Doctors from Johns Hopkins University in Baltimore believe that they may have found the missing link for a successful AIDS vaccine: an elite female suppressor. Reuters reports that researchers have come across a woman who has been living with HIV for 10 years and has never had to take meds because the amount of HIV in her blood has remained below the level of detection and has not damaged her immune system. Her husband, who is positive, has been on an aggressive therapy to control his HIV infection.

They both have the same strain of HIV, which is strong evidence that a component of the immune systems—not infection with a faulty virus—is responsible for the long-term suppression of HIV in elite suppressors. By studying her immune cells, doctors hope to understand how this woman has naturally been able to control her disease.

“That’s a good sign in terms of developing a therapeutic vaccine,” said Joel Blankson, MD, the study’s lead author. This type of vaccine would not prevent HIV, but would be used in treating people with HIV.