Background:The Pacific white shrimp,Litopenaeus vannamei,is a worldwide cultured crustacean species with important commercial value.Over the last two decades,Taura syndrome virus(TSV)has seriously threatened the shrimp aquaculture industry in the Western Hemisphere.To better understand the interaction between shrimp immune and TSV,we performed a transcriptome analysis in the hepatopancreas of L.vannamei challenged with TSV,using the 454 pyrosequencing(Roche)technology.Methodology/Principal Findings:We obtained 126919 and 102181 high-quality reads from TSV-infected and non-infected(control)L.vannamei cDNA libraries,respectively.The overall de novo assembly of cDNA sequence data generated 15004 unigenes,with an average length of 507bp.Based on BLASTX search(E-value,1025)against NR,Swissprot,GO,COG and KEGG databases,10425 unigenes(69.50%of all unigenes)were annotated with gene descriptions,gene ontology terms,or metabolic pathways.In addition,we identified 770 microsatellites and designed497 sets of primers.Comparative genomic analysis revealed that 1311 genes differentially expressed in the infected shrimp compared to the controls,including 559 up-and 752 down-regulated genes.Among the differentially expressed genes,several are involved in various animal immune functions,such as antiviral,antimicrobial,proteases,protease inhibitors,signal transduction,transcriptionalcontrol,celldeath and celladhesion.Conclusions/Significance:This study provides valuable information on shrimp gene activities against TSV infection.Results can contribute to the in-depth study of candidate genes in shrimp immunity,and improves our current understanding of this host-virus interaction.In addition,the large amount of transcripts reported in this study provide a rich source for identification of novel genesin shrimp. Background: The Pacific white shrimp, Litopenaeus vannamei, is a worldwide cultured crustacean species with important commercial value. Over the last two decades, Taura syndrome virus (TSV) has severely threatened the shrimp aquaculture industry in the Western Hemisphere. To better understand the interaction between shrimp immune and TSV, we performed a transcriptome analysis in the hepatopancreas of L. vannamei challenged with TSV, using the 454 pyrosequencing (Roche) technology. Methodology / Principal Findings: We obtained 126919 and 102181 high-quality reads from TSV-infected and non-infected (control) L. vannamei cDNA libraries, respectively. The overall de novo assembly of cDNA sequence data generated 15004 unigenes, with an average length of 507 bp. Based on BLASTX search (E-value, 1025) against NR, Swissprot, GO, COG and KEGG databases, 10425 unigenes (69.50% of all unigenes) were annotated with gene descriptions, gene ontology terms, or metabolic pathways. Addition, we identified 770 microsatellites and designe d497 sets of primers. Comparative genomic analysis revealed that 1311 genes differentially expressed in the infected shrimp compared to the controls, including 559 up-and 752 down-regulated genes. Among the differentially expressed genes, several are involved in various animal immune functions, such as antiviral, antimicrobial, proteases, protease inhibitors, signal transduction, transcriptional control, celldeath and celladhesion. Conclusions / Significance: This study provides valuable information on shrimp gene activities against TSV infection. Results contribute to the in-depth study of candidate genes in shrimp immunity, and improves our current understanding of this host-virus interaction. addition, the large amount of transcripts reported in this study provide a rich source for identification of novel genesin shrimp.