Novel microRNA-like viral small regulatory RNAs arising during human hepatitis A virus infection

MicroRNAs (miRNAs), including host miRNAs and viral miRNAs, play vital roles in regulating host-virus interactions. DNA viruses encode miRNAs that regulate the viral life cycle. However, it is generally believed that cytoplasmic RNA viruses do not encode miRNAs, owing to inaccessible cellular miRNA processing machinery. Here, we provide a comprehensive genome-wide analysis and identification of miRNAs that were derived from hepatitis A virus (HAV; Hu/China/H2/1982), which is a typical cytoplasmic RNA virus. Using deep-sequencing and in silico approaches, we identified 2 novel virally encoded miRNAs, named hav-miR-1-5p and hav-miR-2-5p. Both of the novel virally encoded miRNAs were clearly detected in infected cells. Analysis of Dicer enzyme silencing demonstrated that HAV-derived miRNA biogenesis is Dicer dependent. Furthermore, we confirmed that HAV mature miRNAs were generated from viral miRNA precursors (pre-miRNAs) in host cells. Notably, naturally derived HAV miRNAs were biologically and functionally...