Plant & Animal Genomes XV Conference

January 13-17, 2007
Town & Country Convention Center
San Diego, CA

Global Assessment Of The Acute Phase Response In Catfish After Infection With A Gram Negative Bacterium

Eric Peatman , Puttharat Baoprasertkul , Jefferey Terhune , Peng Xu , Samiran Nandi , Huseyin Kucuktas , Ping Li , Shaolin Wang , Benjaporn Somridhivej , Thanathip Lamkom , Wonkyo Lee , Rex Dunham , Zhanjiang Liu

  The Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Aquatic Genomics Unit, Auburn University, Auburn, AL 36849, USA

The acute phase response (APR) is a set of metabolic and physiological reactions occurring in the host in response to tissue infection or injury and is a crucial component of the larger innate immune response. The APR is best characterized by dramatic changes in the concentration of a group of plasma proteins known as acute phase proteins (APP) which are synthesized in the liver and function in a wide range of immune-related activities. Utilizing a second generation high-density in situ oligonucleotide microarray for catfish, we have evaluated for the first time the APR in catfish liver following infection with Edwardsiella ictaluri, a fast-acting Gram negative bacterial pathogen. Our 28K catfish microarray was built upon a previous 19K channel catfish array (Li and Waldbieser 2006) by adding recently sequenced immune transcripts from channel catfish along with 7160 unique sequences from ESC-resistant blue catfish. This dual-species platform allowed a global assessment of the APR in the two closely-related species as well as a comparison of transcriptional differences between species. Analysis of microarray results using a cutoff of two-fold change in gene expression and a 10% false discovery rate revealed a well-developed APR in catfish, with particularly high up-regulation (>50-fold) of genes involved in iron homeostasis (i.e. intelectin, hemopexin, haptoglobin, ferritin, and transferrin). Other classical APP upregulated greater than two-fold included coagulation factors, proteinase inhibitors, transport proteins, and complement components. Up-regulation of the majority of the complement cascade including the membrane attack complex components and complement inhibitors was observed in channel catfish. A number of pathogen recognition receptors (PRRs) and chemokines were also differentially expressed in the liver following infection. Validation with real-time PCR confirmed the microarray results. Efforts to functionally characterize and map many of these important immune components are ongoing. Progress towards this end, along with a comparison of differentially expressed gene profiles between channel and blue catfish, will be presented.