FIG 1.
Identification of MCMV-specific CD4 T cells. (A) BALB/c mice were infected with MCMV, and day 8 postinfection, CD4 T cells from the spleens were purified for screening of 24 peptide pools (10 peptides/pool; 10 μg/ml each peptide). The mean numbers of SFC per 106 CD4 T cells from four independent experiments are shown. Responses were considered positive if the stimulation index (SI) exceeded twice the mean of the negative-control wells (effectors plus APCs without peptide) and the net numbers of spots were above the threshold of 100 SFC/106 CD4 cells in each individual experiment (indicated by the dashed line). Positive pools (*) and pools showing an SI of >2 in at least two experiments (arrows) were deconvoluted. (B) Out of all individually tested peptides, two 15-mers were identified (*) that elicited a significant IFN-γ response. They were m53285–99 (IAHQRITLTARCLRL) and m78417–31 (SQQKMTSLPMSVFYS). (C) Splenocytes from day 8 MCMV-infected BALB/c mice were restimulated with m78 or m53 peptide epitopes, and intracellular cytokine staining for IFN-γ and TNF-α was performed. (D) ELISPOT analysis for IFN-γ production by CD4 T cells from day 28 (d28) MCMV-infected mice after restimulation with m53- and m78- peptide epitopes (means of the results of two independent experiments are shown). The data represent means and SEM.