Expression and function of microRNAs in viruses great and small.

Since they employ host gene expression machinery to execute their genetic programs, it is no surprise that DNA viruses also encode miRNAs. The small size of viral genomes, and the high degree of understanding of the functions of their gene products, make them particularly favorable systems for the examination of miRNA biogenesis and function. Here we review our computational and array-based approaches for viral miRNA discovery, and we discuss the structure and function of miRNAs identified by these approaches in polyomaviruses and herpesviruses.