Antiviral Activity of a Turbot ( Scophthalmus maximus ) NK-Lysin Peptide by Inhibition of Low-pH Virus-Induced Membrane Fusion.

Global health is under attack by increasingly-frequent pandemics of viral origin. Antimicrobial peptides are a valuable tool to combat pathogenic microorganisms. Previous studies from our group have shown that the membrane-lytic region of turbot ( Scophthalmus maximus ) NK-lysine short peptide (Nkl _71⁻100 ) exerts an anti-protozoal activity, probably due to membrane rupture. In addition, NK-lysine protein is highly expressed in zebrafish in response to viral infections. In this work several biophysical methods, such as vesicle aggregation, leakage and fluorescence anisotropy, are employed to investigate the interaction of Nkl _71⁻100 with different glycerophospholipid vesicles. At acidic pH, Nkl _71⁻100 preferably interacts with phosphatidylserine (PS), disrupts PS membranes, and allows the content leakage from vesicles. Furthermore, Nkl _71⁻100 exerts strong antiviral activity against spring viremia of carp virus (SVCV) by inhibiting not only the binding of viral particles to host cells, but also the fusion of virus and cell membranes, which requires a low pH context. Such antiviral activity seems to be related to the important role that PS plays in these steps of the replication cycle of SVCV, a feature that is shared by other families of virus-comprising members with health and veterinary relevance. Consequently, Nkl _71⁻100 is shown as a promising broad-spectrum antiviral candidate.