Researchers have been searching for drugs that "shock" latent HIV to produce new viruses, which would kill those reservoir cells or target them for immune destruction. This new drug targets what's known as toll-like receptor 7 (TLR7) on immune cells. Researchers infected four monkeys with the simian AIDS virus, treated with the ARVs to fully suppress the infections, and then tried to mop up the reservoirs with the TLR7 drug. Although they did not cure the animals, they showed that the drug led their cells to spit out so many viruses that it became easy to find in their blood. They also found decreases in HIV DNA levels—a proxy for the reservoir—in tissues of three of the four animals.