Interferon-γ ELISpot. BALB/C or C57BL/6 mice were immunized three times, each two weeks apart, with 100ug pVAX vector or pM and sacrificed one week later. Splenocytes were harvested and cultured overnight in the presence of R10 (negative control) or 10μg/mL of one of two peptide pools, made up of 15-mer peptides overlapping by 11 amino acids, spanning the length of the matrix 1 antigen. Also shown are CD8-depleted controls. Spot forming units were quantified by an automated ELISPOT reader, and the raw values were normalized to SFU per million splenocytes. Values represent the mean (±SD) of triplicate wells.