Thymus: the source of latent HIV

Successful antiretroviral therapy results in a substantial reduction in viraemia but cannot eradicate HIV. The virus remains latent in a subset of cells where it avoids elimination by the immune system. In the April Nature Medicine, David Brooks and colleagues from the University of California at Los Angeles suggest that the thymus may be the source of latently infected cells, as latent HIV infection can occur during thymopoiesis.

They studied SCID-hu (Thy/Liv) mice, in which human thymic implants can reproduce thymopoiesis. These mice were infected with either CCR5- or CXCR4- tropic virus strains. Isolated mature CD4⁺ human thymocytes showed a substantial increase in virus production after stimulation, demonstrating the acquisition of latent virus during thymopoiesis. Brooks et al also report that the latently-infected cells are exported into the periphery, suggesting that the thymus may be a source of latent HIV in humans (Nat Medicine 2001, 7:459-464)....