Comprehensive identification and profiling of host miRNAs in response to Singapore grouper iridovirus (SGIV) infection in grouper (Epinephelus coioides)

• miRNAs profile of grouper was performed by Solexa deep sequencing and microarray.
• A total of 107 conserved and 9 novel miRNAs were identified.
• Many miRNAs were differentially regulated during SGIV infection in vivo and in vitro.
• Target prediction indicated that a number of miRNAs involved in immunity.

microRNAs (miRNAs) are an evolutionarily conserved class of non-coding RNA molecules that participate in various biological processes. Employment of high-throughput screening strategies greatly prompts the investigation and profiling of miRNAs in diverse species. In recent years, grouper (Epinephelus spp.) aquaculture was severely affected by iridoviral diseases. However, knowledge regarding the host immune responses to viral infection, especially the miRNA-mediated immune regulatory roles, is rather limited. In this study, by employing Solexa deep sequencing approach, we identified 116 grouper miRNAs from grouper spleen-derived cells (GS). As expected, these miRNAs shared high sequence similarity with miRNAs identified in zebrafish (Danio rerio), pufferfish (Fugu rubripes), and other higher vertebrates. In the process of Singapore grouper iridovirus (SGIV) infection, 45 and 43 miRNAs with altered expression (>1.5-fold) were identified by miRNA microarray assays in grouper spleen tissues and GS cells, respectively. Furthermore, target prediction revealed 189 putative targets of these grouper miRNAs.