To establish whether HCMV latent and lytic protein specific T cells are maintained and are functional during long-term carriage of the virus, we analyzed T cell responses to five viral genes known to be expressed during HCMV latent infection: UL138 (38), LUNA (39, 40), US28 (41), UL111A (vIL-10) (42), and UL144 (43), two of which (UL138 and LUNA), we have previously shown elicit both an IFNγ and IL-10 CD4+ T cell response (53). This evidence concerns the gene IL10 and disease arising from reactivation of latent virus.