A hepcidin homolog from <i>Lateolabrax japonicus</i> inhibits the infection of Anguillid herpesvirus 1 by interacting with the viral envelope protein ORF51

Frequent outbreaks of eel "mucus sloughing and hemorrhagic septicemia disease" caused by Anguillid herpesvirus 1 (AngHV) are a major epidemic in both wild and farmed eels. This virus has garnered global attention due to heavy losses on eel farms and the lack of protective vaccines or effective drugs, highlighting the urgent need for potent antiviral agents. In this study, we revealed a hepcidin homolog LJ-hep2 from Japanese seabass (<i>Lateolabrax japonicus</i>) can bind to AngHV and impede viral entry into cells. LJ-hep2 could directly destroy the viral envelope and showed a higher anti-AngHV activity than AA-hep (a hepcidin homolog cloned from <i>Anguilla anguilla</i>). It was found that the destruction of viral structure by LJ-hep2 was related to the binding of the peptide to AngHV envelope protein ORF51, and the two amino acid residues at the N-terminus of the peptide (lysine and phenylalanine) might play a key role. Comparative antiviral experiments with mutated LJ-hep2 (LJ-hep2_A4A5) and multi-species hepcidin further confirmed this finding and demonstrated that these two amino acids were indispensable in the inhibition of AngHV infection by LJ-hep2. In an established eel immersion infection model, LJ-hep2 treatment reduced viral accumulation in tissues, inhibited horizontal transmission, alleviated skin lesions, and improved eel survival. Taken together, this study suggests that LJ-hep2 could inhibit AngHV infection <i>in vitro</i> and <i>in vivo</i>, and identify ORF51 as a potential target for the development of anti-AngHV drugs.