Comparison of CD4⁺ T cells from the jejunum of neonates. Expression of both CD25 and CD69 (A), CD69 alone (B), or CD25 alone (C) in SIV-infected neonates (solid lines) was compared with age-matched controls (dotted lines). Note that there is a marked and selective loss of activated (CD25⁺ and/or CD69⁺) cells in the intestine of all SIV-infected neonates by 12 days of infection.