Fig. 1.

Schematic representation of RNA Kunjin replicon constructs encoding the SIV gag and gag-pol antigens. The Kunjin replicon RNA contained the SP6 RNA promoter, the 5′ and 3′ untranslated regions (UTR), the first 20 amino acids of the Kunjin core protein (C20), ubiquitin (Ub) to allow N-terminal cleavage by ubiquitin hydrolase, the SIV gag or gag-pol genes, the 2A autoprotease sequence of the foot and mouse disease virus (FMDV2A) to allow C-terminal cleavage, the last 22 amino acids of the Kunjin envelope protein (E22), the non-structural proteins (NS1-NS5) that are responsible for RNA replication, the anti-genomic sequence of the hepatitis delta virus ribozyme (HDVr) and the polyadenylation signal from simian virus 40 (pA) [12]. The wild type vaccine construct (WT) contains the full-length native SIV mac239 gag gene. The DX and OPT constructs contain RNA- and codon-optimised versions of this gene, respectively, with the positions of the codon changes schematically represented by vertical lines below the gene box. DX sequence was provided by Dr. Felber and 6% of nucleotides have been changed. The OPT sequence is available from the AIDS Research and Reference Reagent Program web site (catalogue #9422) and 25% of nucleotides have been changed. The Gag-pol construct contains wild-type matrix and capsid from gag and in-frame reverse transcriptase from pol. The gag-pol construct contained a second FMDV2A site in place of the Ub sequence at the N-terminus of gag.