The main reason scientists were unable to find a cure for the HIV virus is because of its ability to mutate and constantly change.

However, they have possibly found a way to prevent HIV infections. One of the bacteria that live in our bodies was genetically modified to secrete proteins that would block HIV from infecting the cells.

HIV transmission takes place on the surface of the gut and reproductive organs. When the bacteria were introduced in mice, they were found in the parts of lower gut and in the vagina although in smaller concentrations.
Even though these are still early stages of the study, scientists are hoping for a more practical and cheaper way to combat HIV. Bacteria are easier to manifacture, store and administer and less expensive. Besides from preventing HIV infections the bacteria could be used in treating people who already carry the virus.