In order to follow antigen-specific T cells, Ly5.1+ TCR transgenic CD8+ and CD4+ T cells specific for the immuno-dominant gp33 (P14) or gp61 (Smarta) peptides were transferred into wild-type (WT) C57BL/6 mice prior to LCMV clone 13 infection. The gene discussed is CD8A; the disease is infection.