Immunoglobulin-like cell adhesion molecules, nectins - Characterization, functional prediction and expression profiling from seven-band grouper, Hyporthodus septemfasciatus

Abstract

Here, we report the characterization of four calcium-independent cell adhesion molecules, viz- nectin-1, 2, 3 and 4 from seven-band grouper Hyporthodus septemfasciatus a high valued marine finfish susceptible for nervous necrosis virus (NNV) infection. Structural analysis of the nectin molecules revealed an N-terminal V domain, two constant C2 domains, a transmembrane domain, and a cytoplasmic tail. All the nectin molecules except nectin-4 shared a C-terminal interaction motif (E/AxYV). Phylogenetic analysis revealed a close relationship between seven-band grouper nectins and zebrafish nectins. Also, nectins ubiquitously expressed in all the tissues of healthy fish with higher transcript abundance in the brain, gill and anterior kidney. Significant up-regulation of nectin-4 expression was observed in the brain of NNV challenged fish followed by the gill and kidney. Further, docking simulations of nectins with NNV capsid proteins revealed a strong interaction with nectin-1 and nectin-4. Our findings suggest that nectins might have a possible role to play in NNV neuropathogenesis. The present observations provide potential clues for further elucidating the involvement of nectins in NNV pathogenesis and could help in the development of new antiviral therapeutics inhibiting the NNV entry to the cell.