Expression analysis of selected immune-relevant genes in channel catfish during Edwardsiella ictaluri infection.
Channel catfish Ictalurus punctatus were intraperitoneally challenged with the bacterium Edwardsiella ictaluri (the causative agent of enteric septicemia of catfish), 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-polymerase chain reaction on liver, anterior kidney, spleen, and gut. Fish were subsampled at 0, 24, 48, 72, and 96 h after bacterial or phosphate-buffered-saline injection. Posterior kidney sampling demonstrated increasing bacterial counts at 24-48 h postinjection (hpi), followed by a plateau to 96 hpi. The transferrin and SAP transcripts were liver specific. The other genes were expressed in all four tissues. In bacterially infected fish, expression of EB1 (anterior kidney, spleen, and liver), Hsp70 (anterior kidney and spleen), and Nramp (spleen and gut) significantly increased by 48 hpi. Transferrin was strongly up-regulated and SAP was downregulated by 72 hpi, indicating positive and negative acute-phase reactants, respectively. The data indicate a substantial response of innate immunity effector cells by 48 hpi, followed by suppression of bacterial growth and induction of the acute-phase response. This suggests that the 48-72-hpi time frame is critical in our model for evaluating the effectiveness of innate defenses.
Elibol-Flemming
Banu
B
Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi 39762, USA.
Waldbieser
Geoffrey C
GC
Wolters
William R
WR
Boyle
Carolyn R
CR
Hanson
Larry A
LA
D000818:Animals; D020610:Edwardsiella ictaluri; D004756:Enterobacteriaceae Infections / Q000276:immunology / Q000378:metabolism / Q000662:veterinary*; D005393:Fish Diseases / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000276:immunology*; D007059:Ictaluridae / Q000276:immunology*; D008099:Liver / Q000378:metabolism; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000378:metabolism
D029941:Fish Proteins