CD8A and infection: Based on the differentiation markers CD45RO and CCR7, we defined naïve (CCR7+, CD45RO-), central memory (Tcm, CCR7+, CD45RO+), effector memory (Tem, CCR7-, CD45RO+), and TEM/TEMRA (Tem/Temra, CCR7-, CD45RO-) subsets of bulk CD8+ T cells and HCV-specific CD8+ T cells at different stages of infection.