Aeromonas veronii disease in the refined snakehead fish, Ophiocephalus argus (Cantor)

Abstract

Aeromonas veronii has been identified as a causative agent of fish and human disease outbreaks.
However, there is no definitive data on A. veronii infection in cultured snakehead fish Ophiocephalus
argus (Cantor). In this study, a virulent strain S-L was isolated from the farmed snakehead fish suffering
from epizootic ulcerative syndrome, and identified as an A. veronii strain using ARIS 2X system. Its
taxonomic position was further determined through nucleotide blast search in NCBI website and
phylogenetic analysis. The constructed phylogenetic tree using neighbor-joining method further showed
that the S-L isolate was the A. veronii strain (GenBank accession no. JQ301790), which was also
previously isolated from diseased freshwater fish. In addition, five genes encoding aerolysin,
haemolysin, serine protease and two cytotonic enterotoxins were all found present in the S-L isolate
which further confirmed its potential virulence. As far as we know, this is the first report of farmed
snakehead fish infected with A. veronii