Identification and molecular characterization of two immune-responsive chitinase-like proteins from Anopheles gambiae

Two haemolymph proteins that are processed rapidly and specifically in response to exposure to bacteria have been identified from Anopheles gambiae. Both proteins, Anopheles gambiae bacteria-responsive 1 (AgBR1) and AgBR2, are similar to chitinases but belong to a family of proteins that have lost chitinolytic activity. AgBR1 and AgBR2 are converted to smaller forms in vivo or in vitro on exposure to bacteria, and AgBR2 also can be processed on exposure to peptidoglycan alone. AgBR1 and AgBR2 do not bind to bacteria or chitin beads. The AgBR1 and AgBR2 genes are expressed in all developmental stages. In adults, AgBR1 expression is restricted to the fat body, whereas AgBR2 is expressed in many tissues.