Breasts. They have always been wonderful things, but they are even more wonderful today, as scientists have identified the naturally occurring protein in breast milk that can block the HIV virus from infecting immune system cells. Its name is Tenascin-C and, according to the paper published in Proceedings of the National Academy of Sciences, it can potentially derive in a treatment for individuals with HIV or in risk populations.
We knew that, somehow, babies with HIV-positive mothers have a very low risk of becoming infected. According to Smithsonian Magazine, "only about 10-20 percent of infants who are breastfed by infected mothers catch the virus. Tests show, though, that HIV is indeed present in breast milk, so these children are exposed to the virus multiple times daily for the first several months (or even years) of their lives."
Scientists suspected that one or more proteins were the key to this baffling phenomenon but the mystery hasn't been revealed until now. The paper describes that this "innate HIV-neutralizing protein in breast milk [...] captures and neutralizes HIV-1 virions via binding to the chemokine coreceptor binding site on the HIV-1 Envelope."
Now scientists have to identify which part of Tenascin-C is responsible for this behavior. They also need to conduct experiments in live animals. In the future—according to the Smithsonian—"possible uses include giving it in a concentrated form to infants who can't breastfeed or even administering it to those who do to increase their level or resistance. It's even conceivable that it could someday be adapted to reduce the risk of HIV transmission in adults as well."