV replication and EBV
replication in the genital tract suggests that the presence of these viruses
could play a role in HIV transmission…these findings have important
implications for the development of strategies to reduce HIV transmission.”
The Friends of AIDS Foundation is
dedicated to enhancing the quality of life for HIV positive individuals and
empowering people to make healthy choices to prevent the spread of the HIV
virus. To learn more about The Friends of AIDS Foundation, please visit: http://www.friendsofaids.org.
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