Genome-wide identification and evolution of interleukins and their potential roles in response to GCRV and Aeromonas hydrophila challenge in grass carp (Ctenopharyngodon idella)

Abstract

Interleukins (ILs) play important roles in transmitting information, mediating proliferation and differentiation of immune cells, and regulating immune responses. However, due to the large variety, number, and complexity of IL genes, complete and systematic studies on ILs remain largely unknown. In the present study, we identified and characterized 39 IL genes in grass carp (Ctenopharyngodon idella) based on genomic and transcriptomic datasets. These IL genes were classified into six gene families and others. Gene structures, conserved domains, and motif analyses indicated that ILs in the same gene family were more conserved. Collinearity analysis showed that the segmental duplication events played a critical role in the expansion of IL gene families during evolution. RNA-seq data from different healthy tissues showed that many IL genes were widely expressed in various tissues. Based on RNA-seq data, we further analyzed the expression profiles of IL genes in tissues post grass carp reovirus (GCRV) or Aeromonas hydrophila challenge, and the results showed that the expressions of some genes were significantly upregulated or downregulated post-challenge. Finally, qRT-PCR verified mRNA expressions of the representative IL genes post GCRV or A. hydrophila challenge. Taken together, these studies provide a theoretical basis for a comprehensive understanding of ILs and further functional investigation.