Characterization of cellular immune responses raised against CPS-CRM197, Hcp1, and TssM. C57BL/6 mice (n = 4 per group) were immunized on days 0, 21, and 35 with adjuvant only (Alhydrogel/CpG), conjugate only, Hcp1 only, TssM only, conjugate plus Hcp1, or conjugate plus TssM. Spleens were harvested on day 42, and IFN-γ-secreting T cell responses against (a) CPS-CRM197, (b) Hcp1, and (c) TssM were quantitated in an ELISpot assay. Black dots represent the mean results of assays conducted in duplicate for individual mice. Black bars represent geometric means for a group. ns, not significant; *, P < 0.05.