Role of virus-encoded microRNAs in herpesvirus biology

MicroRNAs (miRNAs) are short RNAs of about 22 nucleotides in length that post-transcriptionally regulate gene expression by binding to 3' untranslated regions of mRNAs, thereby inducing translational silencing. Recently, more than 140 miRNAs have been identified in the genomes of herpesviruses. Deciphering their role in viral biology requires the identification of target genes, a challenging task because miRNAs require only limited complementarity. The subject of this review will be the herpesvirus miRNAs and their respective target genes that have been determined experimentally to date. These miRNAs regulate fundamental cellular processes including immunity, angiogenesis, apoptosis, and key steps in the herpesvirus life cycle, latency and the switch from latent to lytic replication.