Private specificities of CD8 T cell responses control patterns of heterologous immunity

Kim, Sung-Kwon; Cornberg, Markus; Wang, Xiaoting Z.; Chen, Hong D.; Selin, Liisa K.; Welsh, Raymond M.

However, in most of our previous studies, we analyzed the impacts of heterologous virus infections simply by comparing the LCMV-specific CD8 T cells between separate groups of LCMV-immune control mice and LCMVimmune mice infected with heterologous viruses. We questioned here whether individual mice could differ dramatically in the patterns of their cross-reactivities to heterologous viruses and sought to compare epitope-specific responses after a heterologous viral infection to the hierarchy of the T cell repertoire in the LCMV-immune mouse before the heterologous viral challenge. To address these issues of immune responses unique to the individual, we adopted a longitudinal analysis method to reiterate the impacts of heterologous PV or VV infections on LCMV-immune mice. First, we exam- ined the frequency and the hierarchy of LCMV-specific CD8 T cells in the peripheral blood of individual LCMV-immune mice before (day 0) PV or VV infection and then at late stages of the heterologous viral challenge (Fig. 1, A and B , day 12). A peptide epitope-induced intracellular IFN-␥ assay was used to identify and quantify epitope-specific T cells.