How viruses interfere with interferon

Double-stranded RNA is a warning flag to the cell, indicating the presence of a virus. In 2004, Takashi Fujita and colleagues at Tokyo Metropolitan Institute of Medical Science identified an RNA-helicase, retinoic acid inducible gene I (RIG-I), as linking dsRNA and the interferon response.1 In the same year, Richard Randall at the University of St. Andrews in Scotland and his group revealed that the V protein of paramyxoviruses short-circuits the interferon response by binding mda-5, a similar RNA helicase, not previously linked with interferon production.2

Robert Lamb at Northwestern University in Evanston, Ill., says that as a consequence, "investigations are being conducted on just about every virus as to interactions with mda-5 and RIG-I."

Questions remain. While dsRNA can activate both mda-5 and RIG-I, Randall says it's unclear whether they recognize slightly different forms of dsRNA or other viral structures. "Also, it needs to be established whether or...