Cytomegalovirus infection induces T‐cell differentiation without impairing antigen‐specific responses in Gambian infants

SummaryCytomegalovirus (CMV) infection induces profound differentiation of T cells, and is associated with impaired responses to other immune challenges. We therefore considered whether CMV infection and the consequent T‐cell differentiation in Gambian infants was associated with impaired specific responses to measles vaccination or polyclonal responses to the superantigen staphylococcal enterotoxin B (SEB). While the concentration of undifferentiated (CD27+ CD28+ CCR7+) T‐cells in peripheral blood was unaffected by CMV, there was a large increase in differentiated (CD28− CD57+) CD8 T‐cells and a smaller increase in differentiated CD4 cells. One week post‐vaccination, the CD4 cell interferon‐γ (IFN‐γ) response to measles was lower among CMV‐infected infants, but there were no other differences between the cytokine responses, or between the cytokine or proliferative responses 4 months post‐vaccination. However, the CD8 T cells of CMV‐infected infants proliferated more in response to SEB and the antibody response to measles correlated with the IFN‐γ response to CMV, indicating that CMV infection actually enhances some immune responses in infancy.