Reactive oxygen species delay control of lymphocytic choriomeningitis virus

CD8+ T cells are of critical importance to prevent chronic viral infections because they not only promote virus elimination, but also induce virus mediated immunopathology. Elevated levels of reactive oxygen species (ROS) have been reported during virus infections. However, the role of ROS in T cell mediated immunopathology remains unclear. Here we used the murine lymphocytic choriomeningitis virus to explore the role of ROS during the processes of virus elimination and induction of immunopathology. We found that virus infection led to elevated levels of ROS producing granulocytes and macrophages in virus infected liver and spleen tissue that was triggered by the NADPH oxidase. Lack of the regulatory subunit p47phox of the NADPH oxidase diminished ROS production in these cells. While CD8+ T cells exhibited ROS production that was independent of NADPH oxidase expression, survival and T cell function was elevated in p47phox deficient (Ncf1-/-) mice. In the absence of p47phox, enhanced T cell immunity promoted virus elimination and blunted corresponding immunopathology. In conclusion, we find that NADPH-mediated production of ROS critically impairs the immune response, impacting elimination of virus and outcome of liver cell damage.