Figure 2. The FTA assay can measure magnitude, functional avidity and epitope variant cross-reactivity of CTL responses in vivo.

Six BALB/c mice were vaccinated with 5×10⁶ PFU VV Western Reserve i.p. A FTA was constructed using mouse splenocytes and comprised of fluorescent target cells pulsed with 6 different concentrations of the MHC-I binding peptides F2L, F2L mut, A52R, and HIV neg (as a negative control). FTA target cells were injected i.v. into infected mice 6 days post vaccination and after 18 hr in vivo % specific killing calculated for FTA target cells from harvested spleens. a) In vivo killing responses from six infected animals. b) Summary of responses from all mice with means of % specific killing and standard error of mean. c) Mean area under curve (AUC) measurements from % specific killing response curves and associated standard error of means. d) Mean effective concentration of peptides used to pulse target cells that generated half maximal responses (EC₅₀) and associated standard error of means and P values.