A vaccine for the monkey equivalent of HIV appears to eradicate the virus, a study suggests.
Research published in the journal Nature has shown that vaccinated monkeys can clear Simian Immunodeficiency Virus (SIV) infection from their bodies.
It was effective in nine of the 16 monkeys that were inoculated.
The US scientists say they now want to use a similar approach to test a vaccine for HIV in humans.
Prof Louis Picker, from the Vaccine and Gene Therapy Institute at Oregon Health and Science University, said: "It's always tough to claim eradication - there could always be a cell which we didn't analyse that has the virus in it. But for the most part, with very stringent criteria... there was no virus left in the body of these monkeys."
The research team looked at an aggressive form of virus called SIVmac239, which is up to 100 times more deadly than HIV.
Infected monkeys usually die within two years, but in some inoculated primates the virus did not take hold.
The vaccine is based on another virus called cytomegalovirus (CMV), which belongs to the herpes family.
It used the infectious power of CMV to sweep throughout the body. But instead of causing disease, it has been modified to spur the immune system into action to fight off the SIV molecules.
"It maintains an armed force, that patrols all the tissues of the body, all the time, indefinitely," explained Prof Picker.