Figure 3. Influence of vector on IFN-γ ELISPOT responses to a rBCG-RT or rBCGpan-RT prime and rMVA boost.

Groups of mice were primed with the indicated rBCG vaccines (10⁷ cfu or 10⁵ cfu) then boosted with rMVA (10⁴ pfu) on day 28. One group of mice was left unvaccinated then vaccinated on day 28 with rMVA. On day 40 spleens were harvested and splenocytes pooled from 5 mice per group. (A) IFN-γ ELISPOT assays with RT CD8⁺ T cell and CD4⁺ T cell peptides or peptide H CD8⁺ T cell peptide. Bars are the average and standard deviation of the average IFN-γ ELISPOT responses for the indicated individual peptides for 3 separate experiments. Asterisks indicate statistical significance of the mean IFN-γ ELISPOT responses for the individual peptides for a rBCG-RT or rBCGpan-RT vaccine prime and rMVA boost compared to that for the respective BCG- Control or rBCGpan-Control vaccine prime and rMVA boost. (B) Splenocytes were stained with H-2K^d and H-2D^d MHC class I pentamers folded with the RT CD8⁺ T cell peptide or peptide H CD8⁺ T cell peptide and flow cytometry was used to determine the frequency of RT- and peptide H-specific CD8⁺ T cells in the splenocyte population. Bars are the average of triplicate values for RT- and peptide H-specific CD8⁺ T cells expressed as a percentage of the total gated CD8⁺ T cell population for a single experiment. The coefficient of variation of all average values (standard deviation of the average expressed as a percentage of the average) was less than 0.01%. Asterisks indicate the statistical significance of the mean values for the percentage of CD8⁺ RT- or peptide H-specific T cells for a rBCG-RT or rBCGpan-RT vaccine prime and rMVA boost compared to that for the respective rBCG-Control or rBCGpan-Control vaccine prime and rMVA boost. Respective differences for peptide responses between groups are also indicated. *<0.01; **<0.05; Student's t-test for means of unpaired data.