Identification of immune relevant genes using expressed sequence tags (ESTs) in common carp (Cyprinus carpio) gills and intestine

Identification of immune related molecules that function in fish organs is important for better understanding of the host defense mechanisms in fish. Expressed sequence tags (ESTs) represent the expressed portion of a genome, so they have proven to be useful tool for gene identification and confirmation of gene predictions. In the present study, a transcriptome analysis of carp gill and intestine EST libraries have been done as an attempt to identify the immune relevant genes expressed in those organs. A total of 2148 EST clones were generated from the two libraries: 1099 clones from gill library in which 632 clones were matched with functional proteins and 1049 clones from intestine library in which 559 clones were matched with functional proteins. The results of gill EST library has more frequency of innate immune-molecules containing MHC class I and MHC class II, which showed 18.3% of the immune molecules than those in intestine library which represents 10.8% only. The gill library also showed higher frequency of the cytokines and chemokine molecules and/or their receptors compared to the intestine library.