Fig. 4.

Immune response to vaccination and challenge: The frequency of PPD-specific IFN-γ secreting cells measured after BCG vaccination and challenge measured by ELISpot. Panel A: response profile in Group A which received BCG as a single intradermal injection; Panel B: response profile in Group B which received BCG in a BCG ID prime/IT boost regimen; Panel C: response profile in Group C which received BCG as a single intravenous injection and Panel D shows the response in Group D which did not receive BCG vaccination. Vaccination with BCG at week 0 is indicated by the dashed line, intra-tracheal vaccination with BCG indicated by the dotted line at week 12 and aerosol exposure to M. tuberculosis indicated by the long dashed line at week 21.