Our previous findings have shown that HSV-CD80 infection exacerbates corneal scarring.22 We also have demonstrated that the suppression of CD80 in murine DCs, both in vivo and in vitro, is mediated by ICP22 binding to the CD80 promoter, resulting in downregulation of CD80 transcript and protein expression in APCs.22 From our published ICP22-CD80 functional studies, we were intrigued by the hypothesis to explore HSV-1–induced CS in vivo using ICP22 null virus infection. The gene discussed is CD80; the disease is Cowden syndrome 1.