Spleens were harvested from mice and single cell suspensions were generated [65] . Cells were counted and diluted in RPMI-1640 media (Sigma, Saint Louis, MO) supplemented with 10% fetal calf serum (HyClone, Logan, UT), 100 U penicillin/ml, 100 mg/ml streptomycin, 10 mM HEPES (N-2-hydroxyethylpiperazine-N9-2-ethanesulfonic acid), 1mM sodium pyruvate, 50 mM 2-mercaptoethanol and 2 mM L-glutamine (cRPMI). In all adoptive transfer experiments, 1610 7 cells were injected into persistently infected RAG1-/-mice by intraperitoneal (i.p.) injection in 0.5ml cRPMI.