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Seeking the AIDS virus in semen.

Seeking the AIDS virus in semen

AIDS is a sexually transmitted disease, yet scientists know very little about the prevalence of the AIDS-causing virus (HIV) in semen. A new report hints that semen from some HIV-positive men may harbor tiny amounts of the virus or none at all.

Bradley J. Van Voorhis, Deborah J. Anderson and their colleagues at Harvard Medical School obtained blood and semen samples from 25 homosexual men whose blood had previously shown antibodies to HIV. Using a technique called polymerase chain reaction (PRC), they searched the semen samples for a specific piece of HIV genetic material. They found the telltale DNA in only one of the 25 semen specimens.

Van Voorhis, now at the University of Iowa in Iowa City, says PCR typically detects one HIV-infected cell per million and thus may miss HIV at lower concentrations. Indeed, when the team cultured semen samples for a month, they discovered HIV in four of 24 samples.

Extremely low levels of semen HIV might help explain why some people remain free of the infection despite unprotected sex with an infected partner, Van Voorhis says. Anderson notes, however, that other research by her team showed that some infected men intermittently shed HIV in semen -- a finding that underscores the gamble of unprotected sex. She and her co-workers are now attempting to unravel the mechanism underlying such shedding, in hopes that the work could lead to new methods of blocking sexual transmission of HIV in some cases.

In addition, future studies may improve the safety of donor seme used by infertile couples, Van Voorhis speculates. Semen consists of sperm and white cells, and the researchers suspect that semen HIV may reside in the white cells. If the researchers can confirm that suspicion, he says, clinicians might siphon out the white cells before sending sperm to donor banks. Fertility clinics currently screen semen donors with a blood test for HIV antibodies, which may fail to identify infection, he says.
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Author:Fackelmann, Kathy A.
Publication:Science News
Date:Nov 3, 1990
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