For flow cytometry analysis, approximately 1610 6 splenocytes, isolated from infected mice (Lm, L.inn, and L.inn::vgc strains) were stained with FITC labelled anti-CD8 and biotinylated anti-CD62L or anti-CD44 (pharMingen, Becton Dickinson). PEconjugated streptavidin was used to detect the binding of anti-CD62L or anti-CD44 on the cell surface. Flow cytometry was performed using a FACS Calibur flow cytometer and further analyzed with CELL Quest software (Becton Dickinson, CA).