Figure 1. EP DNA vaccination induces high sensitivity Gag293 specific responses.
(A, B, C) IFNγ ELISpot responses in ADVAX vaccine recipients: production of IFNγ by CD4+ T cell lines specific for Gag293 (A), Gag263 (B), and Gag161 (C) were compared between healthy volunteers who received the ADVAX vaccine via electroporation (EP; circles), by intramuscular injection (IM; squares; n=6), or who received a saline solution by electroporation (Placebo; triangles; week 10, n=4; week 38, n=2). In the EP group, samples obtained at week 10 (solid symbol, n=7) or week 38 (open symbol, n=5) are distinguished. IFNγ production was measured by ELISpot assay on CD4+ T cell lines restimulated with 10−5 M peptide, and was expressed by the number of spot forming cells (SFC) per million cells. Statistically significant differences (P < 0.05) computed using the Mann Whitney U test are reported.
(D) Representative example of antigen sensitivity measurement in a Gag293-specific cell line from a volunteer in the ADVAX EP group (1 out of 24 experiments is shown). The IFNγ ELISpot response was measured in function of decreasing doses of Gag293 peptide, and antigen sensitivity was determined as the last positive dilution of peptide which elicited a positive IFNγ response 2-fold over background. Arrow indicates the last positive dilution in this example (0.5μM).
(E) Comparison of antigen sensitivity in Gag293-specific CD4+ T cell lines derived from HIV Controllers (HIC, hexagonal symbols, n=15), treated patients (HAART, diamonds, n=17), and vaccinees (ADVAX EP, circles) analyzed at week 10 (solid symbols, n=4) and week 38 (open symbols n=4). ADVAX samples with undetectable Gag293 responses are not shown. Significant differences (P < 0.05) obtained by the Mann-Whitney U test are reported.
(F) Comparison of the antigen sensitivity of Gag293-specific CD4+ T cell lines from ADVAX EP samples (n=4) obtained at week 10 (solid circle), two weeks after 2nd EP vaccination, or at week 38 (open circle), two weeks after the third EP vaccination. The data point with an undetectable IFN-γ ELISpot response has been arbitrarily assigned an antigen sensitivity of 10−5 M (star symbol), corresponding to the limit of detection of the assay.