A reasonable explanation is that this small increase in virus levels might have been derived from the activation of latently infected cells, which was reflected by our in vivo finding that malaria increased the activation level of CD4+ T cells (Figure 4A) and our in vitro finding that Plasmodium extract could induce activation of the main cellular reservoir, the memory CD4+ T cells (Figure 8B). The gene discussed is CD4; the disease is malaria.