Identification of immune-related genes in hemocytes of black tiger shrimp (Penaeus monodon).

An expressed sequence tag (EST) library was constructed from hemocytes of the black tiger shrimp (Penaeus monodon) to identify genes associated with immunity in this economically important species. The number of complementary DNA clones in the constructed library was approximately 4 x 10(5). Of these, 615 clones having inserts larger than 500 bp were unidirectionally sequenced and analyzed by homology searches against data in GenBank. Significant homology to known genes was found in 314 (51%) of the 615 clones, but the remaining 301 sequences (49%) did not match any sequence in GenBank. Approximately 35% of the matched ESTs were significantly identified by the BLASTN and BLASTX programs, while 65% were recognized only by the BLASTX program. Of the 615 clones, 55 (8.9%) were identified as putative immune-related genes. The isolated genes were composed of those coding for enzymes and proteins in the clotting system and the prophenoloxidase-activating system, antioxidative enzymes, antimicrobial peptides, and serine proteinase inhibitors. Three full-length ESTs encoding antimicrobial peptides (antilipopolysaccharide and penaeidin homologues) and a heat shock protein (cpn10 homologue) are reported.