Submitted to: Journal of Aquatic Animal Health
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/26/2008
Publication Date: 3/1/2009
Citation: Elibol-Flemming, B., Wolters, W.R., Waldbieser, G.C., Boyle, C.R., Hanson, L.A. 2009. Expression Analysis of Selected Immune Relevant Genes in Channel Catfish During Edwardsiella ictaluri Infection. Journal of Aquatic Animal Health 21:23-35. Interpretive Summary: Catfish losses to pathogenic bacteria, especially the bacterium Edwardsiella ictaluri, significantly impact production. In order to measure innate defense mechanisms in response to E. ictaluri infection, and determine whether innate immunity in catfish and mammals is similar, an assay was developed to measure expression of several genes that are indicative of the innate immune response. Activity of the End binding protein 1 (EB1), heat shock protein 70 (hsp70), ß1-integrin, and natural resistance associated macrophage protein (Nramp), and transferrin genes increased after exposure to bacteria, while the serum amyloid P (SAP) gene activity decreased by 2 days after exposure. This supported the assumption that the products of the catfish genes have similar defense functions as in they do in mammals, and that the innate immune response in catfish is similar to mammals.
Technical Abstract: Channel catfish were intraperitoneally challenged with the bacterium Edwardsiella ictaluri and the expression of genes presumed to function in the inducible innate defense was evaluated. End binding protein 1 (EB1), Beta1-integrin, natural resistance associated macrophage protein (Nramp), heat shock protein 70 (Hsp70), serum amyloid P (SAP), and transferrin gene expression profiles were determined using quantitative reverse-transcriptase PCR on liver, anterior kidney (AK), spleen and gut. Fish were sub-sampled at 0, 24, 48, 72, and 96 hours post bacterial or phosphate buffered saline (PBS) injection (hpi). Most transcripts were found universally but SAP and transferrin were liver-specific. In bacterially infected fish, expression of EB1 (AK, spleen and liver), Hsp70 (AK and spleen), Beta1-integrin (liver) and Nramp (spleen and gut) significantly increased by 48 hpi. Transferrin was strongly up-regulated and SAP was down-regulated by 72 hpi, suggestive of positive and negative acute phase reactants. The expression patterns of the catfish genes were similar to that expected during bacteremia. This supports the assumption that the products of the catfish genes have similar defense functions as the mammalian counterparts and that the catfish has a similar innate immune response.