Whereas we focused here on functional cells defined by their ability to secrete IFNγ after stimulation with the cognate antigenic peptide, an independent previous experiment revealed 2-4-fold higher frequencies of CD8 T cells carrying IE1- or m164-specific TCRs, compared to functionally defined frequencies, and a subset distribution that varied in the time course after infection (S3 Fig). The gene discussed is CD8A; the disease is infection.