Discovered: A Natural Protein in Breast Milk That Fights HIV
- 12 Ago 2014 alle 07:27:51
Scientists have identified a milk protein called Tenascin C that binds to HIV and prevents it from injecting its DNA into human cells
By Joseph Stromberg smithsonian.com

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.
The research, published today in Proceedings of the National Academy of Sciences, was inspired by previous work by other researchers showing that, both in tissue cultures and live mice, breast milk from HIV-negative mothers was naturally endowed with HIV-fighting properties. Scientists suggested that a few different proteins in the milk could potentially be responsible, but no one knew which one.
As part of the study, the researchers divided breast milk into smaller fractions made up of specific proteins via a number of filters—separating the proteins by size, electrical charge and other characteristics—and tested which of these fractions, when added to a tissue culture, prevented the cells from being infected by HIV. Eventually, using mass spectrometry, they found that one particular protein was present in all the HIV-resistant fractions but in none of the others: Tenascin C.
