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Diseases of Aquatic Organisms

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DAO 86:223-233 (2009)  -  DOI:

Application of a real-time PCR assay for the detection of Henneguya ictaluri in commercial channel catfish ponds

Matt J. Griffin1,2, Linda M. Pote3, Alvin C. Camus4, Michael J. Mauel2, Terrence E. Greenway1, David J. Wise1,*

1Thad Cochran National Warmwater Aquaculture Center, Mississippi Agricultural and Forestry Experiment Station,
2Department of Pathobiology and Population Medicine, College of Veterinary medicine, Mississippi State University, PO Box 197, Stoneville, Mississippi 38776, USA
3Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, PO Box 6100, Mississippi State, Mississippi 39762, USA
4Department of Veterinary Pathology, College of Veterinary Medicine, The University of Georgia, 501 DW Brooks Drive, Athens, Georgia 30602, USA
*Corresponding author. Email:

ABSTRACT: Proliferative gill disease (PGD) in channel catfish Ictalurus punctatus is caused by the myxozoan parasite Henneguya ictaluri. Prolonged exposure of channel catfish to the actinospore stage of the parasite results in extensive gill damage, leading to reduced production and significant mortality in commercial operations. A H. ictaluri-specific real-time (Q)PCR assay was used to determine parasite levels in commercial channel catfish ponds and evaluate the risk of losing fish newly stocked into the system. Previous research has shown the H. ictaluri actinospore to be infective for approximately 24 h; therefore, determining the parasite load (ratio of parasite DNA to host DNA) in sentinel fish exposed for 2 separate 24 h periods with a minimum of 1 wk between sampling indirectly represents the rate at which infective actinospores are being released by the oligochaete host and if that rate is changing over time. Alternatively, QPCR analysis of pond water samples eliminates the need for sentinel fish. Water samples collected on 2 separate days, with a minimum of 1 wk between sampling, not only determines the approximate concentrations of actinospores in the pond but if these concentrations are remaining stable. Increases in parasite load (r = 0.69, p = 0.054) correlated with percent mortality in sentinel fish, as did increases in mean actinospore concentrations (r = 0.63, p = 0.003). Both applications are more rapid than current protocols for evaluating the PGD status of a catfish pond and identified actinospore levels that correlate to both high and low risk of fish loss.

KEY WORDS: Channel catfish · Henneguya ictaluri · Myxozoa · Proliferative gill disease · Real-time PCR

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Cite this article as: Griffin MJ, Pote LM, Camus AC, Mauel MJ, Greenway TE, Wise DJ (2009) Application of a real-time PCR assay for the detection of Henneguya ictaluri in commercial channel catfish ponds. Dis Aquat Org 86:223-233.

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