PTGES and viral infectious disease: PGH2 can be further processed into PGE2 by prostaglandin E synthase (PTGES).18,19 The release of PGE2 by respiratory epithelial cells has been shown to be induced during viral infections,20–22 and PGE2 has also been shown to modulate immune cell function23 as well as to modify the IFN response during viral infections.24,25