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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03420

    Natural genetic transformation of Vibrio parahaemolyticus as potential mechanism of pVA1 plasmid acquisition causing AHPND

    Gerardo de Jesús Carrillo-Méndez, Lina Angélica Zermeño-Cervantes, Alberto Antony Venancio-Landeros, Sergio Francisco Martínez Díaz, César Salvador Cardona-Félix*

    *Corresponding author:

    ABSTRACT: Vibrio parahaemolyticus is the causative bacterium of acute hepatopancreatic necrosis disease (AHPND) in white shrimp Litopenaeus vannamei. This bacterium secretes protein toxins whose genes are encoded in an auto-transmissible plasmid called pVA1. The presence of this plasmid in V. parahaemolyticus is determinant for disease development. Its propagation is not only linked to bacterial colonisation capacity but also to horizontal gene transfer mechanisms. Nevertheless, the active uptake of plasmid, which is known as natural genetic transformation (NGT) had not been proposed as a possible acquisition mechanism of pVA1 plasmid among Vibrio species. Previous studies suggest that some Vibrio species have the ability to perform NGT in the presence of chitin. Therefore, the objective of this study was to evaluate the induction of NGT mediated by chitin in V. parahaemolyticus (ATCC-17802) through its ability to incorporate and express pVA1 plasmid. The results showed that a reference strain without plasmid can incorporate it under the appropriate transformation conditions, and cause mortality in white shrimp similar to that observed for pathogenic strains isolated from infectious outbreaks. Given the management and conditions of a shrimp farm with large amounts of chitinous exoskeletons it is feasible that NGT could be a possible acquisition mechanism of plasmid pVA1 among Vibrio species, turning a non-causative strain of V. parahaemolyticus into a causative strain. With this study, we seek to expand knowledge of the pathogenesis process mediated by NGT and a better understanding of the possible propagation mechanisms of emerging diseases in the aquaculture sector.