Peptide P2 targeting Vibrio parahaemolyticus PirB toxins blocks the cytotoxic effects to shrimp Litopenaeus vannamei

Abstract

PirB is the main virulence factor of acute hepatopancreatic necrosis disease (AHPND) which induced the sloughing of hepatopancreatic cells and shrimp death. In addition, Litopenaeus vannamei aminopeptidase N (Lv-APN) is reported to be a functional receptor that mediates the pathogenicity by Vp_AHPND. This study aims to screen the PirB binding peptide to rescue the survival rate under Vp_AHPND infection. Here, the PirB toxin-binding peptides were selected using the random phage peptide library kit, and their biological function was verified by injecting them under Vp_AHPND challenge. The receptor candidates for PirB were genome-wide identified and selected based on gene expression profiles, and the biological function of Lv-APN1 was confirmed through RNAi. Docking analysis of Peptide-Lv-APN1 and PirB-Lv-APN1 was conducted using the MDockPeP server, with comparative analysis implied. As a result, a total of 11 PirB binding peptides were screened, among which P2 was found to effectively improve the shrimp survival rate under Vp_AHPND challenge. And knocked down of Lv-APN1, candidate receptor for PirB toxin, rescued mortality under Vp_AHPND challenge. Furthermore, docking analysis revealed that the interface of Lv-APN1 to rPirB was consistent with the P2 to rPirB, suggesting that P2 is likely to bind to PirB to block its binding to Lv-APN1 to reduce the mortality. In conclusion, both the injection of P2 and inference of Lv-APN1 can rescue the mortality of shrimp under Vp_AHPND challenge, and docking analysis revealed P2 is likely to bind to rPirB, blocking its binding to Lv-APN1 and reducing Vp_AHPND infection.