Our laboratory is interested in understanding the cellular and molecular mechanisms underlying the regulation of the immune system during viral infections, particularly infections with persistent viruses, which represent a serious health problem. To overcome the lack of small animal hosts for human persistent viruses, we use models of chronic viral infections in their natural murine hosts. In particular, by using chronic lymphocytic choriomeningitis virus (LCMV) infection in mice we have evaluated the dynamics of several cytokines (including interleukin-6 and transforming growth factor-b) and investigated their regulatory function on immune cells and their impact on the outcome of the infection at different times after viral challenge. By doing in-vivo studies at the whole organism level we are able to assess the impact of selected cytokine signaling in the context of the persistent infectious environment in which the immune cells are navigating. I will be presenting recent discoveries in this research area.