CD4 and infection: At 1 (panel B) or 2 (panel C) weeks after infection, splenocytes from infected mice had significantly higher frequencies of human CD45+ cells (n = 14 mice), human CD4+ cells (n = 6 at week 1 and n = 14 at week 2) and human CD8 (n = 9 at week 1 and n = 10 at week 2) T cells that produced IFN-γ in response to stimulation with DENV-2 antigen compared to the control antigen (Fig. 6B and C).