FIG. 5.

Chronic infection prevents the establishment of memory CD4 T-cell responses. A. Mice that had been previously infected with Armstrong (gray bars) or Clone 13 (black bars) were either left alone (left bars in each panel) or were rechallenged (right bars in each panel) with Clone 13. After 3 days, the livers of individual mice were isolated, and the number of SMARTA cells (left panel) was determined. IFN-γ (middle panel) and TNF-α (right panel) production were assessed by intracellular flow cytometry. Values represent the average ± standard deviation of three to four mice in each group.