Functional CD8 T cell memory responding to persistent latent infection is maintained for life.

There were no significant differences in the percentages and numbers of epitope-specific tetramer+ memory CD8 T cells between adult (6 months post-infection) and old (20 months post-infection), both in blood and spleen. Expression of KLRG1 by both adult and old memory cells was high, suggesting that a large proportion (40–60% in spleen, 50–80% in blood) of the epitope-specific CD8+ T cell memory pool may be unable to proliferate in response to stimulation.