The Vibrio parahaemolyticus subunit toxin PirB recognizes glycoproteins on the epithelium of the Penaeus vannamei hepatopancreas.

Vibrio parahaemolyticus toxin PirAB is the major virulence factor exotoxin that contributes to the disruption of the hepatopancreatic epithelium in acute hepatopancreatic necrosis disease in shrimp. The PirB subunit is a lectin that recognizes amino sugars; however, its potential role in recognition of the hepatopancreas has not been identified. In the present work, we identified the cellular receptor for PirB in the shrimp hepatopancreas. A ligand blot assay of hepatopancreas lysate showed that the PirB subunit recognizes two glycoprotein bands of 60 and 70 kDa (Gc60 and Gc70). The hepatopancreas lysate was fractionated by anion-exchange chromatography, and the three main fractions obtained contained the recognized Gc60 and Gc70 protein bands. LC-MS/MS indicated that beta-hexosaminidases subunit beta and mucin-like 5 AC corresponded to the 60 and 70 kDa bands, respectively, which seem to be expressed in the epithelial cells of the hepatopancreas. Endoglycosidase treatment of hepatopancreas lysate with the O-glycosidase from Enterococcus faecalis, inhibits the binding of PirB. Altogether, these results suggest the relevance of the interaction of PirB with the hepatopancreas in the pathogenesis of acute hepatopancreatic necrosis disease in shrimp.