Yet another study has shown the extreme complexity of the viral reservoir, where HIV hides from antiretroviral (ARV) treatment, frustrating cure attempts. Researchers studied a single African-American man who was diagnosed with HIV in 2000 for 13 years after he started ARVs, until he died of cancer. They found that certain HIV-infected CD4 cells are able to survive over a considerable period of time and clone themselves. What’s more, the new cells they create contain virus with the potential to replicate and ultimately drive up the viral load if ARVs are stopped. This scientific insight may inform future research in the HIV cure arena, including efforts to eliminate the viral reservoir. At the same time, the study’s findings highlight the profound difficulty of ridding the body of all virus when only a single infected cell could reproduce a large population of such cells.