FIG. 2.

Detection of an additional protective CD8⁺-T-cell epitope in M84. Diagrams above panels A and B represent wild-type M84, IE1, and their mutant proteins, M84ΔKd and pp89ΔLd. The known CD8⁺-T-cell epitopes 297-305 (M84) or 168-176 (IE1) are indicated. They were deleted in M84ΔKd and pp89ΔLd. The numbers represent the amino acid position in the protein. BALB/c mice were immunized i.d. three times with DNA vaccines pc3Δneo (vector), pc3-M84, pc3-M84ΔKd, pc3-pp89, or pc3-pp89ΔLd. Ten days after the last immunization, three mice per group were examined for M84-specific CD8⁺ T cells by using a peptide-mediated or M84-expressing-J774 cell-mediated ICCS assay. The other four mice per group were challenged i.p. with 3.5 × 10⁵ PFU (0.5 LD₅₀) of salivary gland-derived MCMV (A and B). Five days later, the virus titer in the spleen was examined (C). (A) M84-specific CD8⁺-T-cell responses measured with ICCS assay by using M84 297-305 peptide (left three columns) or M84-expressing-J774 cells (right three columns) as a stimulator. (B) The IE1-specific CD8⁺-T-cell responses measured with ICCS with IE1 168-176 peptide (left three columns) or IE1-expressing-J774 cells as a stimulator. (C) Titer of MCMV per spleen after challenge of immunized mice. Solid symbols stand for measurement of CD8⁺-T-cell responses or virus titers in individual mice.