CD8A and infection: We noted a number of mid-aged and aged individuals with frequencies of CMV-reactive CD8+ T cells that represented more than 9% (9 subjects) of the circulating CD8+ T cell pool, but we did not observe any relationship between expanded CMV-specific CD8+ T cells and impaired generation of WNV-specific CD8+ T cells, indicating that CMV expansions do not limit the ability of the host to respond to a novel infection, consistent with the report of Vezys et al. [26].