Immune gene discovery by expressed sequence tag analysis of spleen in the duck (Anas platyrhynchos)

To search for immune relevant genes of the duck we have conducted an expressed sequence tag (EST) project. Duck immune genes are relevant to disease resistance in agriculture and in intervention in avian influenza outbreaks through vaccination of ducks. We sequenced 3168 clones from a spleen cDNA library of a White Pekin duck, Anas platyrhynchos. We constructed an EST analysis pipeline enabling (1) quality checking and clustering, (2) identification based on BLAST results, (3) annotation using Gene Ontology, and (4) submission to the dbEST database. In total, 208 genes were relevant to the duck immune system, which we have divided into categories: (1) leukocyte receptors, (2) lectin-like immunoreceptors, (3) cytokines and chemokines, (4) transcription factors (5) mediators of antigen processing or apoptosis, and (6) innate effectors. We compared 425 homologous sequences between the duck and the closest genetic model organism, chicken. Homologous genes had regions sharing 80 to 99 percent nucleotide identity, however immune-relevant genes were less conserved than other genes.