Study in mice indicates an unknown component of human breast milk may kill HIV

New research shows that something in breast milk kills HIV particles and infected cells; it also blocks HIV transmission in mice with a human immune system.

Even if the babies of HIV-positive mothers avoid infection during birth, about 15 percent contract HIV in early childhood. Since the virus can get into milk, breast-feeding has been one possible explanation.

To investigate further, Angela Wahl at the University of North Carolina at Chapel Hill and her colleagues created mice with human bone marrow, liver and thymus tissues that all became infected with HIV if the mice were given an oral dose of the virus. However, if the rodents were fed human breast milk contaminated with HIV, the virus wasn’t transmitted.

Previous research had hinted at breast milk’s antiviral properties, but it was unclear if they would prevent transmission. “We have shown that milk has an intrinsic innate ability to kill HIV,” J. Victor Garcia, who supervised the work, reported in the journal PLos Pathogens. The hunt is now on for the ingredient in breast milk that inhibits the virus.

Why do some breast-fed babies contract the virus, if breast milk doesn’t transmit HIV? It’s possible that suckling may expose babies to the virus in their mother’s blood.

—Linda Geddes, New Scientist