Thus, HIV-1 latency and a latent reservoir consist mainly of CCR5-expressing cells and can occur due to (i) infection of activated memory T cells that persist in a memory T cell state, (ii) infection of resting memory T cells, (iii) infection of an activated thymocyte in the transition to naïve T cells, or (iv) infection of activated T cells that transition back to resting memory T cells (5, 14, 85, 88). The gene discussed is CCR5; the disease is infection.