IFNA1 and viral infectious disease: In addition to being involved in attrition, direct IFNα/β signaling leads to the specific upregulation of MHC Class I and Qa-1 on CD8+ T cells during in vitro stimulation and/or primary viral infection in vivo, and the failure to appropriately upregulate these and other inhibitory molecules allows the cells to be attacked by NK cells, limiting the expansion of the virus-specific CD8+ T cells [21].