A 926bp SpeI fragment from sv (which includes the "spa" enhancer) and a 300bp promoter region and 289bp adjacent leader of sv are fused upstream of a 1.73kb fragment which includes the Poxn P4c6 cDNA.
Flies carrying two copies of Poxnsv.PJ in a svspa-pol/+ background have a weak rough eye phenotype, which is stronger in a homozygous svspa-pol background.