Sources and signals regulating type I interferon production: lessons learned from cytomegalovirus

Type I interferons (IFN-αβ) are pleiotropic cytokines critical for antiviral host defense, and the timing and magnitude of their production involve a complex interplay between host and pathogen factors. Mouse cytomegalovirus (a β-herpesvirus) is a persistent virus that induces a biphasic IFN-αβ response during the first days of infection. The cell types and molecular mechanisms governing these 2 phases are unique, with splenic stromal cells being a major source of initial IFN-αβ, requiring communication with B cells expressing lymphotoxin, a tumor necrosis factor family cytokine. Here we review the factors that regulate this lymphotoxin-IFN-αβ "axis" during cytomegalovirus infection, highlight how stroma-derived IFN-αβ contributes in other models, and discuss how deregulation of this axis can lead to pathology in some settings.