Scientists have vaccinated pregnant cows, in order to get them to produce HIV-inhibiting antibodies in their milk.
Cows cannot contract HIV themselves. But they do produce antibodies in response to the invader. The milk that is first produced when a calf is born has a high level of antibodies (to protect the newborn from infection). This milk contained HIV antibodies when the cows were given HIV vaccines while pregnant.
If the scientists can formuilate a cream using this milk, it could be used to protect against the spread of HIV.