FIG. 2.

SDV replicons and infectious cDNA constructs. (A) Hammerhead ribozyme nucleotide sequence. The BamHI and NaeI restriction enzyme sites and the T7 promoter sequence are underlined. The ribozyme cleavage site and the beginning of the SDV genome are indicated by arrows. (B) The entire SDV cDNA was transferred from the pBluescript backbone into a pcDNA3 plasmid and fused to the hammerhead ribozyme sequence (HH) (see Materials and Methods). The gene encoding the structural protein was removed by BlpI/EcoRV restriction enzyme digestion and replaced by the reporter gene LUC (pnsP-Luc) or GFP (pnsP-GFP). (C) The LUC gene was removed from the pnsP-LUC construct and exchanged with structural (Struct.) genes by BlpI and EcoRV restriction enzyme digestion and ligation. A T7 terminator sequence (T7t) was added downstream of the poly(A) tail (pA), yielding the final construct, pSDV.