Vasoactive Intestinal Peptide (VIP) Protects Nile Tilapia () againstInfection.

Abstract

Vasoactive intestinal peptide (VIP), a member of secretin/glucagon family, is involved in a variety of biological activities such as gut motility, immune responses, and carcinogenesis. In this study, the VIP precursor gene () and its receptor gene VIPR1 () were identified from Nile tilapia (), and the functions of On-VIP in the immunomodulation of Nile tilapia against bacterial infection were investigated and characterized.andcontain a 450 bp and a 1326 bp open reading frame encoding deduced protein of 149 and 441 amino acids, respectively. Simultaneously, the transcript of bothandwere highly expressed in the intestine and sharply induced by. Moreover, the positive signals of On-VIP and On-VIPR1 were detected in the longitudinal muscle layer and mucosal epithelium of intestine, respectively. Furthermore, both in vitro and in vivo experiments indicated several immune functions of On-VIP, including reduction of,,,, and, upregulation ofand, and suppression of inflammation. Additionally, in vivo experiments proved that On-VIP could protect Nile tilapia from bacterial infection and promote apoptosis and pyroptosis. These data lay a theoretical basis for further understanding of the mechanism of VIP guarding bony fish against bacterial infection.