Constructs used for making DNA vaccines. (A) The HPV-16 E7 gene was cleaved at the positions corresponding to the pRB binding site and in between the two Cys-XX-Cys motifs. The cleavage points between amino-acid numbers are shown above the gene. The resulting fragments were rearranged (“shuffled”) forming the core-element, and an appendix containing the junctions where the cleavage took place was added to avoid loss of putative CTL epitopes to form 16E7SH. (B) Depiction of the 7 constructs utilised in this study. The core genes and fusions of genes were cloned into the respective pTH or pTRAc expression vectors.