Determination of the optimal dosage of MVA-Gag^M to boost a BCG-Gag^M prime.

(A) Mice were primed on day 0 with 2 x 10⁷ cfu BCG-Gag^M (Group 1–3) or BCG^E (Group 4–6) and boosted on day 70 with 10² (Group 1 and 4), 10⁴ (Group 2 and 5), or 10⁶ (Group 3 and 6) pfu MVA-Gag^M. (B) Cumulative IFN-γ ELISPOT CD8⁺ and CD4⁺ responses of vaccinated mice to HIV-1 Gag peptides. The ELISPOT assay was carried out using three Gag-specific peptides for stimulation of pooled splenocytes that were isolated 12 days post the MVA-Gag^M boost. Bars represent the magnitude of net responses to individual peptides, expressed as sfu/10⁶ splenocytes after subtracting the background. (C) and (D) Total frequency of T cells producing IFN-γ, IL-2, and/or TNF-α, after subtracting the background, in response to HIV-1 Gag peptide stimulation following a rBCG prime and an MVA-Gag^M boost at different doses. Cells were positive for cytokine production if the proportion was ≥0.05% after subtracting the background. These results are from a single experiment using pooled splenocytes.