An array of inhibitory and activating receptors initially identified on NK cells are also expressed by conventional CD8+ alphabeta T cells. New evidence strongly implicates these 'NK cell receptors' in modulating NK cell and virus-specific CD8+ T cell responses against a variety of viral infections. Precise regulation of NK cell and T cell responses by these receptors optimizes antiviral immunity while preventing immunological bystander pathology and autoimmunity.