Photorhabdus insect-related toxins A and B (Pir A and Pir B) are two different types of insecticidal toxins that were firstly found in Photorhabdus luminescens. Its homolog, from Vibrio parahaemolyticus, is found to cause acute hepatopancreatic necrosis disease (AHPND) in the shrimp, since it contains plasmid pVA1. When binded together, Pir A and B can exert its effect, because they form a stru…