Horizontal Plasmid Transfer Promotes the Dissemination of Asian Acute Hepatopancreatic Necrosis Disease and Provides a Novel Mechanism for Genetic Exchange and Environmental Adaptation
Songzhe Fu, Dawei Wei, Qian Yang, Guosi Xie, Bo Pang, Yongjie Wang, Ruiting Lan, Qingyao Wang, Xuan Dong, Xiaojun Zhang, Jie Huang, Jie Feng, Ying Liu
Abstract
Global outbreaks of shrimp acute hepatopancreatic necrosis disease (AHPND) caused by V. parahaemolyticus represent an urgent issue for the shrimp industry. This study revealed that the transmission mode of AHPND consists of two steps, the transregional dissemination of V. parahaemolyticus and the horizontal transfer of an AHPND-associated plasmid. Surprisingly, the introduction of the AHPND-associated plasmid also offers a novel mechanism of genetic exchange mediated by insertion sequences, and it improved the fitness of V. parahaemolyticus in a harsh environment. The results presented herein suggest that current shrimp farming practices promote genetic mixture between endemic and oceanic V. parahaemolyticus populations, which introduced the plasmid and accelerated bacterial adaptation by the acquisition of ecologically important functions. This entails a risk of the emergence of new virulent populations both for shrimp and humans. This study improves our understanding of the global dissemination of the AHPND-associated plasmid and highlights the urgent need to improve biosecurity for shrimp farming.