Fig. 1.

Consequence of modulation of the T cell repertoire during heterologous viral infections: The dots represent CD8 T cell populations that have different specificities. The naïve T cell repertoire encounters virus A (blue) and virus A-specific CD8 T cells expand and maintain into memory. If this memory T cell pool is exposed to an unrelated virus B (green), memory CD8 T cells that are cross-reactive will preferentially expand and dominate the response whereas non cross-reactive CD8 T cells specific for the first virus decrease in number. The now dominant cross-reactive CD8 T cells can participate in immunopathology and partial protective immunity.