Recent studies have shown that the Porifera, with the examples of the demosponges Suberites domunculaand Geodia cydonium, comprise a series of pathways found also in the immune systemofDeuterostomia, suchas vertebrates, but are absent in Protostomia, with insects or nematodes as examples. One pathway is the (2¢)5¢)oligoadenylate syn-thetase [(2±5)A synthetase] system.