In contrast to this, previously it has been shown that recombinant HSV-1 with a single mutation in amino acid 34 or 116 of ICP22 has reduced eye disease, compared with parental control virus.45,46 This discrepancy between our results and previous studies is possibly due to the fact that, while mutation in amino acid 34 or 116 of ICP22 affected virus replication and pathology, it did not eliminate its binding to CD80 promoter and thus still did suppress the immune response in the cornea of infected mice. Here, CD80 is linked to eye disorder.