For decades, public health officials have puzzled over a surprising fact about HIV: 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.
Now, a group of scientists and doctors from Duke University has figured out why these babies don’t get infected. Human breast milk naturally contains a protein called Tenascin C that neutralizes HIV and, in most cases, prevents it from being passed from mother to child. Eventually, they say, the protein could potentially be valuable as an HIV-fighting tool for both infants and adults that are either HIV-positive or at risk of contracting the infection.