Targeting host DEAD-box RNA helicase DDX3X for treating viral infections.

DDX3X or DDX3, a member of the DEAD (asp, glu, ala, asp) box RNA helicase family of proteins, is a multifunctional protein, which is usurped by several viruses and is vital to their production. To date, 18 species of virus from 12 genera have been demonstrated to be dependent on DDX3 for virulence. In addition, DDX3 has been shown to function within 7 of 10 subcellular regions that are involved in the metabolism of viruses. As such, due to its direct interaction with viral components across most or all stages of viral life cycles, DDX3 can be considered an excellent host target for pan-antiviral drug therapy and has been reported to be a possible broad-spectrum antiviral target. Along these lines, it has been demonstrated that treatment of virally infected cells with small molecule inhibitors of DDX3 blunts virion productions. On the other hand, DDX3 bolsters an innate immune response and viruses have evolved capacities to sequester or block DDX3, which dampens an innate immune response. Thus, enhancing DDX3 production or co-targeting direct viral products that interfere with DDX3's modulation of innate immunity would also diminish virion production. Here we review the evidence that supports the hypothesis that modulating DDX3's agonistic and antagonistic functions during viral infections could have an important impact on safely and efficiently subduing a broad-spectrum of viral infections.