Here's what happens with infants. Infants are born with all of the antibodies that their mothers have, so while they may have the antibodies, they may not have the virus itself in them. If they are not exposed to the virus, either through the mother's blood during birth, or through her breast milk, once the kids develop their own antibodies, they will no longer have HIV antibodies, and standard tests for HIV will deem them HIV negative. If they receive the virus itself, they will become infected, and they will develop their own antibodies to the virus. So, if an HIV + mother feeds her child on formula or the milk of an HIV- woman, the child would probably test positive for HIV antibodies at birth, but test negative by age 2 (I forget the exact age, but it's between 1-2 years). There is nothing that can "cure" HIV in anyone who is infected with the virus itself. There are things that help prevent mother to child transmission, such as taking antivirals during pregnancy, not breastfeeding and the like. (NB: I say "cure" b/c curing a viral infection is something that modern medicine isn't terribly good at yet.)
