Horizontal gene transfer of thepirABgenes responsible for Acute Hepatopancreatic Necrosis Disease (AHPND) turns a non-Vibriostrain into an AHPND-positive pathogen

AbstractIn the past decade, shrimp farms, particularly those established in Asia, Mexico and South America suffered from the outbreak of an emergent penaeid shrimp disease known as Acute Hepatopancreatic Necrosis Disease (AHNPD). The PirA and PirB toxins produced by plasmid pVA1 inVibrio parahaemolyticuswere reported to cause the AHPND pathology. More recent research demonstrated thatV. parahaemolyticusis not the only species that can cause AHPND, as otherVibriospecies were also found to contain PirAB-containing plasmid. The present study assessed the Horizontal Gene Transfer (HGT) of AHPND that transforms genes (pirAandpirB) from AHPND positiveV. parahaemolyticusto non-AHPND and non-vibrio species identified asAlgoriphagussp. strain NBP. The HGT ofpirAandpirBgenes from the AHPND positiveV. parahaemolyticustoAlgoriphagussp. strain NBP was found to occur at different temperatures. The conjugation efficiency rate (n°) ofpirABfromV. parahaemolyticustoAlgoriphagussp. strain NBP at 30°C and 40°C showed 80-91% efficiency. Shrimp challenged with thepirAandpirBpositiveAlgoriphagussp. strain NBP also demonstrated typical pathognomonic AHPND lesions during the histopathologic examination.Author summaryAHPND is a significant threat to the shrimp industry leading to high losses. The results demonstrated that the conjugative transfer of thepirAandpirBpositiveV. parahaemolyticus(donor strain) to a non-Vibrioand non-pathogenic bacterium (recipient strain), successfully transformed the non-pathogenic bacterium into a disease-causing strain with a disease-causing capability similar to the donor strain. Initially,V. parahaemolyticusthat express the PirA and PirB toxins which encoded by a conjugative plasmid cause sloughing and degeneration of shrimp hepatopancreatic.