CHARACTERIZATION OF A FAMILY OF PISCIDIN HOST DEFENSE PEPTIDES IN THE STRIPED BASS Morone saxatilis AND WHITE BASS Morone chrysops

Scott A. Salger*, Katherine R. Cassady, Benjamin J. Reading
 
Department of Applied Ecology
North Carolina State University
Raleigh, NC  27695
sasalger@ncsu.edu

Host-defense peptides are components of the innate immune system. They are predominantly amphipathic, α-helical peptides with a broad-spectrum of action against viral, bacterial, fungal, and/or protozoan pathogens. Also known as antimicrobial peptides (AMPs), it has been recently shown that their activities extend beyond the traditional antimicrobial functions and may include anti-tumor, immunomodulatory, and antidiabetic effects. Piscidins are a family of host-defense peptides first discovered in the hybrid striped bass (HSB; white bass, Morone chrysops, x striped bass, M. saxatilis). We have identified six piscidins (P1, P3, P4, P5, P6, and P7) in the striped bass and white bass and have described their tissue distributions. We have also determined the progenitor species of origin of each piscidin expressed in the HSB and propose a revised nomenclature for the piscidin family based on a three class system defined by the lengths of the mature peptides. The Class I piscidins (22 amino acids in length; SB/WB P1, P3) show broad-spectrum activity against bacteria and ciliated protozoans, while the Class III piscidins (55 amino acids in length; SB/WB P6, SB P7) have activity mainly against protozoans (Tables 1 and 2). The Class II piscidins (44-46 amino acids in length; SB/WB P4, WB P5) have a level of activity against bacteria and protozoans intermediate to Classes I and III. Knowledge of piscidin function and activity may aid in the future development of disease-resistant lines of striped bass and white bass that could be used to produce superior HSB. Their expression and activity could relate to the enhanced disease-resistance observed in HSB compared either progenitor species.