Here we look at the changes in MUP output with time after adoptive CTL transfer in v2.2 persistently infected mice (inoculated within 18 h of birth) and compare this with output after adult infection with v2.2 (which stimulates a natural CD8 CTL response and recovery) or with v54 (no virus-specific CD8 CTL response leading to persistent infection) among males of matched age (Figure 3). Here, CD8A is linked to infection.