αTub84B promoter sequences drive expression of an infection-inducible form of GAL4. The construct encodes a fusion protein consisting of the first two transmembrane helices of lbm and the complete coding region of GAL4, separated by the VP4B-VP4C junction protease cleavage site of the Nora virus genome. In the absence of infection, the lbm sequence tethers the GAL4 protein to the plasma membrane, rendering it inactive. Upon infection of the animal with Nora virus, the fusion protein is cleaved by the viral protease, releasing the GAL4 protein so that in can enter the nucleus and drive transcription.