DAO 94:249-253 (2011)  -  DOI: https://doi.org/10.3354/dao02332

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Molecular identification and virulence of three Aeromonas hydrophila isolates cultured from infected channel catfish during a disease outbreak in west Alabama (USA) in 2009

Julia W. Pridgeon*, Phillip H. Klesius

Aquatic Animal Health Research Unit, USDA-ARS, 990 Wire Road, Auburn, Alabama 36832, USA

ABSTRACT: Three isolates (AL09-71, AL09-72, and AL09-73) of Aeromonas hydrophila were cultured from infected channel catfish Ictalurus punctatus during a disease outbreak in west Alabama, USA, in August 2009. Sequence analysis of the 16S–23S rDNA intergenic spacer region (ISR), cpn60, gyrB, and rpoD genes of the 3 strains revealed that the 3 strains were closely related to each other, sharing 97 to 99% nucleotide sequence similarities. However, ISR sequences of the 3 isolates from 2009 shared only 64% nucleotide sequences with AL98-C1B, a 1998 isolate of A. hydrophila cultured from diseased fish in Alabama. Sequences of cpn60, gyrB, and rpoD from the 3 isolates from 2009 shared 91 to 95% homologies with AL98-C1B. Based on both LD50 and LD95 values of intraperitoneal injection assays, the virulences of the 3 isolates from 2009 were not significantly different from each other, but were at least 200-fold more virulent than AL98-C1B, indicating that the 3 west Alabama isolates of A. hydrophila from 2009 were highly virulent to channel catfish.


KEY WORDS: Aeromonas hydrophila · Molecular analysis · Virulence · Channel catfish


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Cite this article as: Pridgeon JW, Klesius PH (2011) Molecular identification and virulence of three Aeromonas hydrophila isolates cultured from infected channel catfish during a disease outbreak in west Alabama (USA) in 2009. Dis Aquat Org 94:249-253. https://doi.org/10.3354/dao02332

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