Transcriptome profiles of the clam Meretrix petechialis hepatopancreas in response to Vibrio infection.

Microbial diseases have received much attention due to their enormous destruction of aquaculture, and Vibrio parahaemolyticus is one of the main pathogens that cause bacterial disease in the clam Meretrix petechialis. To better understand the molecular mechanisms of the immune response to Vibrio in M. petechialis, RNA-Seq was applied to explore global expression changes of hepatopancreas from this clam after Vibrio challenge. There were 199,318,966 clean reads obtained by Illumina sequencing, which were further assembled into 214,577 transcripts, and then 147,255 unigenes with an N50 of 1393 bp were identified. Gene ontology (GO) analysis revealed 21 biological process subcategories, 15 cellular component subcategories and 12 molecular function subcategories. A total of 8358 unigenes were mapped onto 267 biological signaling pathways by KEGG, among which there were 16 pathways related to the immune system. In total, 206 differentially expressed genes (DEGs) were identified, including 113 up-regulated unigenes and 93 down-regulated unigenes. In these DEGs, 96 DEGs were annotated in at least one database, accounting for 46.60% of all significant DEGs. To validate the transcriptome dataset, 15 DEGs were selected for real-time qPCR confirmation and the results showed that expression patterns of 13 genes (86.7%) agreed well with the RNA-Seq analysis. Fourteen of the 206 DEGs were annotated to be immune-related genes, and we examined the expression patterns of four immune-related DEGs using clams post immersion challenge. This study enriched the M. petechialis transcriptome database and provided insight into the immune response of M. petechialis against Vibrio infection.