iii. Peptidoglycan recognition proteins. Peptidoglycan recognition proteins (PGRPs) specifically bind peptidoglycans, which is a major component of the bacterial cell wall. This family of proteins influences host-pathogen interactions through their pro-and anti-inflammatory properties that are independent of their hydrolytic and antibacterial activities. In bivalves, they were first identified in the scallops C. farreri and A. irradians [49, 50] and the Pacific oyster C. gigas, and from the latter four different types of PGRPs were identified [51] .