PirVP genes causing AHPND identified in a new Vibrio species (Vibrio punensis) within the commensal Orientalis clade

Abstract

Acute hepatopancreatic necrosis disease (AHPND) has extended rapidly, causing alarming shrimp mortalities. Initially, the only known causative agent was Vibrio parahaemolyticus carrying a plasmid coding for the mortal toxins Pir^VP. Recently, it has been found that the plasmid and hence the disease, could be transferred among members of the Harveyi clade. The current study performs a genomic characterization of an isolate capable of developing AHPND in shrimp. Mortality studies and molecular and histopathological analyses showed the infection capacity of the strain. Multilocus sequence analysis placed the bacteria as a member of the Orientalis clade, well known for containing commensal and even probiotic bacteria used in the shrimp industry. Further whole genome comparative analyses, including Vibrio species from the Orientalis clade, and phylogenomic metrics (TETRA, ANI and DDH) showed that the isolate belongs to a previously unidentified species, now named Vibrio punensis sp. nov. strain BA55. Our findings show that the gene transfer capacity of Vibrio species goes beyond the clade classification, demonstrating a new pathogenic capacity to a previously known commensal clade. The presence of these genes in a different Vibrio clade may contribute to the knowledge of the Vibrio pathogenesis and has major implications for the spread of emerging diseases.