Reverse Genetics Modification of Cytomegalovirus Antigenicity and Immunogenicity by CD8 T-Cell Epitope Deletion and Insertion

Figure 2

Loss-of-presentation mutagenesis of antigenic peptides. (Top) Genome size scale of mCMV and bidirectional gene pair architecture of the major immediate-early (MIE) locus, with the promoter-enhancer-enhancer-promoter (PEEP) region flanked to the left by the ie1/3 transcription unit (ORFs m123/M122) and to the right by gene ie2 (ORFm128) [86]. Exons are symbolized by boxes, with blue boxes representing the four exons specifying the IE1 mRNA. The coding sequence for the antigenic IE1 peptide is located in exon 4. (Center) Nucleotide and corresponding amino acid sequences for the authentic and mutated IE1 peptides, with mutations being highlighted in red. (Bottom) Artwork models illustrating the binding of authentic and mutated IE1 peptides to the presenting MHC class-I molecule H-2-L^d through the C-terminal anchor residue. The mutation is highlighted in red. L176A: mutant; A176L: authentic revertant; A176L*: “wobble” revertant maintaining a single nucleotide polymorphism as a genetic marker distinguishing it from WT and authentic revertant.