CD8A and infection: As expected, mice vaccinated with MCMV-M or MCMV-M2 alone mounted immunodominant CD8+ T cell responses to the corresponding vaccine antigens, whereas mice vaccinated with both MCMV-M and MCMV-M2 displayed very high frequencies of M-specific CD8+ T cells relative to M2-specific CD8+ T cells, inverting the natural immunodominance hierarchy observed after infection with RSV.