Double-Stranded RNA Pull-Down to Characterize Viral Replication Complexes in Plants.

Plant RNA viruses are obligate intracellular parasites that hijack specific cellular membranes to replicate their genomes in what are commonly known as viral replication complexes (VRC). These contain host- and virus-encoded proteins and viral RNA. Double-stranded RNA (dsRNA) is a mandatory intermediate of RNA replication and a hallmark feature of VRCs. We have recently developed a method to isolate viral dsRNA and its associated proteins through pull-down of an ectopically expressed dsRNA-binding protein (B2:GFP) from infected Arabidopsis thaliana plants. After mass spectrometry analysis to identify the dsRNA-associated proteins, resulting candidate proteins of interest are tagged with a red fluorescent protein and their subcellular localization in relation to VRCs is assessed by transient expression within leaves of B2:GFP-transgenic Nicotiana benthamiana plants. In this chapter we describe in detail these experimental procedures to allow investigators to characterize the replication complexes of their plant RNA virus of interest.