Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: Integrated Aquatic Animal Health Strategies

Location: Aquatic Animal Health Research

Title: Identification of unique DNA sequences present in highly virulent 2009 Alabama isolates of Aeromonas hydrophila

Authors
item Wei Pridgeon, Yuping
item Klesius, Phillip
item Mu, Xingjiang -
item Carter, Dominique -
item Fleming, Kristen -
item Xu, Dehai

Submitted to: Veterinary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 8, 2011
Publication Date: July 19, 2011
Repository URL: http://hdl.handle.net/10113/55614
Citation: Wei Pridgeon, Y., Klesius, P.H., Mu, X., Carter, D., Fleming, K., Xu, D. 2011. Identification of unique DNA sequences present in highly virulent 2009 Alabama isolates of Aeromonas hydrophila. Veterinary Microbiology. 152:117-125.

Interpretive Summary: In 2009, a disease outbreak caused by Aeromonas hydrophila occurred in 48 catfish farms in West Alabama, causing an estimated loss of more than 3 million pounds of food size channel catfish. Virulence studies have revealed that the 2009 isolates of Aeromonas hydrophila are at least 200-fold more virulent than a 1998 Alabama isolate AL98-C1B. However, up to now, no molecular markers have been identified to differentiate the highly virulent 2009 isolates from other isolates of A. hydrophila. To understand the genetic differences between the highly virulent 2009 isolates and the less virulent AL98-C1B at molecular level, PCR-select bacterial genome subtractive hybridization was used in this study. A total of 96 clones were selected from the subtractive genomic DNA library. Sequencing results revealed that the 96 clones represented 64 unique A. hydrophila sequences. Of the 64 sequences, three were confirmed to be present in the three virulent 2009 Alabama isolates but absent in the less virulent AL98-C1B. Using genomic DNAs from nine field isolates of A. hydrophila with different virulence as templates, two sequences were found to be only present in highly virulent A. hydrophila isolates, but absent in avirulent isolates. Our results suggest that these two unique DNA sequences might serve as unique molecular markers alone or in combination with other markers to identify highly virulent isolates of A. hydrophila.

Technical Abstract: In 2009, a disease outbreak caused by A. hydrophila occurred in 48 catfish farms in West Alabama, causing an estimated loss of more than 3 million pounds of food size channel catfish. Virulence studies have revealed that the 2009 isolates of A. hydrophila are at least 200-fold more virulent than a 1998 Alabama isolate AL98-C1B. However, up to now, no molecular markers have been identified to differentiate the highly virulent 2009 isolates from other isolates of A. hydrophila. To understand the genetic differences between the highly virulent 2009 isolates and the less virulent AL98-C1B at molecular level, PCR-select bacterial genome subtractive hybridization was used in this study. A total of 96 clones were selected from the subtractive genomic DNA library. Sequencing results revealed that the 96 clones represented 64 unique A. hydrophila sequences. Of the 64 sequences, three (hypothetical protein XAUC_13870, structural toxin protein RtxA, and putative methyltransferase) were confirmed to be present in the three virulent 2009 Alabama isolates but absent in the less virulent AL98-C1B. Using genomic DNAs from nine field isolates of A. hydrophila with different virulence as templates, two sequences (hypothetical protein XAUC_13870 and putative methyltransferase) were found to be only present in highly virulent A. hydrophila isolates, but absent in avirulent isolates. Our results suggest that these two unique DNA sequences might serve as unique molecular markers alone or in combination with other markers to identify highly virulent isolates of A. hydrophila.

Last Modified: 12/22/2014
Footer Content Back to Top of Page