Antibodies shield some infants from AIDS.

Antibodies shield some infants from AIDS

Scientists have known since 1981 that the AIDS virus can be transmitted from mother to fetus. But not all babies born to infected mothers develop the disease, and among those who do, symptoms may not appear until the infants reach 6 months to 1 year of age. The diagnostic uncertainty forces physicians to delay experimental AIDS treatments that might otherwise begin soon after birth.

Researchers now report that a new antibody test, given to pregnant women infected with the AIDS virus, may indicate whether the newborn will be infected. Such knowledge could allow earlier diagnosis and treatment for diseased infants.

Yair Devash of Ortho Diagnostics in Raritan, N.J., with colleagues at the Albert Einstein College of Medicine in New York City, examined blood serum from 15 infected mothers and their newborns. The four infants who did not develop AIDS had antibodies that bind tightly to a key surface protein of the virus at a region known as the principal neutralizing domain (PND). Three of the four mothers of these babies also had the tightly binding antibodies. In contrast, none of the infected infants or their mothers had these antibodies.

Although the antibodies appear to prevent transmission of the virus from mother to infant, they do not protect mothers from infection, the investigators note in the May PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES (Vol.87, No.9).

Underpinning the study was an assay developed by Devash to detect antibodies that bind most strongly to the PND region of an AIDS viral strain common in patients. Devash says other research groups had previously found a significant but smaller correlation between infant protection and maternal antibodies to the PND region of a laboratory strain of the virus. He suspects those studies yielded less dramatic results because they could not distinguish between tightly binding antibodies and weakly binding ones, which may not protect infants against infection. The new assay, he adds, could rapidly screen the effectiveness of potential AIDS vaccines by measuring the concentration of tightly binding antibodies they stimulate.