Involvement of selected cellular miRNAs in the in vitro and in vivo infection of infectious salmon anemia virus (ISAV)

Infectious salmon anemia virus (ISAV) is the causative agent of infectious salmon anemia (ISA), a relatively novel disease primarily affecting farmed salmon species, primarily in Salmo salar specimens, causing severe outbreaks in most producer countries. Although ISAV has been extensively studied at the molecular level, not much is known about the host/cell interaction at the small RNA level. MicroRNAs (miRNAs) are small, non-coding RNA that regulate mRNA expression at the post-transcriptional level. In recent years, the putative role of these molecules in host-pathogen interactions has drawn particular attention because of their pivotal involvement as regulatory elements in a number of eukaryotic organisms. Given the importance of the salmon industry in Chile, a deep understanding of the interaction between ISAV and its hosts is of importance. In the present work, we studied the kinetic expression of selected miRNAs during ISAV infection, both in vitro and in vivo. Based on initial experimental data derived from a small RNA-Seq analysis, a group of miRNAs that were differentially expressed in infected cells were selected for analysis. As a result, two miRNAs, miR-462a-5p and miR-125 b-5p, showed increased and decreased expression, respectively, during ISAV infection.