Quantitation of INF-c positive CD8+ T cells isolated from splenocytes or mononuclear cells from bronchioalveolar lavage (BAL), mesenteric lymph nodes (MLN) and Peyer's patches (PP) 45 days after vaccination was performed using an ELISPOT assay (ELISPOT Mouse Set, BD PharMingen, San Diego, CA) according to the manufacturer's instructions. Briefly, a 96-well ELISPOT plate was coated with 5 mg/ml anti-mouse IFN-c capture antibody. Cells pooled from 4 B10.BR mice per experimental group were added to microwells along with the TELRTFSI peptide (2 mg/well). Control cells were incubated either without peptide or with the non-specific stimulator, SEB (200 ng/ml). After incubation with a biotinylated anti-mouse IFNc detection antibody and Streptavidin-horseradish peroxidase antibody, wells were counted using an ELISPOT reader (AID EliSpot reader system, Cell Technology, Colombia, MD).