The SS1 virus contains one copy of ICP4 gene under the control of 5xSRE and minimal TATA sequence. (A) Viral genomic PCR reactions confirm the structure of the recombinant ICP4 gene. The sequence for each pair of primer, the relative positions and of the primers as well as their sequence and results are shown. The PCRs were performed on U87 cells (non-transfected), d120-genomic DNA (labeled as d120) and the plasmid pTSIIDT. Performing PCR on back-bone elements of pTSIIDT is done in order to rule out the contamination of genomic viral DNA preparations by pTSIIDT. (B) Genomic structure of HSV-1 and SS1 virus and pTSIIDT plasmid DNA. NotI restriction analysis: The 9.3 Kb NotI fragment contains the plasmid backbone, the 2.8 and 0.7 Kb fragments are the expected digestion pattern from both SS1 and pTSIIDT, which contains the ICP4 gene (arrowheads). Twenty µg DNA of each sample was digested over night at 37°C and resolved in 1% agarose gel. Lane 1:HSV-1/NotI; Lane 2:d120/NotI; Lane 3:SS1/NotI; Lane4: pTSIIDT/NotI; Lane5:DNA marker (from top to bottom: 23, 9.4, 6.6, 4.4, 2.3, 2.0 and 0.5 Kb).