In an effort to control for potential differences in infection-induced inflammatory microenvironments that can develop and therefore influence primary and secondary T cell responses that are generated in separate hosts, naïve B6 (Thy1.2+) recipient mice were adoptively transferred with enriched CD4 T cells obtained from B6 (Thy1.1+) donors that had been previously infected with LCMV (day70 post-infection) (Fig. 2A) or actA−LmOva (day 46 post-infection) (Fig. 2B). The gene discussed is CD4; the disease is infection.