New virus discovery by deep sequencing of small RNAs

Small RNAs (sRNAs) have emerged as one of the most important regulators of gene expression in eukaryotes. sRNAs are intermediate molecules as well as end products in the antiviral defense pathway called RNA interference in plants and animals. Profiling of sRNAs using next-generation sequencing technologies has identified a number of plant viruses that have never been reported previously, and has provided a deeper view of virus populations in a plant that cannot be achieved by conventional methods like PCR and ELISA. In this chapter, we describe the methodology of deep sequencing of sRNAs. The high-throughput and highly sensitive method will revolutionize the identification of plant viruses and the study of molecular plant-virus interactions.