Vibrio mimicus digests intestinal peritrophin-44 and disrupts hemolymph bacterial balance in crustaceans

Abstract

Bacterial colonization occurs in both the intestinal tract and hemolymph of crustaceans. The maintenance of hemolymph microbial homeostasis is essential for sustaining host health. In this study, we observed that oral administration of Vibrio mimicus significantly increased the bacterial load in crayfish (Procambarus clarkii) hemolymph. V. mimicus secretes the zinc-dependent metalloproteinase StcE, a secreted protease of C1 esterase inhibitor. VmStcE degrades peritrophin-44 (PP44) to break down the intestinal barrier of crustaceans. V. mimicus infection increases the expression of the host gene encoding inter-α-trypsin inhibitor heavy chain 4 (ITIH4). ITIH4 can inhibit the enzymatic activity of VmStcE. This study elucidates the molecular mechanisms of V. mimicus induced damage to crustaceans and provides a new perspective on the imbalance of hemolymph bacteria in crustaceans.