Current Microbiology, Vol.77, No.12, 3851-3860, 2020
Phylogenomic Analysis Supports Two Possible Origins for Latin American Strains ofVibrio parahaemolyticusAssociated with Acute Hepatopancreatic Necrosis Disease (AHPND)
Acute hepatopancreatic necrosis disease (AHPND) is a severe disease affecting recently stocked cultured shrimps. The disease is mainly caused byV. parahaemolyticusthat harbors the pVA1 plasmid; this plasmid contains thepirAandpirBgenes, which encode a delta-endotoxin. AHPND originated in China in 2009 and has since spread to several other Asian countries and recently to Latin America (2013). Many Asian strains have been sequenced, and their sequences are publicly accessible in scientific databases, but only four strains from Latin America have been reported. In this study, we analyzed nine pVA1-harboringV. parahaemolyticussequences from strains isolated in Mexico along with the 38 previously available pVA1-harboringV. parahaemolyticussequences and the reference strain RIMD 2210633. The studied sequences were clustered into three phylogenetic clades (Latin American, Malaysian, and Cosmopolitan) through pangenomic and phylogenomic analysis. The nucleotide sequence alignment of the pVA1 plasmids harbored by the Asian and Latin American strains confirmed that the main structural difference in the plasmid between the Asian and Latin American strains is the absence of the Tn3 transposon in the Asian strains; in addition, some deletions in thepirABregion were found in two of the Latin American strains. Our study represents the most robust and inclusive phylogenomic analysis of pVA1-harboringV. parahaemolyticusconducted to date and provides insight into the epidemiology of AHPND. In addition, this study highlights that disease diagnosis through the detection of thepirAandpirBgenes is an inadequate approach due to the instability of these genes.