Seeking the AIDS virus in semen.Seeking the AIDS virus in semen AIDS is a sexually transmitted disease sexually transmitted disease (STD) or venereal disease, term for infections acquired mainly through sexual contact. Five diseases were traditionally known as venereal diseases: gonorrhea, syphilis, and the less common granuloma inguinale, , yet scientists know very little about the prevalence of the AIDS-causing virus (HIV HIV (Human Immunodeficiency Virus), either of two closely related retroviruses that invade T-helper lymphocytes and are responsible for AIDS. There are two types of HIV: HIV-1 and HIV-2. HIV-1 is responsible for the vast majority of AIDS in the United States. ) 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 Harvard Medical School (HMS) is one of the graduate schools of Harvard University. It is a prestigious American medical school located in the Longwood Medical Area of the Mission Hill neighborhood of Boston, Massachusetts. obtained blood and semen samples from 25 homosexual men whose blood had previously shown antibodies to HIV. Using a technique called polymerase chain reaction polymerase chain reaction (pŏl`ĭmərās') (PCR), laboratory process in which a particular DNA segment from a mixture of DNA chains is rapidly replicated, producing a large, readily analyzed sample of a piece of DNA; the process is (PRC), they searched the semen samples for a specific piece of HIV genetic material. They found the telltale DNA DNA: see nucleic acid. DNA or deoxyribonucleic acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. in only one of the 25 semen specimens. Van Voorhis, now at the University of Iowa Not to be confused with Iowa State University. The first faculty offered instruction at the University in March 1855 to students in the Old Mechanics Building, situated where Seashore Hall is now. In September 1855, the student body numbered 124, of which, 41 were women. in Iowa City, says PCR PCR polymerase chain reaction. PCR abbr. polymerase chain reaction Polymerase chain reaction (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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