PGE2 has been observed to be anti-inflammatory not only in persisting viral infections [18] but also in other chronic diseases, such as various tumor types, in which COX2 and/or PGE2 expression by tumors or myeloid-derived suppressor cells have been correlated with suppression and deviation of antitumor T-cell responses, as well as with worse disease outcome [19, 42]. Here, PTGS2 is linked to viral infectious disease.