STAT1-dependent tolerance of intestinal viral infection

Abstract

Recent evidence indicates that viral components of the microbiota can contribute to intestinal homeostasis and protection from local inflammatory or infectious insults. However, host-derived mechanisms that maintain tolerance to the virome remain largely unknown. Here, we use colonization with the model commensal murine norovirus (MNV CR6) to interrogate host-directed mechanisms of viral tolerance, and show that STAT1 is a central coordinator of tolerance following CR6 colonization. STAT1 restricts CR6 replication to the intestinal tract, prevents systemic viral-induced tissue damage and disease, and regulates antiviral CD4+ and CD8+ T cell responses. In contrast to systemic viral pathogens that drive T cell mediated immunopathology in STAT1-deficient mice, our data indicates that loss of CD4+ or CD8+ T cells and their associated effector functions has no effect on CR6-induced disease. However, therapeutic administration of an antiviral compound to limit viral replication prevented viral-induced tissue damage and death despite ongoing dysregulated antiviral T cell responses. Collectively, our data uncouple the requirement for STAT1-mediated regulation of antiviral T cell responses from innate immune-mediated restriction of viral replication that is necessary for intestinal viral tolerance.