Molecular identification and in silico functional characterization of a histone H2A derived antimicrobial peptide from Tilapia lake virus (TiLV) infected Nile tilapia (Oreochromis niloticus)

Antimicrobial peptides (AMPs) constitute a unique class of low molecular weight peptides that are generated by the host innate immune system to elicit antimicrobial and immunostimulatory effects in all life forms. They are considered as novel therapeutic agents for combating multi drug resistance of infectious microorganisms. In the present investigation, a partial N terminal histone H2A derived AMP designated as Tilapia Hipposin (TiHip) was identified and characterized from tilapia lake virus infected tilapia Oreochromis niloticus . The virus infection in the fish was confirmed by molecular techniques, electron microscopy and in vitro cell culture studies. A 245 bp gene fragment that encoded 81 amino acid residues was identified from the gill tissue of the infected fish. This study is the first report of molecular identification of histone H2A derived AMP from virus infected nile tilapia. Phylogenetic analysis of TiHip indicated a close relationship with histone H2A sequences from other teleost fishes. Secondary structure prediction revealed the presence of α- helix and random coils and the helical wheel projection indicated the amphipathic nature of the peptide. The physicochemical properties, sequence similarity and structural characteristics of TiHip agreed with the characteristic attributes of AMPs, indicating its potential part in the innate immunity of fish. In silico functional analysis predicted antimicrobial, anti-inflammatory, anti-cancer, anti-biofilm and non-hemolytic activity which clearly suggested that TiHip could act as a potent bioactive peptide for therapeutic applications.