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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
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.
Julia W. Pridgeon
Phillip H. Klesius
lethal dose 50
Diseases of Aquatic Organisms 2011 v.94 no.3
Journal Articles, USDA Authors, Peer-Reviewed
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