Two hepcidins from spotted scat (Scatophagus argus) possess antibacterial and antiviral functions in vitro

• Two novel hepcidins (SA-hepcidin1 and SA-hepcidin2) were cloned from spotted scat.
• SA-hepcidin1 was widely expressed and SA-hepcidin2 only presented in liver.
• Synthetic SA-hepcidin1 had stronger antibacterial activity than SA-hepcidin2.
• Synthetic SA-hepcidin2 had antiviral activity, whereas SA-hepcidin1 did not.
• SA-hepcidins involved in resistance to various pathogens in the spotted scat.

Hepcidins are small cysteine-rich antimicrobial peptides that play an important role in host immunity against pathogenic organisms. In this study, two hepcidins, SA-hepcidin1 and SA-hepcidin2, were cloned from spotted scat (Scatophagus argus), and the tissue distributions of SA-hepcidins were determined. In addition, mature SA-hepcidin peptides were synthesized to allow evaluation of their antimicrobial and antiviral functions in vitro. SA-hepcidin1 belongs to the HAMP1 class and is widely expressed in all tested tissues from spotted scat, whereas SA-hepcidin2 belongs to the HAMP2 class and present only in the liver. The synthetic SA-hepcidins had similar levels of antibacterial activity against Gram-positive and Gram-negative bacteria; however, the antibacterial activity of SA-hepcidin1 was stronger than that of SA-hepcidin2. The antiviral activities of the synthetic SA-hepcidins were assessed against Siniperca chuatsi rhabdovirus (SCRV) and largemouth bass Micropterus salmoides reovirus (MsReV) in epithelioma papulosum cyprini (EPC) and grass carp fin (GCF) cells. SA-hepcidin2 had antiviral activity, but SA-hepcidin1 did not. The results of this study suggest that SA-hepcidins are important multifunctional proteins in the spotted scat immune system that are involved in resistance to various pathogens.