Even so, the monkeys' immune systems were still able to control the HIV-1 infection. So, the researchers temporarily weakened their immune systems by depleting a type of white blood cell, known as a CD8 T-cell, that destroys virus-infected cells.

"When we depleted their CD8 cells, the infected monkeys developed disease closely mirroring that of human patients. For example they contracted AIDS-defining conditions including pneumocystis pneumonia, a textbook example of an opportunistic infection in AIDS," said Theodora Hatziioannou of Aaron Diamond. " Because it replicates what happens when HIV-1 compromises a human patient's immune system, our approach could potentially be used in the development of therapies and preventative measures for human patients."

HIV therapy and prevention research often relies on SIV since SIV can cause AIDS-like disease in nonhuman primates. However, SIV doesn't always behave the same way HIV-1 does.

"We still have one major hurdle to overcome: If we could get HIV-1 to cause AIDS without depleting the CD8 cells, we could replace models that make use of SIV for this research," Hatziioannou added.

The findings were published in the U.S. journal Science.