The antimicrobial peptides of the immune response of shrimp

The cultivation of penaeid shrimp is a worldwide economic activity which has the potential to contribute to increasing shrimp production. However, penaeid shrimps are susceptible to bacterial and viral diseases, and may thus cause significant losses to the aquaculture industry. In view of this, it is imperative to understand the immune response of shrimp against pathogens as this could help in devising efficient strategies to control, and eventually eradicate, shrimp diseases. At present, a considerable number of research studies on the identification and characterization of antimicrobial peptides/proteins (AMPs) in penaeid shrimps. Such research activities will contribute to finding solutions to shrimp diseases. AMPs are widespread in animals and plants, involved in their innate immunity, and considered as the front liners of host defense against pathogens. In penaeid shrimps, eight kinds of AMPs have been found. These are the penaeidins, whey acidic protein (WAP) domain containing proteins [crustins and single WAP domain containing peptides (SWD)], antilipopolysaccharide factors (ALFs), lysozymes, a C-type lectin, histones, anionic hemocyanins, and peritrophins. In this study, the structures, distributions, expression profiles, phylogenetic evolution, and functions of some AMPs are discussed, focusing on the WAP-domain containing peptides and ALF in penaeid shrimp.