CD8A and infection: After three vaccinations, the PrS5E, Pr4LS5E, pHyb, and PrMVA13.5-long promoters showed higher levels of OVA- specific CD8 T cells compared to those observed for B8R, a vector derived antigen that is also expressed early during infection [30,31] and is highly immunodominant in VACV infected C57BL/6 mice [41].