Now you see me, now you don't: What and how viral RNAs are detected by cytoplasmic pattern-recognition receptors.

In a recent issue of Molecular Cell, Genoyer et al.1 show that during West Nile virus infection, escaped, cytoplasmic, anti-genomic negative-sense viral RNA triggers an antiviral response via RIG-I activation. Flaviviruses typically hide -vRNA in replication compartments to avoid detection, but some -vRNA leaks, possibly aided by viral capsid proteins.