Differential gene expression profile of the hepatopancreas of white spot syndrome virus infected Fenneropenaeus indicus by suppression subtractive hybridization

Suppression Subtractive Hybridization was employed in order to identify the differentially expressed genes in the hepatopancreas of white spot syndrome virus infected Fenneropenaeus indicus. A forward subtracted cDNA library generated 356 clones following a white spot syndrome virus infection. A total of 345 clones with more than 100 nucleotides were selected for further analysis using bioinformatics tools after vector screening. Twenty-three contigs and 111 singletons were generated from a total of 134 consensuses. The consensuses, on a sequence homology search using BLASTX (NCBI), revealed that 74 (55%) of them had no significant match to reported sequences in the database, suggesting that they were found for the first time and are probably associated with shrimp immune function. Out of the remaining 60 (45%) consensuses, 43 had significant homology to known protein sequences in the database while 17 consensuses are homologous to unknown proteins in the database which are considered novel. The most abundant genes in the subtracted library were antimicrobial peptides accounting for 56 clones; among which one is a member of SNF2 family of proteins and another belonged to PfP1 family of proteins on analysis using Antimicrobial peptide predictor software. The other predicted genes in the subtracted library include signal transduction molecules (GTPase, Serine threonine kinase, Armadillo repeats etc), antioxidant enzymes (Cytochrome oxidase, Monomeric sarcosine oxidase and Catalase), active transporters (Nuclear Localization Signal [NLS], calcium ATPase, sodium glutamate symporter, Store-Operated Calcium Entry [SOCE] and ribonucleoprotein [RNP]) contributing to 19, 14 and 5 clones respectively. Three clones are homologous to reverse transcriptase; a first time report in shrimp and one each belong to cell adhesion molecule and Proteinase. InterProScan at EMBL, when used for an integrated search at PROSITE predicted; signal sequences and transmembrane regions for 13 clones. This is the first report on the differential gene expression in WSSV-infected F. indicus. The high expression of immune related genes in response to virus infection in shrimp will provide a new insight into the crustacean innate immunity. Further work on the functionality of the unknown genes in shrimps will give an overview on the role of the differentially expressed genes during viral infection and increase our understanding for developing antiviral measures by making use of the shrimp defense mechanism.