MicroRNAs as mediators of viral evasion of the immune system

Abstract

Cellular microRNAs serve key roles in the post-transcriptional regulation of almost every cellular gene-regulatory pathway, and it therefore is not surprising that viruses have found ways to subvert this process. Several viruses encode microRNAs that directly downregulate the expression of factors of the innate immune system, including proteins involved in promoting apoptosis and recruiting effector cells of the immune system. Viruses have also evolved the ability to downregulate or upregulate the expression of specific cellular miRNAs to enhance their replication. This Review provides an overview of the present knowledge of the complex interactions of viruses with the microRNA machinery of cells.

Figure 1. Schematic representation of the genome structure of the human herpesviruses EBV, KSHV and HCMV

This figure provides an overview of the repeat elements and viral miRNAs present in these viruses.

Figure 2. Sequence alignment of miR-155 with viral mRNA mimics

Alignment of human (hs) and chicken (gga) miR-155 with the sequences of the viral miR-155 mimics KSHV miR-K11 and MDV-1 miR-M4.